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Surgery_Schwartz. for the AVM usually is delayed 3 to 4 weeks to allow the brain to recover from acute injury. There is less risk of devastating early rebleeding from AVMs, and vasospasm is much less common. Three therapeutic modalities for AVMs are currently in common use: microsurgical exci-sion, interventional radiology or endovascular embolization, and stereotactic radiosurgery (SRS). AVMs that are large, near eloquent cortex, or that drain to deep venous structures are con-sidered high grade and more difficult to surgically resect with-out causing a significant neurologic deficit. Radiosurgery can treat these lesions, although it is limited to lesions <3 cm in diameter and has a 2-year lag time (i.e., the AVM may bleed in the interval). Embolization reduces flow through the AVM. It is usually considered adjunctive therapy, but it may serve as the sole treatment for deep, inaccessible lesions.4Brunicardi_Ch42_p1827-p1878.indd 185301/03/19 7:16 PM 1854SPECIFIC CONSIDERATIONSPART IITUMORS OF THE


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Surgery_Schwartz. adjunctive therapy, but it may serve as the sole treatment for deep, inaccessible lesions.4Brunicardi_Ch42_p1827-p1878.indd 185301/03/19 7:16 PM 1854SPECIFIC CONSIDERATIONSPART IITUMORS OF THE CENTRAL NERVOUS SYSTEMA wide variety of tumors affect the brain and spine. Primary benign and malignant tumors arise from the various elements of the CNS, including neurons, glia, and meninges. Tumors metas-tasize to the CNS from many primary sources. Presenta-tion varies widely depending on relevant neuroanatomy. Prognosis depends on histology and anatomy. Modern brain tumor centers use team approaches to CNS tumors, as patients may require a combination of surgery (including newer, more minimally invasive approaches), radiation therapy, chemother-apy, SRS, and research protocol enrollment for studies assessing the efficacy of newer approaches such as immunotherapy. Tumors affecting the peripheral nervous system are discussed in the “Peripheral Nerve” section.Intracranial TumorsIntracranial


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Surgery_Schwartz. assessing the efficacy of newer approaches such as immunotherapy. Tumors affecting the peripheral nervous system are discussed in the “Peripheral Nerve” section.Intracranial TumorsIntracranial tumors can cause brain injury from mass effect, dys-function or destruction of adjacent neural structures, swelling, or abnormal electrical activity (seizures). Supratentorial tumors commonly present with focal neurologic deficit, such as contra-lateral limb weakness, visual field deficit, headache, or seizure. Infratentorial tumors often cause increased ICP due to hydro-cephalus from compression of the fourth ventricle, leading to headache, nausea, vomiting, or diplopia. Cerebellar hemisphere or brain stem dysfunction can result in ataxia, nystagmus, or cranial nerve palsies. Infratentorial tumors rarely cause seizures.All patients with symptoms concerning for brain tumor should undergo MRI with and without gadolinium. Gadolinium-based contrast can identify locations of blood-brain barrier


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Surgery_Schwartz. rarely cause seizures.All patients with symptoms concerning for brain tumor should undergo MRI with and without gadolinium. Gadolinium-based contrast can identify locations of blood-brain barrier break-down of tumors and, when used in conjunction with other MRI sequences, is essential in narrowing the differential diagnosis. Ini-tial management of a patient with a symptomatic brain tumor gen-erally includes dexamethasone for reduction of vasogenic edema, and phenytoin or levetiracetam if the patient has seized. Patients with significant weakness, lethargy, or hydrocephalus should be admitted for observation until definitive care is administered.Metastatic TumorsCerebral metastases are the most common type of intracranial tumor. Prolonged cancer patient survival and improved CNS imaging have increased the likelihood of diagnosing cerebral metastases. The sources of most cerebral metastases are (in decreasing frequency): lung, breast, kidney, GI tract, and mela-noma. Lung and breast


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Surgery_Schwartz. have increased the likelihood of diagnosing cerebral metastases. The sources of most cerebral metastases are (in decreasing frequency): lung, breast, kidney, GI tract, and mela-noma. Lung and breast cancers account for more than half of cerebral metastases. Metastatic cells usually travel to the brain hematogenously and frequently seed the gray-white junction due to characteristic blood vessel caliber change. Other com-mon locations are the cerebellum and the meninges. Menin-geal involvement may result in carcinomatous meningitis, also known as leptomeningeal carcinomatosis. MRI preand post-contrast administration is the study of choice for evaluation. Figure 42-20 demonstrates bilateral cerebellar metastases. These lesions are typically well circumscribed, round, and multiple. Such findings should prompt a metastatic work-up, including CT scan of the chest, abdomen, and pelvis, and a bone scan.Management largely depends upon the primary tumor, overall tumor burden, patient’s medical


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Surgery_Schwartz. should prompt a metastatic work-up, including CT scan of the chest, abdomen, and pelvis, and a bone scan.Management largely depends upon the primary tumor, overall tumor burden, patient’s medical condition, and location and number of metastases. The beliefs of the patient and family regarding aggressive care must be considered, with the primary goal of optimizing survival time while maintaining or improv-ing neurological function. Neurosurgical intervention can be indicated for a number of reasons. Biopsy can be obtained to provide a tissue diagnosis and further direct therapy. Hydro-cephalus from increased intracranial pressure due to intracranial tumor burden can be temporized via placement of a ventricu-loperitoneal shunt. Craniotomy can be used for debulking of intracranial tumor burden or resection. Data from random-ized controlled trials have supported the use of craniotomy for tumor resection plus whole-brain radiation therapy (WBRT) or stereotactic radiosurgery (SRS) for


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Surgery_Schwartz. burden or resection. Data from random-ized controlled trials have supported the use of craniotomy for tumor resection plus whole-brain radiation therapy (WBRT) or stereotactic radiosurgery (SRS) for patients with a single surgically accessible metastatic lesion, compared to radiation therapy alone. In one randomized trial assessing surgery and WBRT vs. WBRT alone, local recurrence decreased and median 5ABFigure 42-19. A. Lateral view after injection of contrast dye in the left internal carotid artery demonstrates a 3 × 4 cm left frontal arteriove-nous malformation indicated by arrowheads. This image was taken 1.06 seconds after dye injection, and is referred to as an arterial phase image. B. Same view taken 4.10 seconds after dye injection, providing a venous phase image. The arrow points to the arteriovenous malfor-mation nidus. The arrowheads indicate two pathologically enlarged draining veins. ACA = anterior cerebral artery; ICA = internal carotid artery; MCA = middle cerebral


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Surgery_Schwartz. to the arteriovenous malfor-mation nidus. The arrowheads indicate two pathologically enlarged draining veins. ACA = anterior cerebral artery; ICA = internal carotid artery; MCA = middle cerebral artery.Brunicardi_Ch42_p1827-p1878.indd 185401/03/19 7:16 PM 1855NEUROSURGERYCHAPTER 42survival increased from 15 to 40 weeks.67 For multiple metas-tases, it should be noted that craniotomy primarily for resec-tion is typically not indicated unless all detectable metastases can be resected. It may however still be useful for symptomatic relief from a primary lesion. Recent data suggest that SRS (e.g. Gamma Knife) may be applied to multiple metastases in one session with improved outcome.68Glial TumorsGlial cells provide the anatomic and physiologic support for neurons and their processes in the brain. Tumors arising from glial cells are termed gliomas, and they represent the most com-mon primary brain tumor. The several types of glial cells give rise to distinct primary CNS


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Surgery_Schwartz. processes in the brain. Tumors arising from glial cells are termed gliomas, and they represent the most com-mon primary brain tumor. The several types of glial cells give rise to distinct primary CNS neoplasms.Astrocytoma. Astrocytoma is the most common primary CNS neoplasm. The term glioma often is used to refer to astrocyto-mas specifically, excluding other glial tumors. Astrocytomas are graded from I to IV. Grades I and II are referred to as low-grade astrocytoma or low grade glioma, grade III as anaplastic astro-cytoma, and grade IV as glioblastoma multiforme (GBM). Prog-nosis varies significantly between grades I/II, III, and IV, but not between I and II. Median survival is 8 years after diagnosis with a low-grade tumor, 2 to 3 years with an anaplastic astrocytoma, and roughly 1 year with a GBM. GBMs account for almost two-thirds of all astrocytomas, anaplastic astrocytomas account for two-thirds of the rest, and low-grade astrocytomas the remainder. Fig. 42-21 demonstrates the


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Surgery_Schwartz. with a GBM. GBMs account for almost two-thirds of all astrocytomas, anaplastic astrocytomas account for two-thirds of the rest, and low-grade astrocytomas the remainder. Fig. 42-21 demonstrates the typical appearance of a GBM.The great majority of astrocytomas infiltrate adjacent brain. Juvenile pilocytic astrocytomas and pleomorphic xantho-astrocytomas are exceptions. These tumors are circumscribed, low grade, and associated with a good prognosis. Histologic features associated with higher grade include hypercellularity, nuclear atypia, and endovascular hyperplasia. Necrosis is pres-ent only with GBMs; it is required for the diagnosis.Gross total resection should be attempted for suspected astrocytomas. Motor cortex, language centers, deep or midline structures, or brainstem location may make this impossible without unacceptable, devastating neurologic deficit. Advanced imaging, such as diffusion tensor imaging (DTI) and functional MRI (fMRI), are seeing increased use as means of


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Surgery_Schwartz. may make this impossible without unacceptable, devastating neurologic deficit. Advanced imaging, such as diffusion tensor imaging (DTI) and functional MRI (fMRI), are seeing increased use as means of assessing peritumoral structure and function to guide surgical decision-making. However, some lesions may be in such precarious regions as to be limited to stereotactic needle biopsy specimen. Gross total resection followed by fractioned radiotherapy (FRT) improves survival for all grades, although radiation therapy may be delayed until recurrence in low-grade tumors. Alongside FRT, adjuvant chemotherapy with temozolomide was demon-strated in a randomized controlled trial to increase short-term survival rate.69 Bevacizumab, an anti-VEGF antibody, is another treatment option under investigation. There are various ongoing research studies for GBM adjuvant therapy; these should be dis-cussed with the patient and family. Other options include Iotrex-containing balloons for conformal radiation


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Surgery_Schwartz. There are various ongoing research studies for GBM adjuvant therapy; these should be dis-cussed with the patient and family. Other options include Iotrex-containing balloons for conformal radiation brachytherapy (Glia-Site), placed in the resection cavity at the time of surgery ABFigure 42-20. A. Precontrast T1-weighted axial magnetic resonance imaging demonstrating bilateral hemorrhagic cerebellar metastases. Patient presented with ataxia and then lethargy progressing to deep coma. This patient has total effacement of the fourth ventricle and severe brain stem compression. The fourth ventricle cerebrospinal fluid space should be at the tip of the arrowhead. Patient recovered to normal mental status after emergent posterior fossa craniotomy. B. Postcontrast T1-weighted axial magnetic resonance imaging demonstrating a ring-enhancing lesion in the lateral left temporal lobe with moderate edema. The uncus (U) is compressing the left cerebral peduncle (CP) and displacing the brain stem to


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Surgery_Schwartz. imaging demonstrating a ring-enhancing lesion in the lateral left temporal lobe with moderate edema. The uncus (U) is compressing the left cerebral peduncle (CP) and displacing the brain stem to the right.Brunicardi_Ch42_p1827-p1878.indd 185501/03/19 7:17 PM 1856SPECIFIC CONSIDERATIONSPART IIfor recurrence. Adjuvant therapy remains marginally effective; survival has changed little over the last several decades.Oligodendroglioma. Oligodendroglioma accounts for approx-imately 10% of gliomas, arising from the oligodendrocytes that create myelin in the CNS. They often present with seizures. Calcifications and hemorrhage on CT or MRI suggest the diag-nosis. Oligodendrogliomas are also graded from I to IV; grade portends prognosis. Prognosis is better overall than for astro-cytomas. Median survival ranges from 2 to 7 years for high-est and lowest grade tumors, respectively. Aggressive resection improves survival. Many oligodendrogliomas will respond to procarbazine, lomustine (CCNU),


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Surgery_Schwartz. survival ranges from 2 to 7 years for high-est and lowest grade tumors, respectively. Aggressive resection improves survival. Many oligodendrogliomas will respond to procarbazine, lomustine (CCNU), and vincristine (PCV) che-motherapy. A particular chromosomal deletion, 1p19q, has been associated with robust response to the chemotherapeutic agent temozolomide. Radiation has not been clearly shown to prolong survival.Recent updates to brain tumor classification by the WHO (discussed in the following section) note that high-grade (at least II or III) oligodendrogliomas and astrocytomas are classi-fied together as diffuse gliomas. In fact, more similarity is seen between high-grade astrocytomas and oligodendrolgiomas than between high-grade astrocytomas and low-grade astrocytomas. Further discussion of this nosology is beyond the scope of this chapter, but implications for the future of neuro-oncology are discussed here.Ependymoma. The lining of the ventricular system consists of


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Surgery_Schwartz. discussion of this nosology is beyond the scope of this chapter, but implications for the future of neuro-oncology are discussed here.Ependymoma. The lining of the ventricular system consists of cuboidal/columnar ependymal cells from which ependy-momas may arise. Although most pediatric ependymomas are supratentorial, two-thirds of adult ependymomas are infratento-rial. Supratentorial ependymomas arise from the lateral or third ventricles. The infratentorial tumors arise from the floor of the fourth ventricle (i.e., off the posterior brainstem). The most com-mon symptoms are headache, nausea, vomiting, or vertigo, sec-ondary to increased ICP from obstruction of CSF flow through the fourth ventricle. The tumors may grow out the foramina of Luschka to form a cerebellopontine angle mass. They may also spread through the CSF to form “drop mets” in the spinal canal. The two main histologic subtypes are papillary and anaplastic, the latter characterized by increased mitotic activity and


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Surgery_Schwartz. They may also spread through the CSF to form “drop mets” in the spinal canal. The two main histologic subtypes are papillary and anaplastic, the latter characterized by increased mitotic activity and areas of necrosis. Gross total resection often is impossible because the tumor arises from the brain stem. The goal of surgery is to achieve maximal resection without injuring the very delicate brainstem. Suboccipital craniotomy and midline separation of the cerebellar hemispheres allows access to tumors in the fourth ventricle. Postoperative radiation therapy significantly improves survival. Patients with CSF spread documented by LP or con-trast MRI should also have whole-spine radiation plus focused doses to visualized metastases.Choroid Plexus Papilloma. The choroid plexus is composed of many small vascular tufts covered with cuboidal epithelium. It represents part of the interface between blood and brain. The choroid cells create CSF from blood via ultrafiltration and release it into


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Surgery_Schwartz. small vascular tufts covered with cuboidal epithelium. It represents part of the interface between blood and brain. The choroid cells create CSF from blood via ultrafiltration and release it into the ventricular system. Choroid plexus papil-lomas and choroid plexus carcinomas (rare, mostly pediatric) may arise from these cells. Papillomas usually occur in infants (typically supratentorial in the lateral ventricle) but also occur in adults (usually infratentorial in the fourth ventricle). Papillomas ABFigure 42-21. A. Postcontrast T1-weighted axial magnetic resonance imaging demonstrating a ring-enhancing lesion in the anteromedial right temporal lobe with central necrosis (dark area) consistent with glioblastoma multiforme. B. T2-weighted axial magnetic resonance imaging with extensive bright signal signifying peritumoral edema seen with glioblastoma multiformes.Brunicardi_Ch42_p1827-p1878.indd 185601/03/19 7:17 PM 1857NEUROSURGERYCHAPTER 42are well circumscribed and vividly


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Surgery_Schwartz. bright signal signifying peritumoral edema seen with glioblastoma multiformes.Brunicardi_Ch42_p1827-p1878.indd 185601/03/19 7:17 PM 1857NEUROSURGERYCHAPTER 42are well circumscribed and vividly enhance due to extensive vasculature. Like ependymomas, adult choroid plexus papillo-mas usually present with symptoms of increased ICP. Treatment is surgical excision. Total surgical excision is curative; recurrent papillomas should be re-resected. Radiation and chemotherapy are not indicated for papillomas. Radiation is adjunctive to aggressive surgery for carcinomas, but the results are generally poor.Neural Tumors and Mixed TumorsNeural and mixed tumors are a diverse group that includes tumors variously containing normal or abnormal neurons and/or normal or abnormal glial cells. Primitive neuroectodermal tumors arise from bipotential cells, capable of differentiating into neurons or glial cells.Medulloblastoma. Medulloblastoma is classically described as the most common type of primitive


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Surgery_Schwartz. tumors arise from bipotential cells, capable of differentiating into neurons or glial cells.Medulloblastoma. Medulloblastoma is classically described as the most common type of primitive neuroectodermal tumor (PNET), although this term has been removed in the latest WHO classification of central nervous system tumors. Most occur in the first decade of life, but there is a second peak around age 30. Medulloblastoma is the most common malignant pediatric brain tumor. They are usually midline. Most occur in the cerebellum and present with symptoms of increased ICP. Histologic char-acteristics include densely packed small round cells with large nuclei and scant cytoplasm. They are generally not encapsulated, frequently disseminate within the CNS, and should undergo sur-gical resection followed by radiation therapy and chemotherapy.Ganglioglioma. Ganglioglioma is a mixed tumor in which both neurons and glial cells are neoplastic. They occur in the first three decades of life, often in the


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Surgery_Schwartz. by radiation therapy and chemotherapy.Ganglioglioma. Ganglioglioma is a mixed tumor in which both neurons and glial cells are neoplastic. They occur in the first three decades of life, often in the medial temporal lobe, as circumscribed masses that may contain cysts or calcium and may enhance. The presenting symptom is usually a seizure, due to the medial temporal location. Patients have a good prognosis after complete surgical resection.Neural Crest TumorsMultipotent neural crest cells develop into a variety of dispa-rate cell types, including smooth muscle cells, sympathetic and parasympathetic neurons, melanocytes, Schwann cells, and arachnoid cap cells. They migrate in early development from the primitive neural tube throughout the body.Miscellaneous TumorsMeningioma. Meningiomas are derived from arachnoid cap cells of the arachnoid mater. They appear to arise from the dura mater grossly and on MRI and are commonly referred to as dural-based tumors. The most common intracranial


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Surgery_Schwartz. derived from arachnoid cap cells of the arachnoid mater. They appear to arise from the dura mater grossly and on MRI and are commonly referred to as dural-based tumors. The most common intracranial locations are along the falx (Fig. 42-22), the convexities (i.e., over the cerebral hemispheres), and the sphenoid wing. Less common locations include the foramen magnum, olfactory groove, and inside the lateral ventricle. Most are slow growing, encapsu-lated, benign tumors. Aggressive atypical or malignant menin-giomas may invade adjacent bone or cerebral cortex. Previous cranial irradiation increases the incidence of meningiomas. Approximately 10% of patients with a meningioma have multiple meningiomas. Total resection is curative, although involvement with small perforating arteries or cranial nerves may make total resection of skull base tumors impossible with-out significant neurologic deficit. The Simpson grading scale is used to characterize the extent of resection. Small,


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Surgery_Schwartz. or cranial nerves may make total resection of skull base tumors impossible with-out significant neurologic deficit. The Simpson grading scale is used to characterize the extent of resection. Small, asymptom-atic meningiomas can be followed until symptomatic or until significant growth is documented on serial imaging studies. Atypical and malignant meningiomas may require postoperative radiation. Patients may develop recurrences from the surgical bed or distant de novo tumors.Vestibular Schwannoma (Acoustic Neuroma). Vestibular schwannomas predominantly arise from the superior half of the vestibular portion of the vestibulocochlear nerve (cranial nerve VIII) (Fig. 42-23). Commonly, patients present with progressive hearing loss, tinnitus, or balance difficulty. Large tumors may cause brain stem compression and obstructive hydrocephalus. Bilateral acoustic neuromas are pathognomonic for neurofibro-matosis type 2 (NF2), a syndrome resulting from mutation of chromosome 22. NF2 patients


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Surgery_Schwartz. stem compression and obstructive hydrocephalus. Bilateral acoustic neuromas are pathognomonic for neurofibro-matosis type 2 (NF2), a syndrome resulting from mutation of chromosome 22. NF2 patients have an increased incidence of spinal and cranial meningiomas and gliomas.Vestibular schwannomas may be treated with microsur-gical resection or SRS (Gamma Knife radiosurgery or linear accelerator technology). The main complication with treatment is damage to the facial nerve (cranial nerve VII), which runs through the internal auditory canal with the vestibulocochlear nerve. Risk of facial nerve dysfunction increases with increasing tumor diameter. SRS is preferred for tumors <3 cm, and micro-surgical resection for those >3 cm (SRS can be supplemented for any residual tumor following resection).Pituitary Adenoma. Pituitary adenomas arise from the anterior pituitary gland (adenohypophysis). Tumors <1 cm diameter are considered microadenomas; larger tumors are macroadenomas. Figure


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Surgery_Schwartz. resection).Pituitary Adenoma. Pituitary adenomas arise from the anterior pituitary gland (adenohypophysis). Tumors <1 cm diameter are considered microadenomas; larger tumors are macroadenomas. Figure 42-22. Postcontrast T1-weighted coronal magnetic reso-nance imaging demonstrating a brightly enhancing lesion arising from the falx cerebri with moderate edema and mass effect on the right lateral ventricle. This is a falcine meningioma. Note also the small separate meningioma arising from the dura over the cerebral convexity.Brunicardi_Ch42_p1827-p1878.indd 185701/03/19 7:17 PM 1858SPECIFIC CONSIDERATIONSPART IIPituitary tumors may be functional (i.e., secrete endocrinologi-cally active compounds at pathologic levels) or nonfunctional (i.e., secrete nothing or inactive compounds). Functional tumors are often diagnosed when quite small, due to endocrine dysfunc-tion. The most common endocrine syndromes are Cushing’s disease, due to adrenocorticotropic hormone secretion, ForbesAlbright


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Surgery_Schwartz. tumors are often diagnosed when quite small, due to endocrine dysfunc-tion. The most common endocrine syndromes are Cushing’s disease, due to adrenocorticotropic hormone secretion, ForbesAlbright syndrome, due to prolactin secretion, and acromegaly, due to growth hormone secretion. Nonfunctional tumors are typically diagnosed as larger lesions causing mass effects such as visual field deficits due to compression of the optic chiasm or panhypopituita-rism due to compression of the gland. Figure 42-24 demonstrates a large pituitary adenoma. Hemorrhage into a pituitary tumor causes abrupt symptoms of headache, visual disturbance, decreased men-tal status, and endocrine dysfunction. This is known as pituitary apoplexy.Symptomatic pituitary tumors should be decompressed surgically to eliminate mass effect and/or to attempt an endo-crine cure. However, prolactin-secreting tumors (prolactinomas) usually shrink with dopaminergic therapy alone. First-line phar-macotherapy for small


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Surgery_Schwartz. eliminate mass effect and/or to attempt an endo-crine cure. However, prolactin-secreting tumors (prolactinomas) usually shrink with dopaminergic therapy alone. First-line phar-macotherapy for small prolactinomas is cabergoline, a dopamine agonist that inhibits production and secretion of prolactin, and is preferred over bromocriptine for its superior side effect profile. Consider surgery for prolactinomas with persistent mass effect or endocrinologic dysfunction in spite of adequate dopamine agonist therapy. Most pituitary tumors are approached transna-sally via the transsphenoidal approach, and minimally invasive, endoscopic surgical techniques are being used increasingly.Hemangioblastoma. Hemangioblastomas occur almost exclusively in the posterior fossa, with about 20% occurring in patients with von Hippel-Lindau (VHL) disease, a multisys-tem neoplastic disorder. Other tumors associated with VHL are renal cell carcinoma, pheochromocytoma, and retinal angio-mas. Many appear as cystic


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Surgery_Schwartz. with von Hippel-Lindau (VHL) disease, a multisys-tem neoplastic disorder. Other tumors associated with VHL are renal cell carcinoma, pheochromocytoma, and retinal angio-mas. Many appear as cystic tumors with an enhancing tumor on the cyst wall known as the mural nodule. Surgical resection is curative for sporadic (non-VHL associated) tumors. Pathology reveals abundant thin-walled vascular channels; internal debulk-ing may be bloody. En bloc resection of the mural nodule alone, leaving the cyst wall, is sufficient.Lymphoma. CNS lymphoma may arise either primarily in the CNS or secondarily from systemic disease. Recent rising inci-dence may be due to growing transplant and AIDS populations. Presenting symptoms include mental status changes, headache due to increased ICP, and cranial nerve palsy due to lymphoma-tous meningitis (analogous to carcinomatous meningitis). Often, lymphoma appears hyperdense on CT due to dense cellularity. Most lesions typically enhance with contrast on MRI,


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Surgery_Schwartz. palsy due to lymphoma-tous meningitis (analogous to carcinomatous meningitis). Often, lymphoma appears hyperdense on CT due to dense cellularity. Most lesions typically enhance with contrast on MRI, and can be differentiated by diffusion restriction on diffusion-weighted sequences. Surgical excision is not indicated. A stereotactic needle biopsy specimen usually confirms the diagnosis. Sub-sequent treatment includes steroids, whole-brain radiation, and chemotherapy. Intrathecal methotrexate is an additional treat-ment option.Embryologic TumorsEmbryologic tumors result from embryonal remnants that fail to involute completely or differentiate properly during development.Craniopharyngioma. Craniopharyngiomas are benign cystic lesions that occur in the sellar region that occur most frequently in children. A second peak of incidence also exists around 50 years of age. Craniopharyngiomas arise from remnant embry-onic tissue in the pituitary stalk. Calcification occurs in all pedi-atric and


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Surgery_Schwartz. in children. A second peak of incidence also exists around 50 years of age. Craniopharyngiomas arise from remnant embry-onic tissue in the pituitary stalk. Calcification occurs in all pedi-atric and roughly half of adult craniopharyngiomas. Symptoms result from compression of adjacent structures, especially the optic chiasm. Pituitary or hypothalamic dysfunction or hydro-cephalus may develop. Treatment is primarily surgical. Excision ABFigure 42-23. A. Postcontrast T1-weighted axial magnetic resonance imaging demonstrating a brightly enhancing mass on the right ves-tibular nerve with an enhancing tail going into the internal auditory canal (arrowhead). Pathology demonstrated vestibular schwannoma. B. Postcontrast T1-weighted sagittal magnetic resonance imaging of the same lesion, indicated by the arrowhead. Note small incidental meningioma at the top of the scan.Brunicardi_Ch42_p1827-p1878.indd 185801/03/19 7:17 PM 1859NEUROSURGERYCHAPTER 42is somewhat easier in children, as the


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Surgery_Schwartz. by the arrowhead. Note small incidental meningioma at the top of the scan.Brunicardi_Ch42_p1827-p1878.indd 185801/03/19 7:17 PM 1859NEUROSURGERYCHAPTER 42is somewhat easier in children, as the tumor is often soft and easily suctioned. Adult tumors are often firm and adherent to adjacent vital structures. Visual loss, pituitary endocrine hypo-function, diabetes insipidus, and cognitive impairment from basal frontal injury are common complications.Epidermoid. Epidermoid tumors are cystic lesions with strati-fied squamous epithelial walls from trapped ectodermal cell rests that grow slowly and linearly by desquamation into the cyst cavity. The cysts contain keratin, cholesterol, and cellu-lar debris (Fig. 42-25). They occur most frequently in the cer-ebellopontine angle and may cause symptoms due to brainstem compression. Recurrent bouts of aseptic meningitis may occur due to release of irritative cyst contents into the subarachnoid space (Mollaret’s meningitis). Treatment is


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Surgery_Schwartz. symptoms due to brainstem compression. Recurrent bouts of aseptic meningitis may occur due to release of irritative cyst contents into the subarachnoid space (Mollaret’s meningitis). Treatment is surgical drainage and removal of the cyst wall. Intraoperative spillage of cyst contents may lead to severe chemical meningitis and must be avoided by containment and aspiration.Dermoid. Dermoids are less common than epidermoid tumors. They contain hair follicles and sebaceous glands in addition to a squamous epithelium. Dermoids may be found anywhere along the craniospinal axis. They are more commonly midline structures and are associated with more anomalies than epidermoids. They may be associated with trauma, as from a lumbar puncture that drags skin structures into the spine. Bacterial meningitis may occur when dermoids are associated with a dermal sinus tract. Treatment of symptomatic lesions is surgical resection, again with care to control cyst contents.Teratoma. Teratomas are germ


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Surgery_Schwartz. may occur when dermoids are associated with a dermal sinus tract. Treatment of symptomatic lesions is surgical resection, again with care to control cyst contents.Teratoma. Teratomas are germ cell tumors that arise in the midline, often in the pineal region (the area behind the third ventricle, above the midbrain and cerebellum). They contain elements from all three embryonal layers: ectoderm, meso-derm, and endoderm. Teratomas may contain skin, cartilage, GI glands, and teeth. Teratomas with more primitive features are more malignant, while those with more differentiated tissues are more benign. Surgical excision may be attempted. However, the prognosis for malignant teratomas is very poor.Spinal TumorsApproximately 20% of CNS tumors occur in the spine, and a wide variety of spinal tumors exist. Unlike cranial tumors, the majority of spinal tumors are histologically benign. Under-standing two major spinal concepts—stability and neural com-pression—facilitates an understanding of the


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Surgery_Schwartz. exist. Unlike cranial tumors, the majority of spinal tumors are histologically benign. Under-standing two major spinal concepts—stability and neural com-pression—facilitates an understanding of the effects of spinal tumors. Destruction of bones or ligaments can cause spinal instability, leading to deformities such as compression, kyphosis, subluxation, all of which harbor the potential for subsequent neural compression. Tumor growth in the spinal canal or neu-ral foramina can cause direct compression of the spinal cord or nerve roots and cause pain and loss of function. Classically, the pain is worse at night. Anatomic categorization provides the most logical approach to these tumors. Certain tumors present in characteristic locations. An understanding of the anatomy leads to an understanding of the clinical presentation and possible therapeutic options.Extradural Tumors. Extradural tumors account for approxi-mately 55% of spinal tumors. This category includes tumors Figure


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Surgery_Schwartz. understanding of the clinical presentation and possible therapeutic options.Extradural Tumors. Extradural tumors account for approxi-mately 55% of spinal tumors. This category includes tumors Figure 42-24. Postcontrast T1-weighted sagittal magnetic reso-nance imaging demonstrating a large sellar/suprasellar lesion (arrowheads) involving the third ventricle superiorly and abut-ting the midbrain and pons posteriorly. The patient presented with progressive visual field and acuity loss. Pathology and lab work revealed a nonfunctioning pituitary adenoma.Figure 42-25. Postcontrast T1-weighted axial magnetic resonance imaging demonstrating a nonenhancing mass in the left cerebello-pontine angle with brain stem compression. White arrowhead indi-cates interface of tumor and brain stem. Black arrowhead indicates deformed fourth ventricle. Pathology revealed epidermoid tumor.Brunicardi_Ch42_p1827-p1878.indd 185901/03/19 7:17 PM 1860SPECIFIC CONSIDERATIONSPART IIarising within the bony


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Surgery_Schwartz. arrowhead indicates deformed fourth ventricle. Pathology revealed epidermoid tumor.Brunicardi_Ch42_p1827-p1878.indd 185901/03/19 7:17 PM 1860SPECIFIC CONSIDERATIONSPART IIarising within the bony vertebral structures and from within the epidural space. Destruction of the bone can lead to instability and fractures, causing pain and/or deformity. Epidural expan-sion can lead to spinal cord or nerve root compression with myelopathy, radiculopathy, or a combination thereof.Metastatic Tumors Metastatic tumors are the most common extradural tumors. Spinal metastases most commonly occur in the thoracic and lumbar vertebral bodies because the greatest volume of red bone marrow is found in these regions. The most common primary sources of spine metastasis are lymphoma, lung, breast, and prostate. Other sources include renal, colon, thyroid, sarcoma, and melanoma. Most spinal metastases create osteolytic lesions. Osteoblastic, sclerotic lesions suggest pros-tate cancer in men and breast


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Surgery_Schwartz. Other sources include renal, colon, thyroid, sarcoma, and melanoma. Most spinal metastases create osteolytic lesions. Osteoblastic, sclerotic lesions suggest pros-tate cancer in men and breast cancer in women.Patients with progressive neurologic dysfunction due to a metastatic lesion should undergo urgent surgery followed by radiation therapy.70 Patients with debilitating pain may undergo radiation therapy with close observation for neurologic deterio-ration. Preoperative neurologic function correlates with postop-erative function. Patients may lose function over hours. These patients should be given high-dose IV dexamethasone, taken immediately to MRI, and then to the OR or radiation therapy suite. Indications for surgery include failure of radiation ther-apy, spinal instability, recurrence after radiation therapy, and the need for diagnosis in cases of unknown primary tumors. Most cases with significant bone involvement require both decom-pression and fusion. Bony fusion usually


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Surgery_Schwartz. after radiation therapy, and the need for diagnosis in cases of unknown primary tumors. Most cases with significant bone involvement require both decom-pression and fusion. Bony fusion usually takes 2 to 3 months. Prognosis governs operative decisions. Surgery is unlikely to improve quality of life for patients with a life expectancy of 3 months or less, but it is likely to improve quality of life for patients with life expectancy of 6 months or more. Benefit for patients with 3to 6-months’ life expectancy is unclear and requires frank discussion with the patient and family. Patients who are unlikely to tolerate general anesthesia, are already completely paralyzed, or who have very radiosensitive tumors such as multiple myeloma and lymphoma, should not generally undergo surgery.Management Principles of Spinal Cord Compression in Metastatic Cancer of the Spine Spinal cord compression due to tumor burden is important to distinguish because it can, as with any other form of cord


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Surgery_Schwartz. Principles of Spinal Cord Compression in Metastatic Cancer of the Spine Spinal cord compression due to tumor burden is important to distinguish because it can, as with any other form of cord compression, cause paralysis and loss of bowel and bladder function. A randomized controlled trial demonstrated that patients with spinal cord compression from metastatic tumor have better outcomes with decompres-sive surgery and radiotherapy compared to radiotherapy alone.70 Patients with radiosensitive tumors, such as multiple myeloma and lymphoma, are excluded from this group. Another impor-tant tool in assessing these patients is the SINS (Spinal Instabil-ity Neoplastic Score). This scale grades the utility of operative intervention in metastatic cancer to the spine on the basis of pain, deformity, location, type of bone lesion, integrity of verte-bral body, and posterior element involvement.71Primary Tumors Hemangiomas are benign tumors found in 10% of people at autopsy. They occur in the


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Surgery_Schwartz. location, type of bone lesion, integrity of verte-bral body, and posterior element involvement.71Primary Tumors Hemangiomas are benign tumors found in 10% of people at autopsy. They occur in the vertebral bodies of the thoracolumbar spine and are frequently asymptomatic. They are often vascular and may hemorrhage, causing pain or neurologic deficit. Large hemangiomas can destabilize the spine and predispose to fracture. Osteoblastic lesions include osteoid osteoma and osteoblastoma. The latter tends to be larger and more destructive. Aneurysmal bone cysts are nonneoplastic, expansile, lytic lesions containing thin-walled blood cavities that usually occur in the lamina or spinous processes of the cer-vicothoracic spine. They may cause pain or sufficiently weaken the bone to cause a fracture. Cancers arising primarily in the bony spine include Ewing’s sarcoma, osteosarcoma, chondro-sarcoma, and plasmacytoma.Intradural Extramedullary Tumors Intradural extramed-ullary tumors constitute


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Surgery_Schwartz. Cancers arising primarily in the bony spine include Ewing’s sarcoma, osteosarcoma, chondro-sarcoma, and plasmacytoma.Intradural Extramedullary Tumors Intradural extramed-ullary tumors constitute approximately 40% of spinal tumors and arise from the meninges or nerve root elements. They may compress the spinal cord, causing myelopathy, or the nerve roots, causing radiculopathy. The most common intradural extramedullary tumors are typically benign, slow growing, and well circumscribed. Rare benign epidural masses include arach-noid cysts, dermoids, and epidermoids. Rare malignant epidural tumors include metastases and high-grade gliomas, or “drop” metastases from posterior fossa gliomas.Meningioma Meningiomas arise from the arachnoidea mater. They appear to be dural based and enhance on MRI. An enhanc-ing “dural tail” may be seen. They occur most commonly in the thoracic spine (Fig. 42-26) but also arise in the cervical and lumbar regions. Some spinal meningiomas grow into the Figure


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Surgery_Schwartz. An enhanc-ing “dural tail” may be seen. They occur most commonly in the thoracic spine (Fig. 42-26) but also arise in the cervical and lumbar regions. Some spinal meningiomas grow into the Figure 42-26. T2-weighted sagittal magnetic resonance imaging of the midthoracic spine demonstrating a well-encapsulated tumor arising from the dura posteriorly and compressing the spinal cord. Arrowhead points to dorsal location of the mass. The patient pre-sented with worsening gait and lower extremity spasticity. Pathol-ogy demonstrated meningioma.Brunicardi_Ch42_p1827-p1878.indd 186001/03/19 7:17 PM 1861NEUROSURGERYCHAPTER 42epidural space. Growth causes cord compression and progres-sive myelopathy with hyperreflexia, spasticity, and gait difficul-ties. Surgical excision is the treatment of choice. The surgeon often finds a clean margin between the tumor, dura, and spinal cord, allowing en bloc resection without damage to the cord.Schwannoma Schwannomas are derived from peripheral nerve


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Surgery_Schwartz. choice. The surgeon often finds a clean margin between the tumor, dura, and spinal cord, allowing en bloc resection without damage to the cord.Schwannoma Schwannomas are derived from peripheral nerve sheath Schwann cells. They are benign, encapsulated tumors that rarely undergo malignant degeneration. While two-thirds are entirely intradural, one-sixth are entirely extradural, and one-sixth have a classic “dumbbell” shape from intradural and extra-dural components. Symptoms result from radiculopathy, often presenting as pain or myelopathy. Symptomatic lesions should be surgically resected. The parent nerve root usually can be pre-served. Patients with multiple schwannomas likely have NF2. In these patients, a careful neurologic examination is needed to determine which lesions are symptomatic and require resection.Neurofibroma In contrast to schwannomas, neurofibromas tend to appear more fusiform and to grow within the parent nerve, rather than forming an encapsulated mass branching


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Surgery_Schwartz. and require resection.Neurofibroma In contrast to schwannomas, neurofibromas tend to appear more fusiform and to grow within the parent nerve, rather than forming an encapsulated mass branching off the nerve. Neurofibromas are benign but not encapsulated. They present similarly to schwannomas, and the two may be difficult to differentiate on imaging. Salvage of the parent nerve is more challenging with neurofibromas. To improve the likelihood of total resection, thoracic and high cervical nerve roots may be sacrificed with minimal deficit. Patients with multiple neurofi-bromas likely have NF1, also known as von Recklinghausen’s neurofibromatosis. Resection for symptomatic lesions should be offered.Intramedullary Tumors. Intramedullary tumors constitute approximately 5% of spinal tumors. They arise from within the parenchyma of the spinal cord. Common presenting symptoms are local dysesthesia, burning pain, radicular pain, sensory loss, weakness, or sphincter dysfunction. Patients with


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Surgery_Schwartz. arise from within the parenchyma of the spinal cord. Common presenting symptoms are local dysesthesia, burning pain, radicular pain, sensory loss, weakness, or sphincter dysfunction. Patients with such symp-toms should undergo MRI of the entire spine with and without enhancement.Ependymoma Ependymomas are the most common intramed-ullary tumors in adults. There are several histologic variants. The myxopapillary type occurs in the conus medullaris or the filum terminale in the lumbar region and has the best progno-sis after resection. The cellular type occurs more frequently in the cervical cord. Many spinal ependymomas have cystic areas and may contain hemorrhage. Surgical removal can improve function. A distinct tumor margin often exists, allowing safer excision. Postoperative radiation therapy after subtotal resection may prolong disease control.Astrocytoma Astrocytomas are the most common intramedul-lary tumors in children, although they also occur in adults. They may occur at all


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Surgery_Schwartz. therapy after subtotal resection may prolong disease control.Astrocytoma Astrocytomas are the most common intramedul-lary tumors in children, although they also occur in adults. They may occur at all levels, although more often in the cervical cord. The tumor may interfere with the CSF-containing central canal of the spinal cord, leading to a dilated central canal, referred to as syringomyelia (syrinx). Spinal astrocytomas are usually low grade, but complete excision is rarely possible due to the nonencapsulated, infiltrative nature of the tumor. As a result, patients with astrocytomas fare worse overall than patients with ependymomas.Other Tumors. Other types of rare tumors include high-grade astrocytomas, dermoids, epidermoids, teratomas, hemangiomas, hemangioblastomas, and metastases. Patients usually present with pain. Prognosis generally depends on preoperative func-tion and the histologic characteristics of the lesion.Future DirectionsFuture directions in the neurosurgical


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Surgery_Schwartz. Patients usually present with pain. Prognosis generally depends on preoperative func-tion and the histologic characteristics of the lesion.Future DirectionsFuture directions in the neurosurgical management of brain tumors are related to improved genetic characterization of brain tumors and technological advances. Regarding the former, the recent update of the World Health Organization classification of central nervous system tumors, alluded to earlier in this chap-ter, emphasizes an integrated classification approach utilizing both histologic and molecular characteristics.72 The addition of the latter feature underscores significant advances in the genet-ics of CNS tumors, which are being translated to treatment. Immunotherapy, for example, is an active area of research in the treatment of GBM. In this approach, immune cells such as T cells and dendritic cells are leveraged to target tumor-specific tissue. These approaches will play an important role as adjuvant therapy to


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Surgery_Schwartz. treatment of GBM. In this approach, immune cells such as T cells and dendritic cells are leveraged to target tumor-specific tissue. These approaches will play an important role as adjuvant therapy to neurosurgical approaches.Recent advances in neurosurgical technology are being used to address previous operative limitations. Intraoperative fluorescein is being studied as a means of marking abnor-mal tissue that appears grossly normal in order to maximize resection and minimize recurrence. Indications for SRS are expanding and provide a noninvasive option that can be used as monotherapy or as supplemental therapy to operative inter-vention. Moreover, new minimally invasive techniques, such as MRI-guided laser interstitial thermal therapy (MRgLITT), are actively being studied for less morbid access to otherwise difficult-to-reach tumors.SPINE: BASIC CONCEPTSThe spine is a complex structure and is subject to an extensive array of pathologic processes, including degeneration,


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Surgery_Schwartz. less morbid access to otherwise difficult-to-reach tumors.SPINE: BASIC CONCEPTSThe spine is a complex structure and is subject to an extensive array of pathologic processes, including degeneration, inflam-mation, infection, neoplasia, and trauma. Discussions of spine trauma, tumor, and infection are addressed separately in this chapter in the “Infection—Spine,” “Spinal Tumors,” and “Spine Trauma” sections. General concepts, common patterns of dis-ease, and basic operative interventions are presented here.The spine consists of a series of stacked vertebrae, inter-vening discs, and longitudinal ligaments. The vertebrae consist of the vertebral body anteriorly and the pedicles, articular facets, laminae, and spinous processes posteriorly. The intervertebral discs have two components. The tough, fibrous ring that runs around the outer diameter of the two adjacent vertebral bodies is known as the annulus fibrosus. The spongy material inside the ring of the annulus is known as the nucleus


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Surgery_Schwartz. fibrous ring that runs around the outer diameter of the two adjacent vertebral bodies is known as the annulus fibrosus. The spongy material inside the ring of the annulus is known as the nucleus pulposus. The annu-lus and the nucleus provide a cushion between adjacent verte-bral bodies, absorb forces transmitted to the spine, and allow some movement between the vertebral bodies. The ligaments stabilize the spine by limiting the motion of adjacent vertebrae.Stability and neural compression are the two concepts crit-ical to understanding the mechanics and pathologic processes affecting the spine.StabilityThe spinal column is the principal structural component of the axial spine, and it must bear significant loads. The vertebrae increase in size from the top to the bottom of the spine, cor-relating with the increased total loads that the more caudal ele-ments must bear. The cervical spine is the most mobile. Cervical stability depends greatly on the integrity of the ligaments that run


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Surgery_Schwartz. with the increased total loads that the more caudal ele-ments must bear. The cervical spine is the most mobile. Cervical stability depends greatly on the integrity of the ligaments that run from level to level. The thoracic spine is the least mobile, due to the stabilizing effect of the rib cage. The lumbar spine has relatively massive vertebrae, supports heavy loads, and has Brunicardi_Ch42_p1827-p1878.indd 186101/03/19 7:17 PM 1862SPECIFIC CONSIDERATIONSPART IIintermediate mobility. The sacral spine is fused together and has no intrinsic mobility. The load borne by the lumbar spine is transmitted to the sacrum, and then the pelvis through the sacro-iliac joints. The coccyx is the most inferior segment of the spine and has no significant contribution to load bearing or mobility.A stable spine is one that can bear normally experienced forces resulting from body mass, movement, and muscle con-traction, while maintaining normal structure and alignment. An unstable spine will shift


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Surgery_Schwartz. spine is one that can bear normally experienced forces resulting from body mass, movement, and muscle con-traction, while maintaining normal structure and alignment. An unstable spine will shift or sublux under these forces. The determinants of spinal stability vary throughout the cervical, thoracic, and lumbar portions. In elementary form, stability depends on the structural integrity of the hard, bony elements of the vertebral column, as well as the tensile integrity and security of the supporting ligamentous attachments. Plain X-rays and CT scans are sensitive for detecting bony defects such as frac-tures or subluxation, while MRI better detects disruptions of the soft tissues, including ligaments and intervertebral discs. Specific patterns of abnormalities seen on imaging studies may suggest or diagnose spinal instability.A common form of nontraumatic spinal instability is lum-bar spondylolisthesis, which is typically a forward slippage of a lumbar vertebra relative to the lower


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Surgery_Schwartz. suggest or diagnose spinal instability.A common form of nontraumatic spinal instability is lum-bar spondylolisthesis, which is typically a forward slippage of a lumbar vertebra relative to the lower vertebra on which it rests. This results from congenital or degenerative disruption of the pars interarticularis, the critical bridge of bone that spans adja-cent facet joints. In the setting of a pars defect, there is no solid bony connection between the adjacent vertebrae. The spine is unstable and anterior listhesis (slippage) may result. Patients typically present with severe low back pain that is exacerbated with movement and load bearing (mechanical low back pain). Radiculopathy in this setting indicates neuroforaminal compres-sion. Figure 42-27 demonstrates an L4 and L5 spondylolisthesis.Neural CompressionBesides providing a stable, central element of the body’s support structure, the spine also protects the spinal cord and nerve roots as they pass through the neural foramina to


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Surgery_Schwartz. CompressionBesides providing a stable, central element of the body’s support structure, the spine also protects the spinal cord and nerve roots as they pass through the neural foramina to form the peripheral nervous system. In a healthy spine, the spinal cord and nerve roots are suspended in CSF, free of mechanical compression. Patho-logic processes that can lead to CSF space impingement and neural compression include: hypertrophic degenerative changes in the intervertebral discs and facet joints, expansion of epidural masses such as tumors or abscesses, and subluxation (i.e., slip-page) of adjacent vertebral bodies. Subluxation may be due to trauma that exceeds the spine’s load-bearing capabilities and leads to structural failure, or chronic structural degradation by degenerative disease, infection, or tumor. Subluxation reduces the cross-sectional area of the central canal and the neural foramina (see Fig. 42-10B). Reduced central canal area can lead to myelop-athy. Reduced neural


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Surgery_Schwartz. infection, or tumor. Subluxation reduces the cross-sectional area of the central canal and the neural foramina (see Fig. 42-10B). Reduced central canal area can lead to myelop-athy. Reduced neural foraminal area can lead to radiculopathy.Myelopathy. Compression of the spinal cord can cause distur-bance of function known as myelopathy. This dysfunction may be secondary to the direct effects of compression, cord isch-emia due to reduced perfusion, or pathologic changes due to repeated cord trauma. These mechanisms lead to demyelination of the corticospinal tracts, which are long descending motor tracts. Corticospinal tract damage leads to upper motor neuron signs and symptoms, including hyperreflexia, spasticity, and weakness. These mechanisms also cause damage to the dorsal columns, which carry ascending proprioception, vibration, and two-point discrimination information. Loss of proprioception makes fine motor tasks and ambulation difficult.Radiculopathy. Compression of the nerve


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Surgery_Schwartz. carry ascending proprioception, vibration, and two-point discrimination information. Loss of proprioception makes fine motor tasks and ambulation difficult.Radiculopathy. Compression of the nerve roots causes distur-bance of root function, known as radiculopathy. Characteristic features of radiculopathy include lower motor neuron signs and symptoms (hyporeflexia, atrophy, and weakness) and sensory dis-turbances such as numbness or tingling sensations (paresthesias), burning sensations (dysesthesias), and shooting (radicular) pain. Myelopathy and radiculopathy often present together in diseases that involve the central canal and the neural foramina. This com-bination can lead to lower motor neuron dysfunction at the level of disease, and upper motor neuron dysfunction below that level.Patterns of DiseaseCervical Radiculopathy. The cervical nerve roots exit the central canal above the pedicle of the same-numbered verte-bra and at the level of the higher adjacent intervertebral disc. For


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Surgery_Schwartz. of DiseaseCervical Radiculopathy. The cervical nerve roots exit the central canal above the pedicle of the same-numbered verte-bra and at the level of the higher adjacent intervertebral disc. For example, the C6 nerve root passes above the C6 pedicle at the level of the C5–C6 discs. The cervical nerve roots may be compressed acutely by disc herniation, or chronically by hypertrophic degenerative changes of the discs, facets, and liga-ments. Table 42-6 summarizes the effects of various disc her-niations. Most patients with acute disc herniations will improve without surgery. NSAIDs or cervical traction may help alle-viate symptoms. Patients whose symptoms do not resolve or who have significant weakness should undergo decompressive surgery. The two main options for nerve root decompression are anterior cervical discectomy and fusion (ACDF) and posterior cervical foraminotomy (keyhole foraminotomy). ACDF allows more direct access to and removal of the pathology (anterior to the nerve


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Surgery_Schwartz. are anterior cervical discectomy and fusion (ACDF) and posterior cervical foraminotomy (keyhole foraminotomy). ACDF allows more direct access to and removal of the pathology (anterior to the nerve root). However, the procedure requires fusion because discectomy causes a collapse of the interbody space and instabil-ity will likely occur. Figure 42-28 demonstrates a C6–C7 ACDF with the typical interposed graft and plating system. Keyhole foraminotomy allows for decompression without requiring Figure 42-27. Lateral lumbar spine X-ray demonstrates a 25% anterior slippage of L4 on L5 due to a defect in the L4 pars interar-ticularis. This is called spondylolisthesis.Brunicardi_Ch42_p1827-p1878.indd 186201/03/19 7:17 PM 1863NEUROSURGERYCHAPTER 42Table 42-6Cervical disc herniations and symptoms by levelLEVELFREQUENCY (%)ROOT INJUREDREFLEXWEAKNESSNUMBNESSC4–C52C5—DeltoidShoulderC5–C619C6BicepsBiceps brachiiThumbC6–C769C7TricepsWrist extensors (wrist drop)Second and third


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Surgery_Schwartz. and symptoms by levelLEVELFREQUENCY (%)ROOT INJUREDREFLEXWEAKNESSNUMBNESSC4–C52C5—DeltoidShoulderC5–C619C6BicepsBiceps brachiiThumbC6–C769C7TricepsWrist extensors (wrist drop)Second and third digitsC7–T110C8—Hand intrinsicsFourth and fifth digitsAdapted with permission from Greenberg MS. Handbook of Neurosurgery, 7th ed. New York, NY: Thieme; 2010.BAFigure 42-28. A. Anteroposterior cervical spine X-ray showing the position of an anterior cervical plate used for stabilization after C6–C7 discectomy. Patient presented with right triceps weakness and dysesthesias in the right fifth digit. Magnetic resonance imaging revealed a right paracentral C6–C7 herniated disc compressing the exiting C7 nerve root. B. Lateral cervical spine X-ray of the same patient clearly demonstrates the position of the plate and screws. The allograft bone spacer placed in the drilled-out disc space is also apparent.fusion, but it is less effective for removing centrally located canal pathology.Cervical


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Surgery_Schwartz. of the plate and screws. The allograft bone spacer placed in the drilled-out disc space is also apparent.fusion, but it is less effective for removing centrally located canal pathology.Cervical Spondylotic Myelopathy. The term spondylosis refers to diffuse degenerative and hypertrophic changes of the discs, intervertebral joints, and ligaments, which collectively result in spinal stenosis. Spinal cord dysfunction (myelopathy) due to cord compression from cervical spinal degenerative dis-ease is therefore referred to as cervical spondylotic myelopathy (CSM). Classically CSM presents with spasticity and hyper-reflexia due to corticospinal tract dysfunction, upper extremity weakness and atrophy from degeneration of the motor neu-rons in the anterior horns of the spinal gray matter, and loss of lower extremity proprioception due to dorsal column injury. Figure 42-29 demonstrates typical findings. Some patients com-plain of difficulty buttoning shirts, using utensils, and ambulating.


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Surgery_Schwartz. of lower extremity proprioception due to dorsal column injury. Figure 42-29 demonstrates typical findings. Some patients com-plain of difficulty buttoning shirts, using utensils, and ambulating. Spondylosis is usually diffuse, so the usual treatment for CSM is multilevel (usually C3–C7) cervical laminectomy, although patients with disease localized over one to three levels may be can-didates for anterior decompression and fusion. Fig. 42-30 demon-strates the postoperative appearance of a vertebral corpectomy and fusion for CSM. Thorough cervical laminectomy decompresses the cord posteriorly. Patients often have slow recovery due to the extensive chronic changes in the cervical cord and may benefit from rehabilitation programs. The other disease that classically presents with combined upper and lower motor neuron symp-toms is amyotrophic lateral sclerosis (ALS). Care must be taken Brunicardi_Ch42_p1827-p1878.indd 186301/03/19 7:17 PM 1864SPECIFIC CONSIDERATIONSPART IIto avoid


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Surgery_Schwartz. upper and lower motor neuron symp-toms is amyotrophic lateral sclerosis (ALS). Care must be taken Brunicardi_Ch42_p1827-p1878.indd 186301/03/19 7:17 PM 1864SPECIFIC CONSIDERATIONSPART IIto avoid offering cervical laminectomy to a patient with undi-agnosed ALS. Two findings help differentiate CSM from ALS: cranial nerve dysfunction such as dysphagia (not typically caused by cervical spine disease) and sensory disturbance (not found in ALS).Thoracic Disc Herniation. Thoracic disc herniation accounts for <1% of herniated discs. A patient may present with radicular pain or sensorimotor changes in the lower extremities due to cord compression. A posterior approach via midline incision and lami-nectomy should be avoided because of the high incidence of cord injury from manipulation and retraction. Anterior approaches via thoracotomy minimize risk to the cord and allow excellent access to the disc. The radicular arteries running from the aorta to the thoracic cord should be spared, when


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Surgery_Schwartz. Anterior approaches via thoracotomy minimize risk to the cord and allow excellent access to the disc. The radicular arteries running from the aorta to the thoracic cord should be spared, when possible, to avoid ischemia. Alternatively, a posterolateral approach is possible via resection of the rib head and facet joint. Finally, a transpedicular approach may be attempted for lateral disc herniations.73Lumbar Radiculopathy. Lumbar nerve roots exit the thecal sac, pass over the higher adjacent disc space, and exit the canal under the pedicle of the same-numbered vertebra. Therefore, the L5 nerve root passes over the L4–L5 disc space and exits under the L5 pedicle (Fig. 42-31). Lumbar discs may herniate with or without a history of trauma or straining. Normally they cause lancinating (radicular) pain down the leg (Table 42-7). Most acute herniated lumbar discs improve symptomatically without surgery. Surgery is indicated for symptoms persisting more than 6 to 8 weeks, progressive motor


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Surgery_Schwartz. pain down the leg (Table 42-7). Most acute herniated lumbar discs improve symptomatically without surgery. Surgery is indicated for symptoms persisting more than 6 to 8 weeks, progressive motor deficit (e.g., foot drop), or for patients with incapacitating pain not manage-able with analgesics. A recent randomized control trial (Spine Patients Outcome Research Trial [SPORT])74 did not observe significant differences between patients randomized to undergo surgery vs. conservative management when using an intent-to-treat analysis. Because of the high amount of bi-directional cross-over between the surgery and conservative group, a sub-sequent reanalysis of the data as observational cohort analysis, demonstrated improved functional outcomes in terms of pain and physical function, more so at 3 months than at 2 years.74Discectomy is performed using a midline incision, partial removal of the overlying laminae (hemilaminectomy or lami-notomy), identification of the thecal sac and nerve root,


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Surgery_Schwartz. months than at 2 years.74Discectomy is performed using a midline incision, partial removal of the overlying laminae (hemilaminectomy or lami-notomy), identification of the thecal sac and nerve root, and extraction of disc fragments. Free-floating disc fragments may be found. Often, however, the herniated disc material is still contained within the annulus, requiring incision of the poste-rior longitudinal ligament and curettage of the disc space. After lumbar discectomy, approximately two-thirds of patients will have complete relief of pain, and up to 85% will have significant improvement.Neurogenic Claudication. Neurogenic claudication is char-acterized by low back and leg pain that occurs while walking and is relieved by stopping, leaning forward, or sitting. It is normally caused by degenerative lumbar stenosis causing com-pression of the cauda equina. Neurogenic claudication must be distinguished from vascular claudication, which tends to resolve quickly with cessation of walking.


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Surgery_Schwartz. lumbar stenosis causing com-pression of the cauda equina. Neurogenic claudication must be distinguished from vascular claudication, which tends to resolve quickly with cessation of walking. There is typically no need to change position, and the pain follows a stocking distribution rather than a dermatomal distribution. Pallor and coldness of the feet, and normal neurologic examination are also typical, though diabetic patients may present a challenge with microvascular Figure 42-29. T2-weighted sagittal magnetic resonance imaging of the cervical spine showing multilevel degenerative changes caus-ing spinal stenosis that is worst at C5–C6. Note the bright signal within the cord at that level, consistent with myelopathy.Figure 42-30. Lateral cervical spine X-ray status post C5 corpec-tomy for cervical spondylotic myelopathy. This involves removal of the C4–C5 disc, C5 vertebral body, and C5–C6 disc, decom-pressing at two levels. A bone strut is visible bridging C4 to C6. The plate and


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Surgery_Schwartz. for cervical spondylotic myelopathy. This involves removal of the C4–C5 disc, C5 vertebral body, and C5–C6 disc, decom-pressing at two levels. A bone strut is visible bridging C4 to C6. The plate and screws stabilize the segments.Brunicardi_Ch42_p1827-p1878.indd 186401/03/19 7:17 PM 1865NEUROSURGERYCHAPTER 42neuropathy. Patients with neurogenic claudication have a slowly progressive course and may be surgical candidates when their pain interferes with their lifestyle. The usual surgery is an L3 to L5 lumbar laminectomy to decompress the nerve roots. A recent randomized control trial did not observe a significant difference in outcomes between surgical and conservative management of lumbar stenosis at 1 year.75 Thus, surgical management of lum-bar stenosis should be reserved for patients that do not improve with physical therapy.Cauda Equina Syndrome. Cauda equina syndrome is due to compression of the cauda equina and may result from massive disc herniation, EDH, epidural abscess,


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Surgery_Schwartz. that do not improve with physical therapy.Cauda Equina Syndrome. Cauda equina syndrome is due to compression of the cauda equina and may result from massive disc herniation, EDH, epidural abscess, tumor, or subluxation from trauma. Patients with cauda equina compression often present with urinary retention, saddle anesthesia, or progressing leg weakness. Saddle anesthesia is numbness in the perineum, genitals, buttocks, and upper inner thighs. Patients with sus-pected cauda equina syndrome should undergo immediate MRI of the lumbar spine to evaluate for a surgical lesion. Mass lesions should be removed urgently via laminectomy to preserve sphincter function and ambulation.Spine Fusion SurgeryFusion surgery is often required for patients with spinal instabil-ity resulting from disease, surgical intervention, or both. Fusion procedures lock adjacent vertebrae together. Fusion occurs when the body forms a solid mass of bone incorporating the adjacent vertebrae, eliminating normal


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Surgery_Schwartz. surgical intervention, or both. Fusion procedures lock adjacent vertebrae together. Fusion occurs when the body forms a solid mass of bone incorporating the adjacent vertebrae, eliminating normal intervertebral move-ment. Stabilization and immobilization promote bony fusion. Internal instrumentation and external orthoses are often used to stabilize and immobilize the fused spinal segments.Spinal InstrumentationInternal fixation devices for spinal segmental immobilization have been developed for all levels of the spine. Most spinal instrumentation constructs have two elements. The first element is a device that solidly attaches to the vertebral bodies. Options include wires wrapped around laminae or spi-nous processes, hooks placed under the lamina or around the pedicles, or screws placed in the pedicles or the vertebral bodies. The second element is a device that traverses vertebral seg-ments. Options include rods and plates that lock directly to the wires, hooks, or screws at each


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Surgery_Schwartz. in the pedicles or the vertebral bodies. The second element is a device that traverses vertebral seg-ments. Options include rods and plates that lock directly to the wires, hooks, or screws at each vertebral level. Spinal instru-mentation devices are available for anterior and posterior fusion in the cervical, thoracic, and lumbar regions. Most modern spi-nal instrumentation devices are made of titanium to minimize problems with future MRI scanning (Fig. 42-32). All spinal instrumentation constructs will eventually fail by loosening or breaking if bony fusion does not occur.6ABFigure 42-31. A. T2-weighted sagittal magnetic resonance imaging shows an L5–S1 disc herniation causing significant canal compromise and displacement of nerve roots. B. T2-weighted axial magnetic resonance imaging of the same patient shows the large left paracentral disc herniation at L5–S1. Arrowheads delineate the extent of the herniation. The arrow indicates the right S1 nerve root passing through free of


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Surgery_Schwartz. of the same patient shows the large left paracentral disc herniation at L5–S1. Arrowheads delineate the extent of the herniation. The arrow indicates the right S1 nerve root passing through free of compression. The left S1 nerve root is under severe compression and is not seen.Table 42-7Lumbar disc herniations and symptoms by levelLEVELFREQUENCY (%)ROOT INJUREDREFLEXWEAKNESSNUMBNESSL3–L45L4PatellarQuadricepsAnterior thighL4–L545L5—Tibialis anterior (foot drop)Great toeL5–S150S1AchillesGastrocnemiusLateral footAdapted with permission from Greenberg MS. Handbook of Neurosurgery, 7th ed. New York, NY: Thieme; 2010.Brunicardi_Ch42_p1827-p1878.indd 186501/03/19 7:17 PM 1866SPECIFIC CONSIDERATIONSPART IIFigure 42-32. A. Lateral lumbar spine X-ray showing pedicle screws and connecting rods used to stabilize L4 with respect to L5. This instrumentation was placed as part of a fusion operation to stabilize progressive L4–L5 spondylolisthesis with intractable low back pain. B.


Surgery_Schwartz

Surgery_Schwartz. rods used to stabilize L4 with respect to L5. This instrumentation was placed as part of a fusion operation to stabilize progressive L4–L5 spondylolisthesis with intractable low back pain. B. Anteroposterior lumbar spine X-ray showing L3 to L5 instrumentation with pedicle screws and connecting rods. The patient had previously sustained an L4 burst fracture. Note the sig-nificant loss of height of the L4 body compared to adjacent levels. The small row of staples to the right delineates the incision over the iliac crest used to harvest cancellous bone as a nonstructural osteoinductive autograft fusion designed to induce formation of a solid bone bridge from L3 to L5 (arthrodesis).ArthrodesisArthrodesis refers to the obliteration of motion or instability by incorporating the relevant components into a solid mass of bone. Arthrodesis must occur in any fused segment to have long-term stability. Failure of arthrodesis results in failed fusion, often in the form of a fibrous nonunion. The


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Surgery_Schwartz. into a solid mass of bone. Arthrodesis must occur in any fused segment to have long-term stability. Failure of arthrodesis results in failed fusion, often in the form of a fibrous nonunion. The rates of successful fusion are higher in the cervical spine than the lum-bar spine. Arthrodesis requires ingrowth of new bone formed by the patient’s osteoblasts across the unstable defect. Insert-ing graft material, such as autograft or allograft, into the defect provides a bridge for osteoblasts and promotes fusion. The term autograft refers to the patient’s own bone, often harvested from the iliac crest. Iliac crest bone graft is a source of both cortical and cancellous bone. Cortical bone provides structural support, while cancellous bone provides a matrix for bony ingrowth. The term allograft refers to sterilized bone from human tissue banks. Allografts also may be cortical, cancellous, or both. Allograft lacks the array of osteoinductive endogenous compounds intrinsic to autograft,


Surgery_Schwartz

Surgery_Schwartz. refers to sterilized bone from human tissue banks. Allografts also may be cortical, cancellous, or both. Allograft lacks the array of osteoinductive endogenous compounds intrinsic to autograft, although supplemental products such as demineralized bone matrix paste can be added to encourage new bone formation. Other techniques for increasing the rates of suc-cessful fusion are being developed, including the integration of osteoinductive bone morphogenetic proteins, known as BMPs, into the fusion constructs.Dynamic stabilization refers to the creation of spinal sta-bility without achieving a bony fusion. The concept applies to both cervical and lumbar motion segments. Artificial lumbar and cervical disc replacement therapies are recent developments in degenerative spine disease that address this concept. How-ever, their use is limited to very select cases. Another motion preservation technique that may hold promise is segmental “soft” stabilization.77 In cases of degenerative


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Surgery_Schwartz. address this concept. How-ever, their use is limited to very select cases. Another motion preservation technique that may hold promise is segmental “soft” stabilization.77 In cases of degenerative spondylolisthe-sis, such systems in the lumbar spine allow for decompressive laminectomy without increasing slippage. In theory, adjacent level facets and discs are spared the stresses of a neighboring bony fusion moment arm.PERIPHERAL NERVECommon pathologic processes that compromise function of the peripheral nervous system include mechanical compression, ischemia, inflammation, and neoplasia.Peripheral Nerve TumorsMost peripheral nerve tumors are benign and grow slowly. Significant pain increases the likelihood that the patient has a malignant tumor. Treatment for peripheral nerve tumors is sur-gical resection to establish diagnosis and evaluate for signs of malignancy. These tumors have various degrees of involvement with the parent nerve. Some can be resected with minimal or no damage to


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Surgery_Schwartz. resection to establish diagnosis and evaluate for signs of malignancy. These tumors have various degrees of involvement with the parent nerve. Some can be resected with minimal or no damage to the nerve. Tumors that grow within the nerve often contain functioning fascicles. Total excision of these tumors requires sacrifice of the parent nerve. The choice of subtotal resection, nerve preservation, and observation, vs. total resec-tion with nerve sacrifice depends on tumor histology and the function of the parent nerve.Schwannoma. Schwannomas are the most common peripheral nerve tumors, also referred to as neurilemomas or neurinomas. Most occur in the third decade of life. These benign tumors arise from Schwann cells, which form myelin in peripheral nerves. The most characteristic presentation is a mass lesion with point tenderness and shooting pains on direct palpation. Spontaneous ABBrunicardi_Ch42_p1827-p1878.indd 186601/03/19 7:17 PM 1867NEUROSURGERYCHAPTER 42or continuous pain


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Surgery_Schwartz. is a mass lesion with point tenderness and shooting pains on direct palpation. Spontaneous ABBrunicardi_Ch42_p1827-p1878.indd 186601/03/19 7:17 PM 1867NEUROSURGERYCHAPTER 42or continuous pain suggests malignancy. Schwannomas tend to grow slowly and eccentrically on parent nerves. The eccentric location and discrete encapsulated nature of these tumors often allow total resection without significant damage to the parent nerve. Subtotal resection and observation is reasonable for schwannomas entwined in important nerves, as the incidence of malignant transformation is extremely low.Neurofibroma. Neurofibromas arise within the nerve and tend to be fusiform masses, unlike schwannomas, which tend to grow out of the nerve. Neurofibromas often present as a mass that is tender to palpation. They usually lack the shooting pains char-acteristic of schwannomas. Neurofibromas are often difficult to resect completely without sacrifice of the parent nerve. Neuro-fibromas have a higher incidence


Surgery_Schwartz

Surgery_Schwartz. usually lack the shooting pains char-acteristic of schwannomas. Neurofibromas are often difficult to resect completely without sacrifice of the parent nerve. Neuro-fibromas have a higher incidence of malignant transformation; therefore, patients with known residual tumors require close observation. Patients with NF1 often have multiple neurofibro-mas. These patients should be offered resection for symptomatic tumors. Risk of malignant degeneration is up to 10%. Malignant neurofibromas have the histologic characteristics of sarcoma.Malignant Nerve Sheath Tumors. Malignant nerve sheath tumors include solitary sarcomas, degenerated neurofibromas, and neuroepitheliomas. Patients with malignant peripheral nerve tumors typically complain of constant pain, rather than pain only on palpation, and are more likely to have motor and sensory deficits in the distribution of the parent nerve. Treat-ment for these tumors is radical excision. This often requires sacrifice of the parent nerve.


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Surgery_Schwartz. and are more likely to have motor and sensory deficits in the distribution of the parent nerve. Treat-ment for these tumors is radical excision. This often requires sacrifice of the parent nerve. Invasion of nearby soft tissues may occur and necessitate wide resection or amputation in an attempt to prevent systemic metastasis.Entrapment NeuropathiesEntrapment neuropathy presents as neurologic dysfunction in nerves passing through a pathologically small, fixed space. Nerve dysfunction may result directly from chronic, repetitive pressure on the nerve, or from ischemic damage due to impaired perfusion.77 Entrapment causing dysfunction of nerve signaling may be associated with numbness, paresthesias, weakness, or muscle atrophy. The two most common sites of entrapment neu-ropathy are the ulnar nerve at the medial aspect of the elbow and the median nerve at the wrist. Usually EMG/NCS demon-strate slowing across the entrapped segment of nerve. Mechani-cal peripheral nerve disorders


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Surgery_Schwartz. the ulnar nerve at the medial aspect of the elbow and the median nerve at the wrist. Usually EMG/NCS demon-strate slowing across the entrapped segment of nerve. Mechani-cal peripheral nerve disorders resulting from trauma (brachial plexus disruption, radial nerve damage from humerus fractures, and common peroneal nerve crush injuries) are discussed in the section “Trauma.”Ulnar Neuropathy. The ulnar nerve has contributions from the C7, C8, and T1 nerve roots, arises from the medial cord of the brachial plexus, and supplies most of the intrinsic hand mus-cles (interossei and third and fourth lumbricals) and sensation to the fourth and fifth digits. It passes posteriorly to the medial epicondyle at the elbow in the condylar groove. This segment is superficial and subject to external compression and repeti-tive minor impacts. Patients with ulnar entrapment at the elbow present with numbness and tingling in the medial palm, as well as the fourth and fifth digits. Motor deficits include


Surgery_Schwartz

Surgery_Schwartz. and repeti-tive minor impacts. Patients with ulnar entrapment at the elbow present with numbness and tingling in the medial palm, as well as the fourth and fifth digits. Motor deficits include weakness and wasting of the intrinsic hand muscles. Treatment for symp-tomatic ulnar entrapment neuropathy is surgical exploration and incision of the fibrous aponeurotic arch that overlies the nerve. A 6-cm curvilinear incision centered between the medial epi-condyle and the olecranon allows exploration of up to 10 cm of nerve and lysis of compressive tissues.Carpal Tunnel Syndrome. The median nerve has contribu-tions from the C5 to T1 nerve roots, arises from the medial and lateral cords of the brachial plexus, and supplies the muscles of wrist and finger flexion and sensation to the palmar aspect of the first, second, and third digits. The median nerve passes through the carpal tunnel in the wrist, lying superficial to the four deep and four superficial flexor tendons. The transverse carpal


Surgery_Schwartz

Surgery_Schwartz. of the first, second, and third digits. The median nerve passes through the carpal tunnel in the wrist, lying superficial to the four deep and four superficial flexor tendons. The transverse carpal liga-ment is a tough, fibrous band that forms the roof of the carpal tunnel. The ligament attaches to the pisiform and hamate medi-ally and the trapezium and scaphoid laterally. Patients complain of numbness and tingling in the supplied digits, clumsiness, and worsening with sleep or repetitive wrist movement. Patients may notice wasting of the thenar eminence. Treatment for symptomatic carpal tunnel syndrome unresponsive to splinting, analgesics, and rest is surgical division of the flexor retinacu-lum. This often provides prompt relief of pain symptoms and slow recovery of numbness and strength.Autoimmune and Inflammatory DisordersThese are not surgical diseases, but they merit brief mention as they are included in the differential diagnosis for new-onset weakness. Their characteristic


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Surgery_Schwartz. and Inflammatory DisordersThese are not surgical diseases, but they merit brief mention as they are included in the differential diagnosis for new-onset weakness. Their characteristic presentations help distinguish them from weakness due to structural lesions.Guillain-Barré Syndrome. Guillain-Barré syndrome is an acute inflammatory demyelinating polyradiculopathy often occurring after viral infection, surgery, inoculations, or myco-plasma infections. Patients classically present with weakness ascending from the legs to the body, arms, and even cranial nerves. Symptoms usually progress over 2 to 4 weeks and then resolve. Care is supportive. Respiratory weakness may require ventilatory support.Myasthenia Gravis. Myasthenia gravis is an autoimmune process in which antibodies form to the acetylcholine recep-tors of muscles, leading to fluctuating weakness. Most patients have either thymic hyperplasia or thymoma. The most common symptoms are diplopia, ptosis, dysarthria, and dysphagia.


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Surgery_Schwartz. recep-tors of muscles, leading to fluctuating weakness. Most patients have either thymic hyperplasia or thymoma. The most common symptoms are diplopia, ptosis, dysarthria, and dysphagia. More severe cases have limb or respiratory involvement. Weakness worsens with repetitive movement. Treatment is with acetylcho-linesterase inhibitors and possible thymectomy.Eaton-Lambert Syndrome. Eaton-Lambert syndrome is an autoimmune process with antibodies to the presynaptic calcium channels. This is a paraneoplastic syndrome most commonly associated with oat cell carcinoma. Patients have weakness of proximal limb muscles that improves with repetitive movement. This diagnosis must prompt oncologic evaluation.INFECTIONCNS infections of interest to neurosurgeons include those that cause focal neurologic deficit due to mass effect, require surgi-cal aspiration or drainage because antibiotic therapy alone is insufficient, cause mechanical instability of the spine, or occur after neurosurgical


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Surgery_Schwartz. deficit due to mass effect, require surgi-cal aspiration or drainage because antibiotic therapy alone is insufficient, cause mechanical instability of the spine, or occur after neurosurgical procedures.CranialOsteomyelitis. The skull is highly vascular and resistant to infections. Osteomyelitis of the skull may develop by contigu-ous spread from pyogenic sinus disease or from contamination by penetrating trauma. Staphylococcus aureus and S epidermidis are the most frequent causative organisms. Patients usually present with redness, swelling, and pain. Contrast head CT aids 7Brunicardi_Ch42_p1827-p1878.indd 186701/03/19 7:17 PM 1868SPECIFIC CONSIDERATIONSPART IIdiagnosis and shows the extent of involved bone, along with associated abscesses or empyema. Osteomyelitis treatment entails surgical debridement of involved bone followed by 2 to 4 months of antibiotics. Craniotomy wound infections are a special concern because performing a craniotomy creates a devascularized free bone


Surgery_Schwartz

Surgery_Schwartz. surgical debridement of involved bone followed by 2 to 4 months of antibiotics. Craniotomy wound infections are a special concern because performing a craniotomy creates a devascularized free bone flap susceptible to infection and not penetrated by antibiotics. These wounds must be debrided and the bone flaps removed and discarded. Subsequent care involves appropriate antibiotic therapy, observation for signs of recurrent infection off antibiotics, and return to the OR for titanium or methylmethacrylate cranioplasty 6 to 12 months later.Subdural Empyema. Subdural empyema is a rapidly progres-sive pyogenic infection. The subdural space lacks significant barriers to the spread of the infection, such as compartmental-ization or septations. Subdural empyemas usually occur over the cerebral convexities. Potential infectious sources include sinus disease, penetrating trauma, and otitis. Streptococci and staphylococci are the most frequent sources. Presenting symp-toms include fever,


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Surgery_Schwartz. convexities. Potential infectious sources include sinus disease, penetrating trauma, and otitis. Streptococci and staphylococci are the most frequent sources. Presenting symp-toms include fever, headache, neck stiffness, seizures, or focal neurologic deficit. Neurologic deficit results from inflammation of cortical blood vessels, leading to thrombosis and stroke. The most common deficit is contralateral hemiparesis. Patients with suggestive symptoms should undergo rapid contrast CT scan. LP frequently fails to yield the offending organism and risks herniation due to mass effect. Typical treatment is wide hemi-craniectomy, dural opening, and lavage. The pus may be thick or septated, making burr hole drainage or small craniotomy insufficient. Patients then require 1 to 2 months of antibiotics. Subdural empyema has 10% to 20% mortality risk and common chronic sequelae, including development of a seizure disorder and residual hemiparesis. However, many patients do make a good


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Surgery_Schwartz. of antibiotics. Subdural empyema has 10% to 20% mortality risk and common chronic sequelae, including development of a seizure disorder and residual hemiparesis. However, many patients do make a good recovery.Brain Abscess. Brain abscess is encapsulated infection within the brain parenchyma. It may spread hematogenously in patients with endocarditis or intracardiac or intrapulmonary right-to-left shunts, by migration from the sinuses or ear, or via direct seed-ing by penetrating trauma. Disorganized cerebritis often pre-cedes formation of the organized, walled-off abscess. Patients may present with nonspecific symptoms such as headache, nau-sea, or lethargy, or with focal neurologic deficit such as hemi-paresis. Alternatively, patients may present in extremis if the abscess ruptures into the ventricular system. Abscesses appear as well-demarcated, ring-enhancing, thin-walled lesions on CT scan and MRI, and often have associated edema and mass effect. Patients require antibiotic


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Surgery_Schwartz. into the ventricular system. Abscesses appear as well-demarcated, ring-enhancing, thin-walled lesions on CT scan and MRI, and often have associated edema and mass effect. Patients require antibiotic therapy after needle aspira-tion or surgical evacuation. Antibiotic therapy without surgical evacuation may be considered for patients with small, multiple, or critically located abscesses. Abscesses that are large, cause mass effect, decreased mental status, or that fail to decrease in size after 1 week of antibiotics, should be evacuated. Nonsurgical management still requires aspiration or biopsy specimen for organism culture and sensitivities. Blood and CSF cultures rarely give definitive diagnosis. Removal of an encapsulated abscess significantly shortens the length of antibiotic therapy required to eliminate all organisms. Common chronic sequelae after suc-cessful treatment include seizures or focal neurologic deficit.SpinePyogenic Vertebral Osteomyelitis. Pyogenic vertebral


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Surgery_Schwartz. therapy required to eliminate all organisms. Common chronic sequelae after suc-cessful treatment include seizures or focal neurologic deficit.SpinePyogenic Vertebral Osteomyelitis. Pyogenic vertebral osteomyelitis is a destructive bacterial infection of the vertebrae, usually of the vertebral body. Vertebral osteomyelitis frequently results from hematogenous spread of distant disease, but may occur as an extension of adjacent disease, such as psoas abscess or perinephric abscess. S aureus and Enterobacter spp. are the most frequent etiologic organisms. Patients usually present with fever and back pain. Diabetics, IV drug abusers, and dialysis patients have increased incidence of vertebral osteomyelitis. Epidural extension may lead to compression of the spinal cord or nerve roots with resultant neurologic deficit. Osteomyelitis presents a lytic picture on imaging and must be distinguished from neoplastic disease. Adjacent intervertebral disc involve-ment occurs frequently with pyogenic


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Surgery_Schwartz. neurologic deficit. Osteomyelitis presents a lytic picture on imaging and must be distinguished from neoplastic disease. Adjacent intervertebral disc involve-ment occurs frequently with pyogenic osteomyelitis, but rarely with neoplasia. Plain films and CT help assess the extent of bony destruction or deformity such as kyphosis. MRI shows adjacent soft tissue or epidural disease. Most cases can be treated suc-cessfully with antibiotics alone, although the organism must be isolated to steer antibiotic choice. Blood cultures may be positive. Surgical intervention may be required for debridement when antibiotics alone fail, or for stabilization and fusion in the setting of instability and deformity.Tuberculous Vertebral Osteomyelitis. Tuberculous verte-bral osteomyelitis, also known as Pott’s disease, occurs most commonly in underdeveloped countries and in the immuno-compromised. Several features differentiate tuberculous osteo-myelitis from bacterial osteomyelitis. The infection is


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Surgery_Schwartz. disease, occurs most commonly in underdeveloped countries and in the immuno-compromised. Several features differentiate tuberculous osteo-myelitis from bacterial osteomyelitis. The infection is indolent and symptoms often progress slowly over months. Tuberculosis rarely involves the intervertebral disc. The involved bodies may have sclerotic rather than lytic changes. Multiple nonadjacent vertebrae may be involved. The upper lumbar and lower tho-racic vertebrae are most commonly affected. Diagnosis requires documentation of acid-fast bacilli. Treatment involves long-term antimycobacterial drugs. Patients with spinal instability or neural compression from epidural inflammatory tissue should undergo debridement and fusion as needed.Discitis. Primary infection of the intervertebral disc space, or discitis, is most commonly secondary to postoperative infec-tions. Spontaneous discitis occurs more commonly in children. S aureus and S epidermidis account for most cases. The pri-mary symptom


Surgery_Schwartz

Surgery_Schwartz. or discitis, is most commonly secondary to postoperative infec-tions. Spontaneous discitis occurs more commonly in children. S aureus and S epidermidis account for most cases. The pri-mary symptom is back pain. Other signs and symptoms include radicular pain, fevers, paraspinal muscle spasm, and localized tenderness to palpation. Many cases will resolve without anti-biotics, which generally are given for positive blood or biopsy specimen cultures or persistent constitutional symptoms. Most patients will have spontaneous fusion across the involved disc and do not need debridement or fusion.Epidural Abscess. Epidural abscesses may arise from or spread to the adjacent bone or disc, so distinguishing between vertebral osteomyelitis or discitis and a spinal epidural abscess may be difficult. The most common presenting signs and symp-toms are back pain, fever, and tenderness to palpation of the spine. The most significant risk of epidural abscess is weakness progressing to paralysis due to


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Surgery_Schwartz. most common presenting signs and symp-toms are back pain, fever, and tenderness to palpation of the spine. The most significant risk of epidural abscess is weakness progressing to paralysis due to spinal cord or nerve root dam-age. Cord and root damage may be due to direct compression or to inflammatory thrombosis resulting in venous infarction. S aureus and Streptococcus spp. are the most common organisms. Methicillin-resistant S aureus now constitutes a significant pro-portion of these infections, as high as 40%.78 The source may be hematogenous spread, local extension, or operative contamina-tion. MRI best demonstrates the epidural space and degree of neural compromise. Patients with spinal epidural abscess and neurologic compromise should undergo surgical debridement for decompression and diagnosis, followed by culture-directed Brunicardi_Ch42_p1827-p1878.indd 186801/03/19 7:17 PM 1869NEUROSURGERYCHAPTER 42antibiotic therapy. Relative contraindications to surgery include


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Surgery_Schwartz. and diagnosis, followed by culture-directed Brunicardi_Ch42_p1827-p1878.indd 186801/03/19 7:17 PM 1869NEUROSURGERYCHAPTER 42antibiotic therapy. Relative contraindications to surgery include prohibitive comorbidities or total lack of neurologic function below the involved level. Patients with no neurologic deficits and an identified organism may be treated with antibiotics alone and very close observation. However, this management strat-egy remains somewhat controversial because these patients can undergo rapid and irreversible neurologic decline. Most epidural abscesses can be accessed via laminectomy without fusion. Col-lections predominantly anterior to the cervical or thoracic cord may require anterior approach and fusion.FUNCTIONAL NEUROSURGERYEpilepsy SurgerySeizures result from uncontrolled neuronal electrical activity. Seizures may result from irritative lesions in the brain, such as tumors or hematomas, or from physiologic or structural abnor-malities. Seizures may involve


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Surgery_Schwartz. neuronal electrical activity. Seizures may result from irritative lesions in the brain, such as tumors or hematomas, or from physiologic or structural abnor-malities. Seizures may involve a part of the brain (focal) or the entire brain (generalized). Focal seizures may be associated with normal consciousness (simple) or decreased conscious-ness (complex). All generalized seizures cause loss of con-sciousness. Focal seizures may secondarily generalize. Patients with multiple unprovoked seizures over time are considered to have epilepsy. The type of epilepsy depends on such factors as type of seizures, electroencephalographic (EEG) findings, associated syndromes, and identifiable etiologies. All patients with unexplained seizures (i.e., no obvious cause such as head trauma or alcohol withdrawal) require thorough neurologic evaluation, including imaging to evaluate for a mass lesion. Antiepileptic drugs (AEDs) form the first line of therapy for epilepsy, initially as monotherapy, then as


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Surgery_Schwartz. require thorough neurologic evaluation, including imaging to evaluate for a mass lesion. Antiepileptic drugs (AEDs) form the first line of therapy for epilepsy, initially as monotherapy, then as combination ther-apy. Epilepsy patients who have failed satisfactory trials of sev-eral AED combination regimens may be candidates for surgical intervention. Lack of seizure control or patient intolerance of the medications may constitute failure. Epilepsy surgery can decrease the frequency of seizures by resection of the electrical source of the seizures, or decrease the severity of seizures by disconnecting white matter tracts through which the abnormal electrical activity spreads. Four types of epilepsy surgery are discussed in sections that follow. Epilepsy surgery appears to be extremely underused, given the relatively low risk of the procedures, and the crippling social and economic effects of uncontrolled or partially controlled epilepsy.79 Patients with symptoms, imaging abnormalities,