Neurology-Related Definitions

A - B

Acoustic Neuroma. A benign tumor arising from Schwann cells of the vestibular division of the eighth cranial nerve within the internal auditory canal. Also called vestibular schwannomas, these growths are progressively enlarging and commonly lead to progressive hearing loss, headache, ringing in the ear (tinnitus) and balance problems. Treatment options include surgical resection, stereotactic radiosurgery or fractionated radiation therapy. They may be unilateral or bilateral.

Arteriovenous Malformations (AVM). A spectrum of congenital (developmental) blood vessel malformations. An AVM occurs when brain or spinal cord arteries attach directly to veins without the blood passing through the capillary network. AVM's can cause bleeding within the nervous system (a kind of stroke), or progressive neurologic deficits, headaches or seizures. They occur in a variety of brain locations, sizes and shapes. Treatment can consist of observation, surgical resection, embolization or radiosurgery. (See also Spinal Cord Arteriovenous Malformation.)

Astrocytoma. A nervous system tumor that grows from astrocytes (astrocytomas are a type of glial cell, glial cells are the supporting cells of the nervous system). They can occur in children and young adults and sometimes in older people. Astrocytomas can sometimes become large before causing symptoms. A diagnosis is made either after surgical resection or with a guided (stereotactic) biopsy. Treatment can consist of surgical excision, radiation therapy or chemotherapy. Some patients with minimal symptoms may be observed with serial imaging studies.

Ataxia. An abnormality of coordination -- particularly affects walking; gait is typically very unsteady.

Athetosis. Movement disorder indicated by slow, writhing motions of the fingers and hands. Occurs in approximately five percent of people with cerebral palsy. Athetosis was used commonly a few years ago, but now, many of the people who were previously diagnosed as having athetosis are considered to have dystonia. We believe the two disorders are different, in that athetosis affects muscles of the fingers, hands, and around the mouth, causing slow, twisting, writhing motions that are more continuous than dystonic movements.

Atypical Trigeminal Neuralgia. Pain syndrome with characteristics of typical trigeminal neuralgia as well as characteristics of other facial pain syndromes.

Brachial Plexus. The network of spinal nerves (from the lower cervical spine and upper dorsal spine) that innervate the arm, forearm and hand. Located in the neck-shoulder region

Brain Contusion. An injury (bruise) to the brain. This usually occurs in the setting of a head injury but can occur after other kinds of trauma. Contusions sometimes lead to focal neurologic deficit. They can be single or multiple. If the bruise enlarges, a focal hemorrhage can lead to a decline of the patient and require surgical removal.

Brain Metastasis. A tumor, which spreads from one part of the body to another. The most common metastatic tumors in the brain come from lung cancer, breast cancer, skin cancer (melanoma), kidney cancer (renal), or gastrointestinal tract tumors. They can cause seizures, headaches or neurologic deficits. Treatment consists of either tumor irradiation (stereotactic radiosurgery or whole brain radiation therapy), surgical resection, or corticosteroid therapy, alone or in combination.

Brain Tumor. A tumor or neoplasm refers to a "new growth" of cells that already exist in a certain part of the body. Many different tumors can occur in the nervous system. They often cause headaches, seizures or neurological deficits. Tumors can be both benign or malignant. Malignant tumors are referred to as cancers. Tumor treatments can consist of surgical resection or biopsy, radiation approaches or drug treatment approaches (chemotherapy). Other tumors can be treated with modification of the body's own immune system (immunotherapy).

Bypass. Blood vessel procedure where blood is shunted from one blood vessel to another without passing through a diseased segment. This is usually performed if a certain portion of the brains blood supply is significantly compromised. A bypass allows a higher volume of blood to enter the brain in an attempt to prevent a stroke. The most common bypass is an EC-IC (extracranial - intracranial) bypass.

C - D

Carotid Endarterectomy. Procedure where an artery is opened and a portion of atherosclerotic disease (plaque) is removed. Atherosclerosis refers to the "hardening of the arteries" that can occur with advanced age. Patients particularly prone to this are those with risk factors including high blood pressure, smoking, hypercholesterolemia, or family history. Patients who have a carotid endarterectomy usually have significant narrowing of the carotid artery (one of the main arteries supplying the brain with blood). Many patients have symptoms from arterial narrowing such as transient ischemic attacks or stroke.

Carotid Stenosis. Narrowing of the carotid artery caused by atherosclerosis. A plaque forms within the artery leading to it's narrowing (stenosis). The stenosis can be opened by removal of the plaque (endarterectomy) or distention of the plaque (angioplasty).

Carpal Tunnel. Compression of the median nerve at the wrist. This causes numbness in the hand, thumb, and fingers.

Cavernous Malformation. Small tangle of thin walled blood vessels. There is no functioning brain tissue within the malformation. These malformations can bleed causing focal neurologic deficits. In some patients seizures or headaches may occur. Treatment often consists of simple observation, resection, or in some cases radiosurgery.

Cerebral Hemorrhage. (Bleeding inside the head). Bleeding inside the head can result from trauma or rupture of a weak or abnormal blood vessel, such as an aneurysm or arteriovenous malformation. High blood pressure may also rupture blood vessels. Neurosurgical treatment of a cerebral hemorrhage attempts to diagnose and treat the cause of the bleeding, and to safeguard the brain from potential damage caused by the bleeding. Treatment depends on the nature and location of the bleeding. Treatment options include surgical clipping, removal of damaged vessel segments, reinforcement of weakened vessel walls, endovascular occlusion of aneurysmal sacs or arteriovenous feeders, and radiosurgery.

Cerebral Palsy. Spectrum of congenital (from birth) brain injuries or developmental problems. Cerebral palsy may occur after a brain hemorrhage, or in a premature infant. Cerebral palsy often leads to problems with motor control of the arms or legs leading to chronic weakness or spasticity.

Cervical Disc Herniation. Protrusion of one or more of the discs in the neck towards the spinal cord or nerve roots. Cervical disc herniations can cause neck, shoulder or arm pain, or neurologic symptoms such as arm or leg weakness or sensory problems. Treatment often consists of rest or anti-inflammatory medication or in some patients, removal of the offending disc.

Cervical Stenosis. Narrowing of the column for the spinal cord in the neck. Such narrowing usually occurs from overgrowth of disks, ligaments or bony structures that impinge upon the central spinal canal. If the spinal cord or nerve roots are compressed significantly, symptoms can occur. These can lead to problems with arm or leg strength, balance control, sensory symptoms, bowel or bladder dysfunction or pain.

Chiari Malformation. Malformation that may occur with development of the baby or in later life. The malformation consists of a protrusion of the bottom portion of the cerebellum into the upper portion of the spinal canal. This malformation can lead to headaches, arm or leg symptoms, or problems with the nerves that supply the head and neck. When appropriately diagnosed, treatment can consist of surgical decompression of the base of the brain. Other treatments such as spinal fluid diversion (shunting) may also be considered depending on the cause of the malformation.

Chorea. Involuntary abrupt, rapid, brief, and unsustained irregular movement and is sometimes described as "dance-like." Chorea occurs in five percent of people with cerebral palsy.

Coma. State of arousal often after head injury or disease. When a patient is comatose, they are not aware of their general surroundings and do not interact with observers at a normal level.

Cranial Settling. The uppermost bony portion of the neck is called the dens or odontoid process. The skull rests on this process and rotates. Cranial settling occurs when this bone protrudes into the hole in the base of the skull called the foramen magnum. This can be congenital (from birth) or from conditions such as Paget's disease or arthritis. Cranial settling can cause pain in the lower part of the skull and upper neck. It may also cause compression of the spinal cord, which may cause extremity weakness and numbness. This condition can be treated by surgical removal of the dens followed by instrumented cervical fusion.

Cysts. Collection of fluid within a specific cavity. Cysts can form from tumors, after injuries, after bleeding in the brain, or as developmental fluid filled spaces. Spinal cysts are usually benign outpouchings of the covering of spinal nerve roots that are also known as Tarlov's cysts. It is rare that they are symptomatic but can occasionally cause back pain. If symptomatic, they can be treated by surgical resection.

Deafferentation Pain. This pain occurs after loss of normal sensory input to the brain. An example of this is phantom pain where a patient may still feel pain from a foot even though their foot has been amputated. This pain may be difficult to treat. Treatment can consist of medical therapy, behavioral techniques, or electrical stimulation.

Degenerative Disc Disease. The disc material that sits between the bones of the spinal column act like shock absorbers. Over time this fibrous gelatinous matter loses the ability to absorb water and is called degenerative. Having a degenerative disc can cause pain usually in the neck or lower back depending on where in the spine the disc is located. If surgical treatment is considered, surgery includes removal of the degenerated disc and placement of metal instrumentation to fuse the bones together to avoid instability. Surgical options also include less invasive percutaneous (through the skin) needle procedures.

Dural Fistula. Connection between a blood vessel located in the fibrous covering of the brain (dura) to another blood vessel without the blood passing through an intervening capillary network. Dural fistulas can be created by two blood vessels located only within the dura or they can also involve the brain blood vessels. Sometimes dural fistulas can lead to loud noises heard by the patient, a bulging red eye, or headaches. The type of symptoms depends upon the size and location of the specific fistula.

Dystonia. Movement disorder consisting of a tightening and twisting of a limb. The movement is not controlled by the patient. Sometimes dystonias can be painful. They are sometimes seen in patients with cerebral palsy, Parkinson's disease or other neurologic problems.

E - K

Epidural Hematoma. Blood clot located between the bone (cranium) and the dura (fibrous covering of the brain). An epidural hematoma is usually seen after head injury with an associated skull fracture. These hematomas can become large and can compress the underlying brain causing significant neurological problems. Treatment often consists of surgery or if the lesion is small, observation.

Epilepsy. Process where the patient has seizures in association with an underlying disorder. Treatment options consist of one or more medications but with some kinds of epilepsy may include surgery. Epilepsy can occur at all ages.

Essential Tremor. Disabling movement disorder consisting of shaking of one or both hands when the patient uses the hand to do something. They do not have tremor at rest. The cause is unknown. It sometimes runs in families. Treatment can consist of medication or surgery.

Facial Pain. Several types of facial pain are found in patients. One of the most common is trigeminal neuralgia (a sharp, shooting, lancinating pain on one side of the face). Other facial pains can be constant and mixed with one or more different headache syndromes. These can include cluster headache, sphenopalatine neuralgia or pain after facial injury.

Failed Back Syndrome. Patients who have had several back surgeries but continue with troublesome pain or other neurological problems. In some patients, a cause for the continuing pain is not clear. A detailed investigation should be performed to evaluate treatable causes in specific patients.

Fusion. Condition where one or more portions of the spine (vertebra) become attached to one another. A fusion can occur after a spinal fracture. Surgical fusion can be created (using specific hardware) to relieve pain or neurologic deficit caused by abnormal movement of the spine.

Geniculate Neuralgia. Severe deep ear pain. The pain is usually sharp and described as an "ice pick in the ear." However, it can be also described as a duller burning pain and can be accompanied by facial pain.

Glioblastoma. Specific malignant brain tumor. A glioblastoma is a tumor that is part of the astrocytoma cell line. It is considered a grade IV astrocytoma. A glioblastoma is a common brain tumor in adults diagnosed either with stereotactic biopsy or with an open craniotomy and partial tumor resection. Treatment often consists of radiation therapy and in some patients, chemotherapy. These tumors can cause different symptoms based upon their size and brain location.

Glossopharyngeal Neuralgia. Sharp, jabbing, electric, or shock like pain located deep in the throat on one side. It is generally located near the tonsil although the pain may extend deep into the ear. It is usually triggered by swallowing or chewing.

Headache. Discomfort felt in one or more portions of the head. There are many causes of headaches including tension headache, migraine headache, cluster headache, occipital neuralgia or trigeminal neuralgia (specific nerve related pain syndromes). Most headaches are treated with medical therapy.

Hemifacial Spasm. Involuntary twitching of one side of the face. It usually starts around the eye and slowly progresses to involve the lower face. In some patients, it starts around the musculature of the mouth and progresses up the face towards the eye. The muscles in the forehead and neck are usually the last to be affected.

Hydrocephalus. Dilation of the fluid filled chambers of the brain (cerebral ventricles). The cause is usually an obstruction of the normal spinal fluid passage from one fluid chamber to another. Hydrocephalus can occur at birth or develop later on in life from obstructions related to hemorrhage in the brain, meningitis, brain tumors or other causes. Treatment can consist of diverting the spinal fluid into the abdomen or chest (placement of a shunt), or opening up the diversion within the brain (third ventriculostomy). There are other specific procedures that can be used in individual patients. Medication therapy is sometimes used in specific patients. (See also Normal Pressure Hydrocephalus.)

Hyperhidrosis. Commonly noted as sweaty palms and feet. Patients generally note increased sweating in the palms of their hands, feet and possibly also in the trunk.

L - Q

Lumbar Disk Herniation. Protrusion of one of the disks in the lower back. This protrusion can cause pain or neurological symptoms. When the disk protrudes on one of the nerve roots that go down to the leg, either pain, weakness or numbness can develop. If the disk compresses the nerves to the bladder, then bowel or bladder symptoms can develop. Many patients with disk herniation can be treated with rest and return to exercise with physical therapy and anti-inflammatory medications. If severe pain or progressive neurologic symptoms occur, then surgery may be considered.

Lumbar Spinal Stenosis. Narrowing of the spinal canal in the lower back usually due to overgrowth of bone or ligaments of the spinal bones. Such narrowing can cause pressure on the nerves to the leg, which may lead to pain, trouble walking, sensory or bladder symptoms. If symptoms are severe, then decompression of the spine may be necessary.


Meningioma. Tumor that grows from the meninges (dural covering of the brain). These can occur in many different brain locations and can cause symptoms depending on the size of the tumor and the location. Most meningiomas are benign tumors although some can be more aggressive and malignant. Surgical resection can be curable for some patients while others may be best treated with irradiation approaches. In some patients both open surgery and radiation may be required.

Myelocele. Opening in the tissues that surround the spinal cord. It is often congenital (developmental). It is symptomatic. Surgical closure may be necessary. In some patients with open neural tube defects (spina bifida), the opening can proceed all the way through the skin.

Normal Pressure Hydrocephalus. Condition primarily affecting the elderly characterized by poor bladder control, difficulty walking and mild dementia. Condition often mimics Alzheimer's and Parkinson's.

Occipital Neuralgia. Pain syndrome located in the upper neck or back of the head caused by irritation of the occipital nerve. Treatment can consist of medication therapies, or lesioning of the nerve (either by cutting it or by heating it). Appropriate investigations should be performed to rule out other causes of pain from that region.

Osteoporotic Vertebral Compression Fracture. Osteoporosis results in the progressive mineral loss from the bone and changes within the bony architecture, leaving the bones weakened structurally and therefore more subject to fractures. The vertebral bodies, as a major load bearing structure, are particularly prone to fracture. Vertebral compression fractures secondary to osteoporosis usually occur after minor trauma or spontaneously.

Parkinson's Disease. Neurodegenerative disorder caused by the loss of cells that produce a chemical called dopamine. The hallmark of Parkinson's disease is a resting tremor, slowness of movement (bradykinesia), and limb rigidity. Most patients respond to medical therapy but over time the disease can advance. Surgical treatments for Parkinson's disease include brain lesioning (thalamotomy or pallidotomy), deep brain stimulation and new approaches such as experimental transplantation.

Pineal Tumor. The pineal gland is a small structure in the middle of the brain. Primitive tumors can grow in this region often related to developmental body cells (germ cells). Tumors such as germinomas or non-germanomatous germ cell tumors can cause headaches, hydrocephalus or other neurologic symptoms. Treatments can consist of open resection, endoscopic biopsy, stereotactic biopsy, radiation therapy, focused radiation and chemotherapy. Because different tumors can occur in this area, it is important to guide treatment based upon the individual tumor type.

Pituitary Adenoma. A benign tumor. A pituitary gland, responsible for secretion of hormones, can form a tumor. A pituitary adenoma can cause an over secretion of hormones and cause problems such as acromegaly (growth hormone hypersecretion), Cushing's disease (corticosteroid hormone hypersecretion). Prolactinoma refers to a tumor that over secretes prolactin. This often leads to galactorrhea (secretion of milk from breast tissue). If a tumor grows to a large size, it can cause a compression of the optic system leading to visual deficits. Treatments can consist of surgical resection, either through the nose (transsphenoidal surgery) or through the cranium, or radiation approaches.

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Radiculopathy. The irritation of a nerve root at any level of the spine. Radiculopathy can be caused by protrusion of a disk, by arthritis of the spine or by compression from an offending tumor or other process. Radiculopathies can cause pain or neurologic deficits.

Reflex Sympathetic Dystrophy (causalgia)
Pain syndrome often after prior limb injury. The painful limb becomes cold and often associated with increased sweating. Certain medications can help but in some patients, an operation called sympathectomy may be necessary.

Schwannoma. Overgrowth (tumor) of Schwann cells. Schwann cells are responsible for providing the insulation (myelin) for nerves. Schwannomas can occur in the brain, the spine, or the limbs (peripheral nerves). A common brain schwannoma is the vestibular schwannoma (acoustic neuroma), which can lead to hearing loss. Multiple schwannomas can be seen in the setting of neurofibromatosis type 1. Treatment often consists wither of a surgical resection or irradiation.

Seizures. An electrical brain disturbance that leads to a convulsion or other transient neurologic problem. Some seizures may consist only of staring spells. Other can consist of temporary smells or tastes. Other seizures can involve jerking limb movements or numbness. An investigation should be performed to try to identify the cause of the seizures. Medication therapy may be necessary in some patients and occasionally surgery is performed to relieve the seizure focus.

Shunt. A shunt system is used to divert cerebral spinal fluid from the brain to another body compartment. This is usually used to treat hydrocephalus. Shunts can be used to divert fluid from the cerebral ventricles to the abdomen (ventricular peritoneal shunt) or to the chest (ventricular pleural shunt).

Skull Fracture. Fractures of the skull bone (cranium) can occur after mild or severe head injury. A skull fracture may be associated with no symptoms or a mild headache. Other factors can be followed by concussion syndromes or more severe brain injury. An open skull fracture is one in which the overlying skin has also been opened up. A depressed skull fracture is when one of the bony fragments is compressing the brain structures.

Spasticity. Involuntary muscle tightness and stiffness that occurs in about two-thirds of people with cerebral palsy and in many who suffer severe head injuries. The medical definition of dystonia is a velocity-dependent, increased resistance to passive muscle stretch. In other words, when a muscle affected by spasticity is stretched by someone else, it is harder to move the muscle than normal, and the faster one pushes, the harder the muscle is to move.

Spinal Cord Arteriovenous Malformation (SC-AVM). Arteriovenous malformations or AVMs are vascular irregularities that are comprised of arteries and veins that are connected differently than they are in other areas of the body. They are congenital (from birth), rare in the spine, and usually diagnosed with MRI. Spinal cord AVMs can cause symptoms by compressing the spinal cord or by bleeding. They can be treated by observation, a procedure call embolization, and / or surgical resection.

Spinal Fracture. A fracture of any element of the spinal column can lead to pain, neurologic deficit or in some patients, no symptoms at all. Spinal fractures usually occur after some kind of injury. If the spinal bones are unstable, fixation may be required.

Spinal Instability. Certain disorders can lead to excessive movement between one or more spinal bones. An unstable spine can place the nerves or spinal cord at risk for injury. Spinal instability can occur with certain diseases such as rheumatoid arthritis, or after spinal injury. Instability can be managed with an external brace (i.e. a collar), or with surgical fixation. Spinal stenosis refers to a narrowing of the spinal column caused by an excessive overgrowth of the spinal bones, ligaments or other tissues. Spinal stenosis can cause pain or progressive neurologic deficits.

Spinal Tumor. Tumors of the spine can be either benign or malignant. Benign tumors include schwannomas, neurofibromas and meningiomas. Malignant tumors are most commonly caused by cancers that spread from other body areas (i.e. lung, breast, kidney or skin cancer). Tumors of the spinal cord itself can be either benign or malignant. Treatment can consist of radiation surgery or combined approaches depending on the tumor type.

Stroke. Temporary or permanent loss of the blood supply to the brain (thrombotic stroke), or acute bleeding in the brain (hemorrhagic stroke). Strokes cause sudden neurologic deficits that can be mild or severe. When symptoms recover promptly, a patient may have had a transient ischemic attack. When symptoms last for more than 24 hours, a stroke is said to have occurred. Strokes or neurosurgical emergencies in patients should be brought to the hospital as soon as possible. Investigations include brain scans, special blood flow studies, and sometimes tests that show the caliber of blood vessels (angiograms).

Subdural Hematoma. Blood clot that occurs on the surface of the brain and just below the dura (covering of the brain). A subdural hematoma usually occurs from the tear of one of the veins that drain the brain of blood. Subdural hematomas can be either acute (after a recent injury), or chronic (after an old and sometimes unforgotten, even minor or trivial) head injury. Chronic subdural hematomas can be managed with close observation or if the blood clot is sizable, with drainage via burr holes. Acute subdural hematomas usually require an open craniotomy to evacuate the blood clot.

Syringomyelia. This tumor refers to a cavity of fluid that occurs within the spinal cord. The cavity can enlarge slowly and may lead to pain, loss of sensation in the limbs or weakness. They can be found after injury, in relation to tumors or of unknown cause.

T - Z

Tinnitus. Ringing in the ears sometimes caused by compressed blood vessels.

Traumatic Brain Injury. This term refers to the effects on the brain after head injury. Traumatic brain injuries can lead to a spectrum of problems including concussion, contusion (hemorrhage within the brain), or diffuse injuries that cause more severe neurologic deficits.

Trigeminal Neuralgia. Sharp shooting lancinating pain found in the forehead, face or jaw region. The pain is usually on only one side of the face. It can sometimes be seen in the setting of multiple sclerosis. Treatment usually consists of medical therapy (the primary drug is Tegretol ). In patients who are refractory to mediation therapy or have side effects, different surgical approaches such as microvascular decompression, percutaneous rhizotomy (glycerol, radiofrequency or balloon technique) or stereotactic radiosurgery can be performed.

Ulnar Neuropathy. Compression or irritation of the nerve at the elbow. This is sometimes called the "funny bone" and compression of the nerve causes numbness in the little finger and ring finger. Weakness may also be noted.

Venous Malformation. Collection of veins within the brain that look abnormal on a brain scan. The veins however perform their normal function in that they drain blood from the brain back to the heart. They are usually not symptomatic and most patients require no treatment.

Vertebral Compression Fracture. Fracture of the vertebral body. There is usually an acute onset of severe back pain. This back pain, depending on the severity of the fracture, can be mild to severely debilitating. In addition to severe pain, vertebral compression fractures frequently cause malalignment of the spine.
