Neurology_Adams

Neurology_Adams. Testing of Sensory Function The detail with which sensation is tested is determined by the clinical situation. If the patient has no sensory complaints, it is sufficient to test vibration and position sense in the fingers and toes and the perception of pinprick over the extremities, and to determine whether the findings are the same in symmetrical parts of the body. A rough survey of this sort occasionally detects sensory defects of which the patient was unaware. More thorough testing is in order if the patient has complaints referable to the sensory system or if one finds localized atrophy or weakness, ataxia, trophic changes of joints, or painless ulcers.


Neurology_Adams

Neurology_Adams. A few other general rules are useful. It is easier for a patient to perceive the boundary of an abnormal area of sensation if the examiner proceeds from an area of reduced sensation toward the normal area. One should not press the sensory examination in the presence of fatigue, for an inattentive patient is a poor witness. Also, the examiner must avoid suggesting symptoms to the patient. After explaining in the simplest terms what is required, the examiner interposes as few questions and remarks as possible. Patients should generally not be asked, “Do you feel that?” each time they are touched; they are simply told to say “yes” or “sharp” every time they are touched or feel pain. Repetitive pinpricks within a small area of skin should be avoided, as this will make inapparent a subtle hypalgesia, because of the phenomenon of temporal summation as discussed earlier. In patients who may be overinterpreting slight changes in pinprick, differentiating between warm and cold is often more


Neurology_Adams

Neurology_Adams. because of the phenomenon of temporal summation as discussed earlier. In patients who may be overinterpreting slight changes in pinprick, differentiating between warm and cold is often more informative than differentiating between “sharp” and “dull.” The patient should not directly observe the part under examination. A cooperative patient may, if asked to use a pin or his fingertips, outline an analgesic or anesthetic area or determine whether there is a graduated loss of sensation in the distal parts of a leg or arm. Finally, the findings of the sensory examination should be accurately recorded in narrative or on a chart by shading affected regions on a preprinted figure of the body or a sketch of a hand, foot, face, or limb.


Neurology_Adams

Neurology_Adams. Described below are the usual bedside methods of testing sensory function. These tests are sufficient for most clinical purposes. For clinical investigation and research into the physiology of pain, which require the detection of threshold values and quantification of sensory impairment, a wide range of instruments are available. Their use has been described by Dyck and colleagues. Testing of Tactile Sensation


Neurology_Adams

Neurology_Adams. Testing of Tactile Sensation This is usually done with a wisp of cotton, a tissue, or light touch of a finger. The patient is first acquainted with the stimulus by applying it to a normal part of the body. Then, with eyes closed, he is asked to indicate if the sensation feels “natural” or to say “yes” each time various other parts are touched. A patient with factitious sensory loss may say “no” in response to a tactile stimulus. Cornified areas of skin, such as the soles and palms, will require a heavier stimulus than other areas and the hair-clad parts a lighter one because of the numerous nerve endings around the follicles. Patients will be more sensitive to a moving stimulus of any kind than to a stationary one. The deft application of the examiner’s or the patient’s roving fingertips is a useful refinement and aids in demarcating an area of tactile loss, as Trotter and Davies originally showed.


Neurology_Adams

Neurology_Adams. More precise testing is possible by using a von Frey hair. By this method, a stimulus of constant strength can be applied and the threshold for tactile sensation determined by measuring the force required to bend a hair of known length. Spurious areas of hypesthesia or hyperesthesia may arise when a series of contactual stimuli lead to a decrement of sensation, either through adaptation of the end organ or because the initial sensation outlasts the stimulus and seems to spread. Testing of Pain Perception


Neurology_Adams

Neurology_Adams. Testing of Pain Perception This is most efficiently assessed by pinprick, although it may be evoked by a variety of noxious stimuli. Patients must understand that they are to report the feeling of sharpness, not simply the feeling of contact or pressure of the pinpoint. If pinpricks are applied rapidly in one area, their effect may be summated and a heightened perception of pain may result; therefore, they should be delivered about one per second and not over the same spot. Small differences in intensity can be discounted. An effective approach is to ask the patient to compare the pin sensation in two areas on a scale of 1 to 10; a report of “8 or 9” as compared to “10” is usually insignificant.


Neurology_Adams

Neurology_Adams. It is almost impossible, using an ordinary pin, to apply each stimulus with equal intensity. A pinwheel (Wartenberg wheel) is sometimes more effective because it allows the application of a more constant pressure, but risk of transmission of blood-borne infection from patient to patient has made this method outdated. For research purposes, this difficulty can be overcome by the use of an algesimeter, which delivers stimuli of constant intensity or with devices using lasers to produce graduated spots of heat intensity on the skin. Quantification of small-fiber sensation can be better assessed in the clinical laboratory by the use of thermal stimuli delivered by a computerized device as described below.


Neurology_Adams

Neurology_Adams. If an area of diminished or absent touch or pain sensation is encountered, its boundaries should be demarcated to determine whether it has a segmental or peripheral nerve distribution, or is lost below a certain level on the trunk. As mentioned, such areas are best delineated by proceeding from the region of impaired sensation toward the normal. The changes may be confirmed by dragging a pin lightly over the parts in question. Areas of reduced pinprick sensation can be corroborated by the thermal sense examination, as below. Testing of Thermal Sense


Neurology_Adams

Neurology_Adams. Testing of Thermal Sense A quick but rough way to assess thermal loss (or to corroborate a previously found zone of hypalgesia) is to warm one side of a tuning fork by rubbing it briskly against the palm and apply its alternate sides to the patient’s skin and asking the patient which side is colder (or warmer). One advantage of this mode of testing is that it offers the patient a binary choice of “warm” or “cold” response. This suffices for most bedside examinations.


Neurology_Adams

Neurology_Adams. If more careful examination is required, the skin should first be exposed to room air for a brief time. The test objects should be large, ideally two stoppered test tubes containing hot (45°C/113°F) and cold (20°C/68°F) tap water. The use of warm and cool water from a tap is adequate and more practical for this purpose. The side of each tube is applied successively to the skin for a few seconds and the patient is asked to report whether the flask feels “less hot” or “less cold” in comparison to a normal part. It is of interest that patients are able to recognize a difference of 1°C (1.8°F) or even less in the range of 28°C (82.4°F) to 32°C (89.6°F); in the warm range, differences between 35°C (95°F) and 40°C (104°F) can be recognized, and in the cold range, between 10°C (50°F) and 20°C (68°F). If the temperature of the test object is below 10°C (50°F) or above 50°C (122°F), sensations of cold or heat become confused with pain. This technique has been largely supplanted by commercial


Neurology_Adams

Neurology_Adams. If the temperature of the test object is below 10°C (50°F) or above 50°C (122°F), sensations of cold or heat become confused with pain. This technique has been largely supplanted by commercial devices that can present a series of slightly differing thermal stimuli in sequence to a probe placed on the finger or toe. Special algorithms are used to vary the order and magnitude of temperature change and to determine whether the patient’s reports are consistent and valid. The results are reported in the form of a “just noticeable difference” (JND) between temperatures or intensities of pain.


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Neurology_Adams. Testing of Deep-Pressure Pain One can estimate the perception of this modality simply by pressing deeply on the tendons, muscles, or bony prominences. Pain can be elicited by heavy pressure even when superficial sensation is diminished; conversely, in some diseases, such as tabetic neurosyphilis, loss of deep-pressure pain may be more striking than loss of superficial pain. This uncomfortable examination should be omitted in routine neurological cases. Deep pain, strictly speaking, is a proprioceptive sense because it is below the skin surface, but the sensory pathways are spinothalamic and therefore more allied with pain. Testing of Proprioceptive Sense


Neurology_Adams

Neurology_Adams. Testing of Proprioceptive Sense Awareness of the position and movements of our limbs, fingers, and toes is derived from receptors in the muscles, tendons (Golgi tendon organs, according to Roland and Ladegaard-Pederson), and joints and is probably facilitated by the activation of skin receptors (Moberg). The two modalities comprising proprioception, that is, sense of movement and of position, are usually impaired in parallel, although clinical situations do arise in which perception of the position of a limb or digits is lost while that of passive and active movement (kinesthesia) of these parts is retained. The opposite occurs but is infrequent. Moreover, it is our impression that within the limits of what is done in bedside examination, patients more easily perceive joint movement (arthresthesia) than static joint position or posture (statognosis).


Neurology_Adams

Neurology_Adams. Perception of passive movement is first tested in the fingers and toes as the defect, when present, is reflected maximally in these parts. It is important to grasp the digit at the sides, perpendicular to the plane of movement; otherwise the pressure applied by the examiner may allow the patient to identify the direction of movement. This applies as well to testing of the more proximal segments of the limb. The patient may be instructed to first report the perception of joint movement and then to indicate each movement as being “up” or “down.” It is useful to demonstrate the test with a large and easily identified movement, but once the idea is clear to the patient, the smallest detectable changes should be determined. The part being tested should be moved rapidly. Normally, a very slight degree of movement is appreciated in the digits (as little as 1 or 2 degrees of an arc). The test should be repeated enough times to account for the possibility of chance guessing.


Neurology_Adams

Neurology_Adams. Defective perception of passive movement is judged by comparison with a normal limb or, if perception is bilaterally defective, on the basis of what the examiner has learned through experience to be normal. Slight impairment may be disclosed by a slowness of response or, if the digit is displaced very slowly, by an unawareness or uncertainty that movement has occurred; or, after the digit has been displaced in the same direction several times, the patient may misjudge the first movement in the opposite direction; or, after the examiner has moved the digit, the patient may make a number of small voluntary movements of the toe in an apparent attempt to determine its position or the direction of the movement. Inattentiveness will also cause some of these errors. If joint position sense is impaired at a distal site, the next proximal joint may be tested. The lack of position sense in the legs can also be demonstrated by displacing the limb from its original position and having the


Neurology_Adams

Neurology_Adams. is impaired at a distal site, the next proximal joint may be tested. The lack of position sense in the legs can also be demonstrated by displacing the limb from its original position and having the patient, with eyes closed, place the other leg in the same position or point to the great toe. The same is true for the arm and hand.


Neurology_Adams

Neurology_Adams. If proprioception is abnormal in axial structures, the patient will be unable to maintain his balance with feet together and eyes closed (Romberg sign). This test is often interpreted imprecisely. In the Romberg position, even a normal person whose eyes are closed will sway slightly, and the patient who lacks balance because of cerebellar ataxia or some other motor disorder will sway considerably more if his visual cues are removed. Only a marked discrepancy in balance with eyes open and with eyes closed qualifies as a Romberg sign. The most certain indication of abnormality is the need to step to the side or backward to avoid falling. Mild degrees of unsteadiness in an anxious or suggestible patient may be overcome by diverting his attention, for example, by having him touch the index finger of each hand alternately to his nose while standing with eyes closed or by following the examiner’s finger with his eyes. Patients with authentic proprioceptive problems will sway when there gaze


Neurology_Adams

Neurology_Adams. of each hand alternately to his nose while standing with eyes closed or by following the examiner’s finger with his eyes. Patients with authentic proprioceptive problems will sway when there gaze is diverted from the ground and then become more unsteady when the eyes are closed. Patients with factitious unsteadiness usually will remain stable when they follow the examiner’s fingers or look alternately at the ceiling and then at a distant object but then appear to be very unsteady when the eyes are closed. It is important to remember that any defect in proprioception (e.g., peripheral neuropathy, myelopathy or vestibulopathy) will lead to a Romberg sign even though the sign, described by Moritz Romberg, was meant to diagnose tabes dorsalis.


Neurology_Adams

Neurology_Adams. Abnormalities of position sense may also be disclosed when the patient has his arms outstretched and eyes closed. The affected arm will wander from its original position; if the patient’s fingers are spread apart, they may undergo a series of changing postures (“piano-playing” movements, or pseudoathetosis); in attempting to touch the tip of his nose with the index finger, the patient may miss the target repeatedly, but the performance is corrected when the eyes are open. Testing of Vibratory Sense


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Neurology_Adams. Testing of Vibratory Sense This is a composite sensation comprising touch and rapid alterations of deep-pressure sense but for clinical work, it may be considered a useful single modality. The cutaneous structure capable of registering stimuli of frequencies that are used for clinical testing is probably the pacinian corpuscle. The conduction of vibratory sense depends on large sensory fibers that ascend mainly in the dorsal columns of the cord. Consequently, it is rarely affected by lesions of single nerves but will be disturbed in patients with disease of multiple peripheral nerves, dorsal columns, medial lemniscus, and thalamus. Vibration and position sense are usually impaired in similar conditions, although one of them (most often vibration sense) may be affected disproportionately. With advancing age, vibration is the sensation most commonly diminished, especially at the toes and ankles (see further on).


Neurology_Adams

Neurology_Adams. Vibration sense is tested by placing a tuning fork with a low frequency and long duration of vibration (generally 128 Hz) over the bony prominences, making sure that the patient responds to the vibration, not simply to the pressure of the fork, and that he is not trying to listen to the generated sound. Quantitative tuning forks with a 0 to 8 scale are available but it is sufficient for clinical purposes to compare the point tested with a normal part of the patient or the examiner. The examiner may detect the vibration after it ceases for the patient by holding a finger under the distal interphalangeal joint, the handle of the tuning fork being placed on the dorsal aspect of the joint. Or the tuning fork is allowed to run down until the moment that vibration is no longer perceived, at which point the fork is transferred quickly to the corresponding part of the examiner and the time to extinction is noted. There is a small degree of accommodation to the vibration stimulus, so that


Neurology_Adams

Neurology_Adams. which point the fork is transferred quickly to the corresponding part of the examiner and the time to extinction is noted. There is a small degree of accommodation to the vibration stimulus, so that slight asymmetries detected by rapid shifting from a body part on one side to the other or to the examiner should be interpreted accordingly. The perception of vibration at the patella after it has disappeared at the ankle or at the anterior iliac spine after it has disappeared at the knee is indicative of a length-dependent peripheral neuropathy. The approximate level of pinprick loss from a spinal cord lesion can be corroborated by testing vibratory sensation over the iliac crests and successive dorsal vertebral spines. As with thermal and pain testing, there are mechanical devices that are able to quantitate vibration sense.


Neurology_Adams

Neurology_Adams. Testing of Discriminative (Parietal Lobe Cortical) Sensation Damage to the parietal lobe sensory cortex or to the thalamocortical projections results in a particular type of disturbance—namely, an inability to make sensory discriminations and to integrate spatial and temporal sensory information (see further under “Sensory Loss Caused by Lesions of the Parietal Lobe” and Chap. 21). Lesions in these structures usually disturb complex sensory perception but leave the primary modalities (touch, pain, temperature, and vibration sense) relatively less affected. The integrity of discriminative sensory functions can be assessed only if it is first established that the primary sensory modalities on which they depend (mainly touch) are largely normal. If a cerebral lesion is suspected, discriminative function can be tested further in the following ways.


Neurology_Adams

Neurology_Adams. The ability to distinguish two points from one is tested by using a compass or similar device, the points of which should be blunt and applied simultaneously and painlessly. The distance at which such stimuli can be recognized as a distinct pair varies but is roughly 1 mm at the tip of the tongue, 2 to 3 mm on the lips, 3 to 5 mm at the fingertips, 8 to 15 mm on the palm, 20 to 30 mm on the dorsal hands and feet, and 4 to 7 cm on the trunk. It is characteristic of the patient with a lesion of the sensory cortex to mistake two points for one, although occasionally the opposite occurs.


Neurology_Adams

Neurology_Adams. Localization of cutaneous tactile or painful stimuli is tested by touching various points on the body and asking the patient to place the tip of his index finger on the point stimulated or on the corresponding point of the examiner’s limb. Recognition of numbers or letters traced on the skin (these should be larger than 4 cm on the palm) with a pencil or similar object or the direction of a line drawn across the skin also depends on localization of tactile stimuli but the two may be dissociated. Normally, traced numbers as small as 1 cm can be detected on the pulp of the finger if drawn with a pencil. These are also useful tests of posterior column function. Appreciation of Texture, Size, and Shape


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Neurology_Adams. Appreciation of texture depends mainly on cutaneous impressions, but recognition of the shapes and sizes of objects is based on sensory experience from deeper receptors as well. Inability to recognize shape and form is frequently a manifestation of cortical disease, but a similar clinical defect will occur if tracts that transmit proprioceptive and tactile sensation are interrupted by lesions of the spinal cord and brainstem (and, of course, of the peripheral nerves). This type of sensory defect is called stereoanesthesia (see further on, under “Posterior [Dorsal] Column Syndrome”) and is distinguished from astereognosis, which connotes an inability to identify an object by palpation, even though the primary sense data (touch, pain, temperature, and vibration) are intact. In practice, pure astereognosis is rarely encountered, and the term is employed when the impairment of superficial and vibratory sensation in the hands seems to be of insufficient severity to account for the defect


Neurology_Adams

Neurology_Adams. astereognosis is rarely encountered, and the term is employed when the impairment of superficial and vibratory sensation in the hands seems to be of insufficient severity to account for the defect in tactile object identification. Defined in this way, astereognosis is either rightor left-sided and, with the qualifications mentioned below, is the product of a lesion in the opposite hemisphere, involving the sensory cortex, particularly S2 or the thalamoparietal projections.


Neurology_Adams

Neurology_Adams. The traditional doctrine that somatic sensation is represented only in the contralateral parietal lobe is not absolute. Beginning with the report by Oppenheim in 1906, there have been patients who showed bilateral astereognosis or loss of tactile sensation as a result of an apparently unilateral cerebral lesion. These observations were corroborated by Semmes and colleagues, who tested a large series of patients with traumatic lesions involving either the right or left cerebral hemisphere. They found that the impairment of sensation (particularly discriminative sensation) following right-and left-sided lesions was not strictly comparable; the left hand as well as the right tended to be impaired by injury to the left sensorimotor region, whereas only the left hand tended to be affected by injury to the right sensorimotor region. These observations, with minor qualifications, were also confirmed by Carmon and by Corkin and associates (1965), who investigated the sensory effects of


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Neurology_Adams. by injury to the right sensorimotor region. These observations, with minor qualifications, were also confirmed by Carmon and by Corkin and associates (1965), who investigated the sensory effects of cortical excisions in patients with focal epilepsy. Thus it appears that certain somatosensory functions in some patients are mediated not only by the contralateral hemisphere but also by the ipsilateral one, although the contribution of the former is undoubtedly the more significant.


Neurology_Adams

Neurology_Adams. This concept of left hemispheric dominance in respect to tactile perception has also been questioned by Carmon and Benton, who found that the right hemisphere is particularly important in perceiving the direction of tactile stimuli. Also, Corkin and associates observed that patients with lesions of the right hemisphere show a consistently greater failure of tactile-maze learning than those with left-sided lesions, pointing to a relative dominance of the right hemisphere in the mediation of tactile performance involving a spatial component. Certainly the related phenomenon of sensory inattention or extinction is more prominent with lesions of the right as opposed to the left parietal lobe and is most informative if the primary and secondary sensory cortical areas are spared. These matters are considered further on in this chapter and in Chap. 21.


Neurology_Adams

Neurology_Adams. Finally, there is a distinction between astereognosis and tactile agnosia. Some authors (e.g., Caselli) have defined tactile agnosia as a strictly unilateral disorder, right or left, in which the impairment of tactile object recognition is unencumbered by a disturbance of the primary sensory modalities. Such a disorder would be designated by others as a form of astereognosis (see above). In our view, tactile agnosia is a disturbance in which a one-sided lesion lying posterior to the postcentral gyrus of the dominant parietal lobe results in an inability to recognize an object by touch in both hands. According to this view, tactile agnosia is a disorder of apperception of stimuli and of translating them into symbols, akin to the defect in naming parts of the body, visualizing a plan or a route, or understanding the meaning of the printed or spoken word (visual or auditory verbal agnosia). These and other agnosias are discussed in Chap. 21. Interruption of a Single Peripheral Nerve


Neurology_Adams

Neurology_Adams. Interruption of a Single Peripheral Nerve The region of sensory loss after complete transection of a sensory or mixed nerve corresponds to the distribution of the cutaneous fibers that derive from the nerve. This is the basis of the sensory map shown in Fig. 8-1. This can be contrasted with the patterns of sensory loss due to section of nerve roots, depicted by the dermatomal map (see Fig. 8-3), which is highly predictable but has less distinctive boundaries. Of course, section of a mixed nerve weakens the muscles that it innervates and the full syndrome can be identified by the combination of these features.


Neurology_Adams

Neurology_Adams. If a large area of skin is involved, the sensory defect characteristically consists of a central portion in which all forms of cutaneous sensation are lost, surrounded by a zone of partial loss, which becomes less marked as one proceeds from the center to the periphery. Following experimental cutting of a nerve, the area of cutaneous sensory loss is less than its anatomic distribution because of overlap from adjacent nerves. After a period of time, the area of tactile loss is greater than that for analgesia because collateral growth from adjacent fibers is more rapid for small free nerve ending subserving pain than it is for fibers for touch. Moreover, there is greater overlap of adjacent pain sensory fields. Along the margin of the hypesthetic zone, the skin becomes excessively sensitive (hyperesthetic); light contact may be felt as smarting and mildly painful. According to Weddell, the dysesthesias are attributable to the greater sensitivity of collateral regenerating fibers that


Neurology_Adams

Neurology_Adams. (hyperesthetic); light contact may be felt as smarting and mildly painful. According to Weddell, the dysesthesias are attributable to the greater sensitivity of collateral regenerating fibers that have made their way from surrounding healthy pain fibers into the denervated region. With section of purely cutaneous nerves, perceptions of deep pressure and passive movement remain intact because these modalities are mediated by nerve fibers from subcutaneous structures and joints.


Neurology_Adams

Neurology_Adams. Particular types of lesions have differing effects on sensory nerve fibers. Compression of a nerve ablates mainly the function of large touch and pressure fibers and leaves the function of small pain, thermal, and autonomic fibers intact; lidocaine has the opposite effect. The effects of sustained pressure on a nerve for as long as 30 min, produces paresthesiae within a few minutes, followed by sensory loss—first of touch and vibration, then of cold, fast pain, heat, and slow pain, in that order and spreading centripetally. Physiologic studies have confirmed the theory of Lewis and colleagues that compression blocks the function of nerve fibers in order of their size. Release of the pressure results in postcompression paresthesia, which has been shown to arise from spontaneous activity that is generated along the myelinated nerve fibers from ectopic sites at a distance from the compression. Within seconds of releasing the pressure, there is an array of tingling, stinging, cramp-like


Neurology_Adams

Neurology_Adams. is generated along the myelinated nerve fibers from ectopic sites at a distance from the compression. Within seconds of releasing the pressure, there is an array of tingling, stinging, cramp-like sensations that reach maximum intensity in 90 to 120 s and slowly fade (Lewis et al). Sensory function is recovered in an order inverse to that in which it was lost. Similar spontaneous and ectopic discharges probably explain the paresthetic symptoms early in the acute demyelinating neuropathies, even before the appearance of sensory loss or numbness. It is worth emphasizing that these features of compression are not because of nerve ischemia, as commonly stated; instead, they result from reversible physiologic changes in the myelin and underlying axon.


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Neurology_Adams. Certain maneuvers for the provocation of positive sensory phenomena—e.g., the Tinel sign of tingling upon percussion of a regenerating peripheral nerve and the Phalen sign of paresthesia in the territory of the median nerve on wrist flexion—typify the susceptibility of a damaged nerve to pressure. In the case of a severed nerve, regeneration from the proximal end begins within days. The thin, regenerating sprouts are unusually sensitive to mechanical stimulation, which produces tingling, or the Tinel sign. Diffuse Involvement of Nerves (Polyneuropathy) (See Table 8-3)


Neurology_Adams

Neurology_Adams. As most polyneuropathies affect mixed nerves, the sensory changes are accompanied by varying degrees of motor and reflex loss. Usually the sensory impairment is roughly symmetrical and the predominant symptoms are numbness and paresthesias. Because in most types of polyneuropathy the longest and largest axons are the most affected (“length dependent,” axonal neuropathy), sensory loss begins in, and is most severe over the feet and legs and, if the upper limbs are affected, over the hands. As the polyneuropathy progresses the margin of sensory loss “ascends,” meaning it moves proximally on the limbs. The term glove-and-stocking, employed to describe the distribution of sensory loss of polyneuropathy, draws attention to the predominantly distal pattern of involvement but does not convey that the change from normal to impaired sensation is characteristically gradual. (In psychogenic sensory loss, by contrast, the border between normal and absent sensation is usually sharply defined.) The


Neurology_Adams

Neurology_Adams. the change from normal to impaired sensation is characteristically gradual. (In psychogenic sensory loss, by contrast, the border between normal and absent sensation is usually sharply defined.) The abdomen, thorax, and face are spared in polyneuropathy except in the most severe cases, in which sensory changes may be found over the anterior thoracoabdominal escutcheon and around the mouth.


Neurology_Adams

Neurology_Adams. In processes that affect axons, numbness and loss of pain and thermal sensations are the main features. When the neuropathy is primarily demyelinating rather than axonal, paresthesia may be the earliest feature. The sensory loss of polyneuropathy usually involves all modalities of sensation, and—although it is difficult to compare the degrees of impairment of pain, touch, temperature, vibration, and position senses—one modality may be impaired disproportionately to the others. This clinical feature is explained by the fact that particular diseases of the peripheral nerves selectively damage sensory fibers of different size. For example, degeneration or demyelination of the large fibers that subserve kinesthetic sense causes a loss of vibratory and position sense and relative sparing of pain, temperature, and, to some degree, tactile perception. When extreme, such a polyneuropathy results in pseudoathetoid movements of the outstretched fingers or toes, manifestations of searching


Neurology_Adams

Neurology_Adams. of pain, temperature, and, to some degree, tactile perception. When extreme, such a polyneuropathy results in pseudoathetoid movements of the outstretched fingers or toes, manifestations of searching movements of the limbs; it may also result in a sensory ataxia because of dysfunction of the large-diameter nerves destined for the spinocerebellar tracts.


Neurology_Adams

Neurology_Adams. By contrast, involvement of the small-caliber, thinly myelinated and unmyelinated axons affects pain, temperature, and autonomic function, with preservation of proprioceptive, vibration, and tactile sense—producing a syndrome of “pseudosyringomyelia,” simulating the dissociated pain from tactile sensory loss that is seen in this disease of the spinal cord (see further on, under “Sensory Spinal Cord Syndromes”). Prolonged analgesia may lead to trophic ulcers and Charcot joints. These patterns of sensory loss, as well as those produced by the plexopathies and mononeuritis multiplex, are discussed further in Chap. 43. Involvement of Nerve Roots (Radiculopathy and Polyradiculopathy) (Figs. 8-1, 8-3, and Table 8-3)


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Neurology_Adams. The surface innervation of the sensory nerve roots serves as one of the most useful and dependable guides to localization in neurology and the main dermatomes are known to all physicians. As already noted, there is considerable overlap from adjacent roots so that division of a single sensory root does not produce complete loss of sensation in any area of skin. However, compression of a single sensory cervical or lumbar root (e.g., by a herniated intervertebral disc) can cause a segmental impairment of cutaneous sensation. When two or more contiguous roots have been completely divided, there may be a zone of sensory loss, which is surrounded by a narrow zone in which there is a raised threshold accompanied by excessive sensitivity (hyperpathia). For reasons not altogether clear, partial sensory loss from root lesions is easier to demonstrate by the use of a painful stimulus than by a tactile or pressure stimulus.


Neurology_Adams

Neurology_Adams. Disease of the nerve roots frequently gives rise to “shooting” (lancinating) pains and burning sensations that project down the course of their derivative sensory nerves. The common examples are sciatica, from lower lumbar or upper sacral root compression, and sharp pain radiating from the shoulder and down the upper arm, from cervical root compression.


Neurology_Adams

Neurology_Adams. When multiple roots are affected (polyradiculopathy) by an infiltrative, inflammatory, or compressive process, the syndrome is more complex and must be differentiated from polyneuropathy. The distinguishing features of a polyradiculopathy, typically aside from pain, are asymmetrical muscle weakness that involves proximal and distal parts differentially in each limb and a pattern of sensory loss that is consistent with the distribution of several roots, not necessarily contiguous ones. Viewed differently, the distribution of sensory and motor deficits defies the pattern expected of multiple single peripheral nerves and fails to display the length-dependent pattern of a generalized polyneuropathy. Further details can be found in Chap. 43. Involvement of Dorsal Root Ganglia (Sensory Neuronopathy, Ganglionopathy) (See Table 8-3)


Neurology_Adams

Neurology_Adams. Widespread disease of the sensory (dorsal root) ganglia produces many of the same sensory defects as disease of the posterior nerve roots (see below under “Tabetic Syndrome”), but it has greater hypesthesia and hypalgesia of proximal areas of the body such as the face, oral mucosa, scalp, trunk, and genitalia. Proprioception is diminished or lost in distal and, to a variable extent, proximal body parts, and occurs in parallel with ataxic movements, often quite severe, and with pseudoathetosis. These latter features, perhaps more than any others, are characteristic of a ganglionopathy and may render the patient incapable of using the limbs, despite preserved strength. Tendon reflexes are lost. Sometimes there are additional features of dysautonomia, but strength is entirely spared. Recognition of this unusual pattern of pansensory loss is of considerable diagnostic importance, because it raises for consideration a number of underlying diseases that might otherwise be overlooked; these


Neurology_Adams

Neurology_Adams. of this unusual pattern of pansensory loss is of considerable diagnostic importance, because it raises for consideration a number of underlying diseases that might otherwise be overlooked; these diseases are discussed in Chap. 43. The main causes of this syndrome are paraneoplastic, connective tissue disease, particularly Sjögren syndrome, toxic exposure, and idiopathic inflammation.


Neurology_Adams

Neurology_Adams. Tabetic Syndrome (See Table 8-3 and Fig. 8-7) The tabetic syndrome, characterized by tabes dorsalis, consists of sensory ataxia and severe imbalance with a positive Romberg test as a result of proprioceptive loss. In its most extreme form the feet slap and stomp as they meet the ground. It can be considered a subtype of polyradiculopathy or ganglionopathy but it also classified with diseases of the spinal cord because the same disorder derives from diseases that affect the posterior columns. Furthermore, the processes that affect that root or ganglion lead to wallerian degeneration of posterior columns. Although inextricably allied in the past with neurosyphilis, it occurs in diabetes mellitus and other diseases that involve the posterior roots or dorsal root ganglia, such as paraneoplastic ganglionopathies.


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Neurology_Adams. In addition to the sensory ataxia, numbness or paresthesia and “lightning” or lancinating pains are frequent complaints; areflexia, and hypotonia without significant muscle weakness is found. The sensory loss may involve only vibration and position senses in the lower extremities but loss or impairment of superficial or deep pain sense or of touch may appear in severe cases. Loss of deep tendon reflexes distinguishes the sensory root syndrome from a lesion in the posterior columns. The feet and legs are most affected in tabes, much less often the arms and trunk. The Romberg sign is prominent, as noted earlier. In extreme cases, atonicity of the bladder with retention of urine and trophic joint changes (Charcot joints) and crises of abdominal (“gastric”) pains are associated.


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Neurology_Adams. Cases of congenital absence of all cutaneous sensation resulting from the lack of development of small sensory ganglion cells may produce the tabetic syndrome; this is discussed in Chap. 7. A similar but partial defect may be found in the Riley-Day syndrome (Chap. 25). There are also forms of hereditary polyneuropathy that cause universal insensitivity. (See Also Chap. 42.) Complete Spinal Sensory Syndrome (Fig. 8-7)


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Neurology_Adams. (See Also Chap. 42.) Complete Spinal Sensory Syndrome (Fig. 8-7) With a complete transverse disruption of the spinal cord, the most striking features are paralysis and loss of all forms of sensation below a level that corresponds to the lesion. There may be a narrow zone of hyperesthesia at the upper margin of the anesthetic zone. Loss of pain, temperature, and touch sensation may begin one or two segments below the level of the lesion; vibratory and position senses have less-discrete levels but they can be detected by careful examination. The sensory (and motor) loss in spinal cord lesions that involve both gray and white matter is expressed in patterns corresponding to bodily segments or dermatomes. These are shown in Figs. 8-3 and 8-4 and are most obvious on the trunk, where each intercostal nerve has a transverse distribution.


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Neurology_Adams. Also, it is important to remember that during the subacute evolution of a transverse spinal cord lesion, there may be a discrepancy between the level of the lesion and that of the sensory loss, the latter ascending as the lesion progresses. This can be understood if one conceives of a lesion as evolving from the periphery to the center of the cord, affecting first the outermost fibers carrying pain and temperature sensation from the legs. Conversely, a lesion advancing from the center of the cord will affect these modalities in the reverse order, in a pattern of sacral sparing, meaning that sensation is preserved over the buttocks and anal region but is absent over the trunk and legs. Hemisection of the Spinal Cord (Brown-Séquard Syndrome)


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Neurology_Adams. Hemisection of the Spinal Cord (Brown-Séquard Syndrome) Disease may be confined to or predominate on one side of the spinal cord; pain and thermal sensation are affected on the opposite side of the body, and proprioceptive sensation is affected on the same side as the lesion. This pattern is the result of loss of pain and thermal senses corresponding to the opposite spinothalamic tract and loss of touch and proprioceptive sense corresponding to the ipsilateral posterior column. Although rarely present in its entirety, a partial Brown-Séquard syndrome is common in practice. The loss of pain and temperature sensation begins one or two segments below the lesion. An associated spastic motor paralysis on the side of the lesion completes the syndrome (see Fig. 8-7). Touch sensation is less affected, as the fibers from one side of the body are distributed in tracts (posterior columns, anterior and lateral spinothalamic) on both sides of the cord.


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Neurology_Adams. Syringomyelic Syndrome (Lesion of the Central Gray Matter)


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Neurology_Adams. Because spinothalamic fibers conducting pain and temperature sensation cross the cord in the anterior commissure, a lesion of considerable vertical extent in this location characteristically abolishes these modalities on both sides over several segments (dermatomes) but spares tactile sensation because the posterior columns are unaffected (see Fig. 8-7). This is termed dissociated sensory loss. Because the lesion frequently involves other parts of the gray matter, varying degrees of segmental amyotrophy and reflex loss are usually present as well. If the lesion has extended to the white matter, corticospinal, spinothalamic, and posterior column signs will be conjoined. The most common cause of such a lesion in the cervical region is the centrally situated developmental syringomyelia; less common are intramedullary tumor, trauma, and hemorrhage. A pseudosyringomyelic syndrome was mentioned earlier in relation to small-fiber neuropathies that simulate syringomyelia.


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Neurology_Adams. Paresthesias in the form of tingling and pins-and-needles sensations or girdleand band-like sensations are common complaints with posterior column disease. In some cases there may be the additional feature of a diffuse, burning, unpleasant sensation in response to pinprick. Loss of vibratory and position sense occurs below the level of the lesion, but the perception of pain and temperature is affected relatively little or not at all. Because posterior column lesions are caused by the interruption of central projections of the dorsal root ganglia cells, they may be difficult to distinguish from a process that affects large fibers in sensory roots (tabetic syndrome discussed above); however, the tendon reflexes are spared in the former and eliminated in tabes. In some diseases that involve the dorsal columns, vibratory sensation may be involved predominantly, whereas in others, position sense is more affected.


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Neurology_Adams. With posterior column lesions, only a few of which have been verified by postmortem examinations, touch sensation is not lost, or it recovers after an acute lesion, but the patient is deprived of knowledge of movement and position of parts of the body below the lesion. Nathan and colleagues confirmed that lesions of the posterior columns cause only slight defects in touch and pressure sensation. However, a combined lesion in both posterior columns and spinothalamic tracts causes a total loss of tactile and pressure sensibility below the lesion. If the posterior column lesion is in the cervical region, there is clumsiness in the palpation of objects and an inability to recognize the qualities of objects by touch (agraphesthesia), even though touch-pressure sensation is relatively intact. There may be unusual disturbances of touch and pressure, manifesting as lability of threshold, persistence of sensation after removal of the stimulus, and sometimes tactile and postural hallucinations.


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Neurology_Adams. The loss of sensory functions that follows a posterior column lesion—such as impaired two-point discrimination; figure writing; detection of size, shape, weight, and texture of objects; and ability to detect the direction and speed of a moving stimulus on the skin—may simulate a parietal “cortical” lesion (see below under “Sensory Loss Caused by Lesions of the Parietal Lobe”), but differs in that vibratory sense is also lost in lesions limited to the posterior columns. It should be realized therefore, that not all proprioceptive fibers ascend to the gracile and cuneate nuclei; some proprioceptive fibers leave the posterior columns in the lumbar region and synapse with secondary neurons in the spinal gray matter and ascend in the ipsilateral posterolateral funiculus. Only cutaneous fibers continue to the gracile and cuneate nuclei.


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Neurology_Adams. The usual causes of the posterior column syndrome are multiple sclerosis, vitamin B12 deficiency, copper deficiency, tabes dorsalis, and HIV and human T-lymphotropic virus (HTLV) type 1 infection. With infarction of the spinal cord in the territory of supply of the anterior spinal artery or with other lesions that affect the ventral portion of the cord predominantly, as in some cases of myelitis, one finds a loss of pain and temperature sensation below the level of the lesion but with relative or absolute sparing of proprioceptive sensation. Because the corticospinal tracts and the ventral gray matter also lie within the area of distribution of the anterior spinal artery, paralysis is a prominent feature (see Fig. 8-7). Disturbances of Sensation from Lesions of the Brainstem


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Neurology_Adams. A characteristic feature of medullary lesions is the occurrence, in many instances, of a crossed sensory disturbance, that is, a loss of pain and temperature sensation on one side of the face and on the opposite side of the body. This is accounted for by involvement of the descending spinal trigeminal tract or its nucleus and the crossed lateral spinothalamic tract on one side of the brainstem and is nearly always caused by a lateral medullary infarction (Wallenberg syndrome). In the upper medulla, pons, and midbrain, the crossed trigeminothalamic and lateral spinothalamic tracts run together; a lesion at these levels causes loss of pain and temperature sense on the opposite half of the face and body. Spontaneous and induced thermal or painful dysesthesias are often reported (“feeling as if sunburned”). In the upper brainstem, the spinothalamic tract and the medial lemniscus become confluent, so that an appropriately placed lesion causes a contralateral loss of all superficial and


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Neurology_Adams. as if sunburned”). In the upper brainstem, the spinothalamic tract and the medial lemniscus become confluent, so that an appropriately placed lesion causes a contralateral loss of all superficial and deep sensation. Cranial nerve palsies, cerebellar ataxia, and motor paralysis are almost invariably associated, as indicated in the discussion of strokes in this region (Chap. 33). In other words, a lesion in the brainstem at any level is unlikely to cause an isolated sensory disturbance.


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of the Thalamus

Neurology_Adams. of the Thalamus


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Neurology_Adams. Involvement of the VPL and VPM nuclei of the thalamus, usually because of a vascular lesion, causes loss or diminution of all forms of sensation on the opposite side of the body. Position sense is affected more frequently than any other sensory function and is usually, but not always, more profoundly reduced than loss of touch and pinprick. With partial recovery of sensation, or with an acute but incomplete lesion, spontaneous pain or discomfort (Dejerine-Roussy syndrome; thalamic pain syndrome), sometimes of the most distressing type, may appear on the affected side of the body. A stimulus may then have a diffuse, unpleasant, lingering quality. Thermal—especially cold—stimuli, emotional disturbance, loud sounds, and even certain types of music may aggravate the painful state. In spite of this overresponse to stimuli, the patient usually shows an elevated pain threshold, that is, a stronger stimulus than normal is necessary to produce a sensation of pain (hypalgesia with hyperpathia).


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Neurology_Adams. this overresponse to stimuli, the patient usually shows an elevated pain threshold, that is, a stronger stimulus than normal is necessary to produce a sensation of pain (hypalgesia with hyperpathia). The same type of pain syndrome may occasionally accompany lesions of the white matter of the parietal lobe, the medial lemniscus, or even the posterior columns of the spinal cord.


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Neurology_Adams. It should be pointed out that a symptomatic hemisensory syndrome, usually with few objective changes, occurs frequently without manifest evidence of thalamic or spinal cord damage. This particularly occurs in young women, as pointed out by Toth. A number of our patients with this benign condition have had migraine, and one, as in Toth’s series, had the antiphospholipid syndrome, but the connections between all these entities is tenuous and many cases are considered to be psychogenic or unexplained. of the Parietal Lobe


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Neurology_Adams. of the Parietal Lobe In the anterior parietal lobe syndrome (Verger-Dejerine syndrome), there are disturbances mainly of discriminative sensory functions of the opposite arm, leg, and side of the face without impairment of the primary modalities of sensation (unless the lesion is extensive and deep). Loss of position sense and sense of movement, impaired ability to localize touch and pain stimuli (topagnosia), widening of two-point threshold, and astereognosis are the most prominent findings, as described earlier in this chapter and in Chap. 21, “Clinical Effects of Parietal Lobe Lesions.”


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Neurology_Adams. Another characteristic manifestation of parietal lobe lesions is sensory inattention, extinction, or neglect. In response to bilateral simultaneous testing of symmetrical parts, using either tactile or painful stimuli, the patient may acknowledge only the stimulus on the sound side; or, if the face and hand or foot on the affected side is touched or pricked, only the stimulus to the face may be noticed. Apparently cranial structures command more attention than other less richly innervated parts. Yet each stimulus, when applied separately to each side or to each part of the affected side, is properly perceived and localized. In the case of sensory neglect, the patient ignores one side of the body and extrapersonal space contralateral to the parietal lesion, which is usually in the nondominant hemisphere. Left parietal lesions may also cause right sensory neglect, but less frequently and less profoundly. Sensory neglect or extinction, which may also occur occasionally with posterior


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Neurology_Adams. hemisphere. Left parietal lesions may also cause right sensory neglect, but less frequently and less profoundly. Sensory neglect or extinction, which may also occur occasionally with posterior column and medial lemniscus lesions, may be detected in persons who disclaim any sensory symptoms. These phenomena and other features of parietal lobe lesions are, as mentioned, considered further in Chap. 21.


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Neurology_Adams. Yet another parietal lobe syndrome, Dejerine-Mouzon, is featured by a severe impairment of the primary modalities of sensation (pain, thermal, tactile sense, but usually with relative sparing of vibratory sense) over the contralateral half of the body. Motor paralysis is variable; with partial recovery, there may be a clumsiness that resembles cerebellar ataxia. Because the sensory disorder simulates that caused by a thalamic lesion, it was called pseudothalamic by Foix and coworkers. Hyperpathia, much like that of the Dejerine-Roussy syndrome (see above), has also been observed in patients with cortical–subcortical parietal lesions. The pseudothalamic syndrome was related by Foix and colleagues to a sylvian infarct; Bogousslavsky and associates traced it to a parietal infarct caused by occlusion of the ascending parietal branch of the middle cerebral artery. In each of the aforementioned parietal lobe syndromes, if the dominant hemisphere is involved, there may be aphasia, bimanual


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Neurology_Adams. occlusion of the ascending parietal branch of the middle cerebral artery. In each of the aforementioned parietal lobe syndromes, if the dominant hemisphere is involved, there may be aphasia, bimanual tactile agnosia, or a


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Neurology_Adams. Gerstmann syndrome; with nondominant lesions, there may be anosognosia (see Chap. 21). Often with parietal lesions, the patient’s responses to sensory stimuli are variable. A common mistake, as emphasized by Critchley, is to attribute this abnormality to hysteria (see also below under “Sensory loss due to Suggestibility and Hysteria”). A lesion confined to only a part of the parietal cortex (the best examples have been caused by glancing bullet or shrapnel wounds of the skull) may result in a circumscribed loss of superficial sensation in an opposite limb, mimicking a root, or peripheral nerve lesion. Sensory Loss due to Suggestibility and Hysteria (See Also Chap. 47)


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Neurology_Adams. The possibility of suggesting sensory loss to a patient is a very real one, as has already been indicated. Hysterical patients may complain of a complete hemianesthesia—sometimes with the anatomically implausible findings of reduced hearing, sight, smell, and taste on the same side—as well as impaired vibration sense over only half the skull and sternum, most of these being anatomic impossibilities. A frequently used test to disclose this feature is performed by placing a vibrating tuning fork on each side adjacent to the middle of the forehead. The transmission of vibration through the bone ensures that loss of sensation on one side of the midline is not possible. Anesthesia of an entire limb or a sharply defined sensory loss over part of a limb, not conforming to the distribution of a root or cutaneous nerve, may also be observed. The diagnosis of hysterical hemianesthesia is best made by eliciting the other relevant symptoms of hysteria or, if this is not possible, by noting the


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Neurology_Adams. root or cutaneous nerve, may also be observed. The diagnosis of hysterical hemianesthesia is best made by eliciting the other relevant symptoms of hysteria or, if this is not possible, by noting the discrepancies between the sensory loss displayed by the patient and that which occurs as part of the known, anatomically verified sensory syndromes.


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Neurology_Adams. Sometimes, in a patient with no other neurologic abnormality or in one with a definite neurologic syndrome, one is dismayed by sensory findings that are completely inexplicable and discordant. In such cases, one must try to reason through to the diagnosis by disregarding the sensory findings or approach the finding as revealing a second disorder such as a neurofibroma of a nerve root. Laboratory Diagnosis of Somatosensory Syndromes


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Neurology_Adams. Affirmation of a clinical sensory syndromes is often possible by the application of electrophysiologic testing. Slowing and reduced amplitude of sensory nerve conduction is found with lesions of nerve, but only if the lesion lies distal to (or within) the sensory ganglion. Severe sensory loss in a neuropathic pattern with preserved sensory nerve action potentials therefore indicates a radiculopathy. Loss or slowing of the H reflex and F responses corroborates the presence of lesions in proximal parts of nerves, plexuses, and roots. By the use of somatosensory evoked potentials, it is possible to demonstrate slowing of conduction in the peripheral nerves or roots, in the pathways from spinal cord to a point in the lower medulla, in the medial lemniscus to the thalamus, and in the pathway from the thalamus to the cerebral cortex. In the context of regional sensory loss, evoked potentials find their greatest utility in demonstrating root disease when sensory nerve conduction studies are


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Neurology_Adams. the thalamus to the cerebral cortex. In the context of regional sensory loss, evoked potentials find their greatest utility in demonstrating root disease when sensory nerve conduction studies are normal; otherwise, they are used most frequently to support the diagnosis of multiple sclerosis, in which case there may or may not be corresponding sensory features. (See Chap. 2 for discussion of evoked potential testing.)


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Neurology_Adams. In practice, it is seldom necessary to examine all modalities of sensation and perception. With single peripheral nerve lesions, touch and pinprick testing are the most informative. With spinal cord disease, pinprick and thermal stimuli are most revealing of lateral column lesions; testing the senses of vibration, position, and movement, and particularly the sense of direction of a dermal stimulus, reliably indicates posterior column lesions. Touch is the least useful. In diseases of the sensory ganglia all modes of sensation, including touch, may be affected throughout the body, and this applies in general to thalamic lesions, but of course, only on the side opposite the lesion. Thus, one is guided in the selection of tests by the suspected locale of the disease. Abraira VE, Ginty DD: The sensory neurons of touch. Neuron 79:618, 2013. Bogousslavsky J, Assal G, Regli F: Aphasie afferente motrice et hemi-syndrome sensitif droite. Rev Neurol 138:649, 1982.


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Neurology_Adams. Abraira VE, Ginty DD: The sensory neurons of touch. Neuron 79:618, 2013. Bogousslavsky J, Assal G, Regli F: Aphasie afferente motrice et hemi-syndrome sensitif droite. Rev Neurol 138:649, 1982. Carmon A: Disturbances of tactile sensitivity in patients with unilateral cerebral lesions. Cortex 7:83, 1971. Carmon A, Benton AL: Tactile perception of direction and number in patients with unilateral cerebral disease. Neurology 19:525, 1969. Caselli RJ: Rediscovering tactile agnosia. Mayo Clin Proc 66:129, 1991. Corkin S, Milner B, Rasmussen T: Tactually guided maze learning in man: effects of unilateral cortical excision and bilateral hippocampal lesions. Neuropsychologia 3:339, 1965. Corkin S, Milner B, Rasmussen T: Effects of different cortical excisions on sensory thresholds in man. Trans Am Neurol Assoc 89:112, 1964. Critchley M: The Parietal Lobes. London, Arnold, 1953. Davidoff RA: The dorsal columns. Neurology 39:1377, 1989.


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Neurology_Adams. Critchley M: The Parietal Lobes. London, Arnold, 1953. Davidoff RA: The dorsal columns. Neurology 39:1377, 1989. Dyck PJ, O’Brien PC, Johnson DM, et al: Quantitation of sensory abnormality. In: Dyck PJ, Thomas PK, et al (eds): Peripheral Neuropathy, 4th ed. Philadelphia, Saunders, 2005, Chap 43. Foix C, Chavany JA, Levy M: Syndrome pseudothalamique d’origine parietale. Rev Neurol 35:68, 1927. Greaves MS, Wall PD: Pathophysiology of itching. Lancet 348:938, 1996. Keegan JJ, Garrett FD: The segmental distribution of the cutaneous nerves in the limbs of man. Anat Rec 102:409, 1948. Kibler RF, Nathan PW: A note on warm and cold spots. Neurology 10:874, 1960. Lele PP, Weddell G: The relationship between neurohistology and corneal sensibility. Brain 79:119, 1956. Lewis T, Pickering GW, Rothschild P: Centrifugal paralysis arising out of arrested blood flow to the limb, including notes on a form of tingling. Heart 16:1, 1931.


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Neurology_Adams. Lewis T, Pickering GW, Rothschild P: Centrifugal paralysis arising out of arrested blood flow to the limb, including notes on a form of tingling. Heart 16:1, 1931. Moberg E: The role of cutaneous afferents in position sense, kinaesthesia and motor function of the hand. Brain 106:1, 1983. Nathan PW, Smith MC, Cook AW: Sensory effects in man of lesions in the posterior columns and of some other afferent pathways. Brain 109:1003, 1986. Ochoa JL, Torebjork HE: Paraesthesiae from ectopic impulse generation in human sensory nerves. Brain 103:835, 1980. Ray BS, Wolff HG: Studies on pain: Spread of pain: Evidence on site of spread within the neuraxis of effects of painful stimulation. Arch Neurol Psychiatry 53:257, 1945. Roland PE, Ladegaard-Pederson H: A quantitative analysis of sensations of tension and of kinaesthesia in man. Brain 100:671, 1977.


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Neurology_Adams. Roland PE, Ladegaard-Pederson H: A quantitative analysis of sensations of tension and of kinaesthesia in man. Brain 100:671, 1977. Semmes J, Weinstein S, Ghent L, Teuber H-L: Somatosensory Changes after Penetrating Brain Wounds in Man. Cambridge, MA, Harvard University Press, 1960. Toth C: Hemisensory syndrome is associated with a low diagnostic yield and a nearly uniform benign prognosis. J Neurol Neurosurg Psychiatry 74:1113, 2003. Tower SS: Unit for sensory reception in the cornea. J Neurophysiol 3:486, 1940. Trotter W, Davies HM: Experimental studies in the innervation of the skin. J Physiol 38:134, 1909. Weddell G: The multiple innervation of sensory spots in the skin. J Anat 75:441, 1941. Yosipovitch G, Greaves MW, Schmetz M: Itch. Lancet 361:690, 2003.


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Neurology_Adams. Great auricular n.Ant. cut. n. of neckAnt. cut. ramiof thor. n’s.T23456789101112Lat. cut. ramiSupraclavicular n’s.Med. cut. n. of arm & intercostobrachial n.Med. cut. n. of forearmIliohypogastric n.Genitalbranch ofgenitofem.n.Dorsal n. of penisScrotal branch of perineal n.Obturator n.Lat.cut. n. of calf(from common peroneal n.)Superficial peroneal n.(from common peroneal n.)Deep peroneal n.(from commonperoneal n.)Intermed. & med. cut. n’s.of thigh (from femoral n.)Lat. cut. n. of thighLat. cut. of forearm(from musculocut. n.)Lower lat.cut. n. of arm(from radial n.)Axillary n.(circumflex)IIIIIIIlioinguinaln.Femoral branchof genitofemoral n.(lumbo-inguinal n.) Saphenous n.(from femoral n.)Med. & lat. plantar n’s.(from posttibial n.)Sural n.(from tibial n.)Radial n.Median n.Ulnar n.Great auricular n.GreaterLesser n.occipital nervesAnt. cut. n. of neckT2C6C53456789101112T1L1S1Post. rami oflumbar sacral& coccygeal n’s.Lat. cut. ramiPost.cut.ramiofthor.n’s.Supraclavicular n’s.Med. cut.


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Neurology_Adams. auricular n.GreaterLesser n.occipital nervesAnt. cut. n. of neckT2C6C53456789101112T1L1S1Post. rami oflumbar sacral& coccygeal n’s.Lat. cut. ramiPost.cut.ramiofthor.n’s.Supraclavicular n’s.Med. cut. n. of arm& intercostobrachial n.Post. cut. n. of forearm(from radial n.)Lat. cut. n. of forearm (from musculocut n.)Med. cut. n. of forearmObturator n.Superficial peroneal n.(from common peroneal n.)Lat. cut. n.of calf(from common femoral n.)Inf. med. cluneal n.Inf. lat.cluneal n’s.Lat. plantar n.Saphenousn.Sural n.Calcanean branchesof tibial & sural n’s.Med. plantar n.Lat. plantar n.Superficialperoneal n.Inf. med. n. of thighPost cut. n. of thighLowerLat. cut. of arm(from radial n.)Post cut. n. of arm(from radial n.)Axillary n.(circumflex)Iliohypo-gastric n.Saphenous n.(from femoral n.)Med. cut. n. of thigh(from femoral n.)Calcanean branches ofsural & tibial n’s.Sural n. (from tibial n.)Radial n.Median n.Ulnar n.}


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Neurology_Adams. Figure 8-1. The cutaneous fields of peripheral nerves. (Reproduced by permission from Haymaker W, Woodhall B: Peripheral Nerve Injuries, 2nd ed. Philadelphia, Saunders, 1953.)


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Neurology_Adams. Figure 8-2. The location and morphology of mechanoreceptors in hairy and hairless (glabrous) skin of the human hand. Receptors are located in the superficial skin, at the junction of the dermis and epidermis, and more deeply in the dermis and subcutaneous tissue. The receptors of the glabrous skin are Meissner’s corpuscles, located in the dermal papillae; Merkel disc receptors, located between the dermal papillae; and bare nerve endings. The receptors of the hairy skin are hair receptors, Merkel’s receptors (having a slightly different organization than their counterparts in the glabrous skin), and bare nerve endings. Subcutaneous receptors, beneath both glabrous and hairy skin, include Pacinian corpuscles and Ruffini endings. Nerve fibers that terminate in the superficial layers of the skin are branched at their distal terminals, innervating several nearby receptor organs; nerve fibers in the subcutaneous layer innervate only a single receptor organ. The structure of the receptor


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Neurology_Adams. skin are branched at their distal terminals, innervating several nearby receptor organs; nerve fibers in the subcutaneous layer innervate only a single receptor organ. The structure of the receptor organ determines its physiological function. (Reproduced with permission from Kandel ER, Schwartz JH, Jessell TM: Principles of Neural Science, 4th ed. New York: McGraw-Hill, 2000.)


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Neurology_Adams. Figure 8-3. Distribution of the sensory spinal roots on the surface of the body (dermatomes). (Reproduced by permission from Sinclair D: Mechanisms of Cutaneous Sensation. Oxford, UK, Oxford University Press, 1981.) Figure 8-4. Dermatomes of the upper and lower extremities, outlined by the pattern of sensory loss following lesions of single nerve roots. (Reproduced by permission from Keegan and Garrett.) Figure 8-5. The main somatosensory pathways emphasizing the posterior column–lemniscal system (thicker tract lines). See Fig. 7-2 for comparison with the spinothalamic system. EyeThumbIndexMiddleRingLittleHandWristElbowForearmArmShoulderHeadNeckHipLegTrunkFootToesGenitalsSensory homunculusMedialLateralNoseFaceUpper lipLower lipTeeth, gums, and jawTonguePharynxIntraabdominalFingers


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Neurology_Adams. Figure 8-6. The “sensory homunculus,” or cortical representation of sensation in the postcentral gyrus; compare this to the distribution of body areas in the motor cortex as shown in Fig. 3-4. (Reproduced with permission from Kandel ER, Schwartz JH, Jessel TM: Principle of Neural Science, 4th ed. New York, McGraw-Hill, 2000.) Figure 8-7. Sites of lesions of the characteristic spinal cord sensory syndromes (shaded areas indicate regions of damage). Lower right figure shows variable extent of damage to mid-axial cord but always sparing the posterior columns. Chapter 8 Disorders of Non-Painful Somatic Sensation


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Neurology_Adams. Chapter 8 Disorders of Non-Painful Somatic Sensation Of all the painful states that afflict humans, headache is undoubtedly the most frequent and rivals backache as one of the most common reasons for seeking medical help. In fact, there are so many cases of headache that dedicated headache clinics have been established in many medical centers. In addition to its frequency in general practice, many headaches are caused by medical rather than neurologic diseases and the subject is the legitimate concern of the general physician. Yet there is always the question of intracranial disease so that it is difficult to approach the subject without knowledge of neurology.


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Neurology_Adams. Why so many pains are centered in the head is a question of some interest. Several explanations come to mind. For one thing, the face and scalp are more richly supplied with pain receptors than many other parts of the body, perhaps to protect the precious contents of the skull. Also, the nasal and oral passages, the eye, and the ear—all delicate and highly sensitive structures—reside here and must be protected; when affected by disease, each is capable of inducing pain in its own way. Finally, there is great concern by patients about what happens to the head perhaps more than other parts of the body because headache raises the specter of brain tumor or other cerebral disease.


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Neurology_Adams. Semantically, the term headache encompasses all aches and pains located in the head, but in practice, its application is restricted to discomfort in the region of the cranial vault. Facial, lingual, and pharyngeal pains are discussed in the latter part of this chapter and separately in Chap. 44, because they pertain to the cranial nerves.


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Neurology_Adams. In the introductory chapter on pain, reference was made to the necessity, in dealing with any painful state, of determining its quality, severity, location, duration, and time course as well as the conditions that produce, exacerbate, or relieve it. In the case of headache, a detailed history following these lines will determine the diagnosis more often than will the physical examination or imaging. Nevertheless, a few aspects of the examination are worth emphasizing. For example, auscultation of the skull may rarely disclose a bruit (with large arteriovenous malformations); palpation may disclose the tender, hardened or elevated arteries of temporal arteritis; sensitive areas overlying a cranial metastasis or an inflamed paranasal sinus may be apparent; or there may be a tender occipital nerve. Examination of neck flexion may reveal meningitis; however, apart from such special instances, examination of the head itself, although necessary, seldom discloses the diagnosis.


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Neurology_Adams. The quality of cephalic pain is essential to diagnosis but the sensation may be difficult for the patient to describe. When asked to compare the pain to some other sensory experience, the patient may allude to tightness, aching, pressure, burning, bursting, sharpness, or stabbing. Among the most important aspects is whether the headache is pulsatile, usually implying migraine, but one must keep in mind that patients sometimes use the word throbbing to refer to a waxing and waning of the headache without any relation to the pulse, or use the term to transmit the severity of pain.


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Neurology_Adams. Similarly, statements about the intensity of the pain are inherently subjective, as they reflect as much the patient’s temperament, attitudes, and customary ways of experiencing and reacting to pain. One useful index of severity is the degree to which the pain has incapacitated the patient. A severe migraine attack seldom allows the migraineur to perform the day’s work. Other rough indices of the severity of headache are its propensity to awaken the patient from sleep or to prevent sleep, and autonomic reactions to the pain such as sweating and tachycardia. The most intense cranial pains are those associated with meningitis and subarachnoid hemorrhage, which can have grave consequences, but also migraine, cluster headache, or tic douloureux that do not have the same implications.


Neurology_Adams

Neurology_Adams. Data regarding the location of a headache is informative. Migraine headache is unilateral in two-thirds of attacks and is commonly associated with nausea, vomiting, and sensitivity to light, sound, and smells. Inflammation of an extracranial artery from temporal arteritis causes pain localized to the site of the vessel. Lesions of the paranasal sinuses, teeth, eyes, and upper cervical vertebrae induce a less sharply localized pain but still one that is referred to a certain region, usually the forehead or maxilla or around the eyes. Intracranial lesions in the posterior fossa generally cause pain in the occipitonuchal region and usually are homolateral if the lesion is one-sided. Supratentorial lesions induce frontotemporal pain, or approximate the site of the lesion. Localization, however, may also be deceiving. Pain in the frontal regions may be caused by such diverse lesions and mechanisms as glaucoma, sinusitis, thrombosis of the vertebral or basilar artery, pressure on the


Neurology_Adams

Neurology_Adams. however, may also be deceiving. Pain in the frontal regions may be caused by such diverse lesions and mechanisms as glaucoma, sinusitis, thrombosis of the vertebral or basilar artery, pressure on the tentorium, and increased intracranial pressure. Similarly, ear pain may signify disease of the ear itself, but as often, it is referred from other regions, such as the throat, cervical muscles, spine, or structures in the posterior fossa. Periorbital and supraorbital pain, while usually indicative of local disease, may reflect dissection of the cervical portion of the internal carotid artery. Headaches localized to the vertex or biparietal regions are infrequent and should raise the suspicion of sphenoid or ethmoid sinus disease or thrombosis of the superior sagittal venous sinus.


Neurology_Adams

Neurology_Adams. The mode of onset, the variation of the pain over time, and duration of the headache, with respect both to a single attack and to the profile of the headache over a period of years, are also useful data. At one extreme, the headache of subarachnoid hemorrhage (caused by a ruptured aneurysm) occurs as an abrupt attack that attains its maximal severity in a matter of seconds or minutes, or, in the case of meningitis, it may come on more gradually, over several hours or days. Simulating the rapid onset, severe headache of subarachnoid hemorrhage are a group of “thunderclap headaches” of diverse causes but principally cerebral venous thrombosis and vasospasm syndromes. Brief sharp pain, lasting a few seconds, in the eyeball (ophthalmodynia) or cranium (“ice-pick” pain) and “ice-cream headache” caused by pharyngeal cooling is more common in migraineurs and are significant only by reason of their benignity.


Neurology_Adams

Neurology_Adams. With regard to characteristic temporal patterns, migraine of the typical type usually has its onset in the early morning hours or in the daytime, reaches its peak of severity over several to 30 min, and lasts, unless treated, for 4 to 24 h, occasionally longer. Often, it is terminated by sleep. A migrainous patient having several attacks per week usually proves to have a chronic form of migraine or a combination of migraine and analgesic “overuse headache,” meaning that the headache returns when the effect of the drug has worn off, or rarely, some unexpected intracranial lesion. By contrast, cluster headache is characterized by the occurrence of unbearably severe unilateral orbitotemporal pain coming on within 1 or 2 h after falling asleep or at predictable times during the day and recurring nightly or daily for a period of several weeks to months; usually an individual attack of “cluster” dissipates in 30 to 45 min but may occasionally last several hours. The headache of intracranial


Neurology_Adams

Neurology_Adams. nightly or daily for a period of several weeks to months; usually an individual attack of “cluster” dissipates in 30 to 45 min but may occasionally last several hours. The headache of intracranial tumor may appear at any time of the day or night; it may interrupt sleep, vary in intensity, and last a few minutes to hours as the tumor raises intracranial pressure. With posterior fossa masses, the headache tends to be worse in the morning, on awakening. Tension headaches (now called “tension-type headache”) can persist with varying intensity for weeks to months or even longer; when such headaches are protracted, there is often an associated depressive illness. In general, headaches that have recurred regularly for many years prove to be migraine or tension in type.


Neurology_Adams

Neurology_Adams. The relationship of headache to certain biologic events and also to certain precipitating, aggravating, or relieving factors can be of great significance in diagnosis. Headaches that occur regularly in the premenstrual period are usually generalized and mild in degree, but attacks of migraine may also occur at this time (catamenial migraine). Headaches that have their origin in cervical spine disease are most typically intense after a period of inactivity, such as a night’s sleep, and the first movements of the neck are stiff and painful. Headache, or more often face ache, from infection of the nasal sinuses may appear upon awakening or in midmorning and is characteristically worsened by stooping and changes in atmospheric pressure; there is associated midfrontal or maxillary tenderness. Eyestrain after long-sustained periods of reading, or exposure to the glare of video displays, may be associated with head pain but it is transient and not an important cause of headache. In certain


Neurology_Adams

Neurology_Adams. Eyestrain after long-sustained periods of reading, or exposure to the glare of video displays, may be associated with head pain but it is transient and not an important cause of headache. In certain individuals, alcohol, intense exercise (such as weight lifting), stooping, straining, coughing, and sexual intercourse are known to initiate a bursting (thunderclap) headache, lasting a few seconds to minutes. If a headache is made worse by sudden movement or by coughing or straining, an intracranial source is tentatively suggested. Migraine often occurs several hours or a day following a period of intense activity and stress (“weekend,” or “letdown” migraine). Some patients have discovered that their migraine is relieved momentarily by gentle compression of the carotid or superficial temporal artery on the painful side, and others report that the carotid near the angle of the jaw is tender during the headache. Pain that is noticed when the scalp is stroked in combing or fixing the hair


Neurology_Adams

Neurology_Adams. artery on the painful side, and others report that the carotid near the angle of the jaw is tender during the headache. Pain that is noticed when the scalp is stroked in combing or fixing the hair (allodynia) is common in migraine but could be a symptom of inflammation of the temporal arteries (temporal arteritis). Certain medications, most vasodilators such as nitroglycerin and dipyridamole but also monosodium glutamate, are apt to cause headaches. The headaches that follow a period or excessive alcohol (hangover) or a concussion are well known. In many of these instances, a propensity for migraine may create a susceptibility to an induced headache.


Neurology_Adams

Neurology_Adams. Our understanding of headache has been augmented by observations made during operations on the brain by Ray and Wolff. These observations inform us that only certain cranial structures are sensitive to noxious stimuli: (1) skin, subcutaneous tissue, muscles, extracranial arteries, and external periosteum of the skull; (2) the delicate structures of the eye, ear, nasal cavities, and paranasal sinuses; (3) intracranial venous sinuses and their large tributaries because they are intradural; (4) parts of the dura at the base of the brain and the arteries within the dura, particularly the proximal parts of the anterior and middle cerebral arteries and the intracranial segment of the internal carotid artery; (5) the middle meningeal and superficial temporal arteries; and (6) the first three cervical nerves and cranial nerves as they pass through the dura. Interestingly, pain is practically the only sensation produced by stimulation of these structures. Much of the pia-arachnoid, the


Neurology_Adams

Neurology_Adams. cervical nerves and cranial nerves as they pass through the dura. Interestingly, pain is practically the only sensation produced by stimulation of these structures. Much of the pia-arachnoid, the parenchyma of the brain, and the ependyma and choroid plexuses lack sensitivity.


Neurology_Adams

Neurology_Adams. The reference sites of pain from the aforementioned structures are important in understanding the genesis of cranial pain. Pain that arises from distention of the middle meningeal artery is projected to the back of the eye and temporal area. Pain from the intracranial segment of the internal carotid artery and proximal parts of the middle and anterior cerebral arteries is felt in the eye and orbitotemporal regions. The pathways whereby cephalic sensory stimuli are transmitted to the central nervous system (CNS) are the trigeminal nerves, particularly their first and, to some extent, second divisions, which convey impulses from the forehead, orbit, anterior and middle fossae of the skull, and the upper surface of the tentorium. The sphenopalatine branches of the facial nerve convey impulses from the nasoorbital region. The ninth and tenth cranial nerves and the first three cervical nerves transmit impulses from the inferior surface of the tentorium and all of the posterior fossa. The


Neurology_Adams

Neurology_Adams. from the nasoorbital region. The ninth and tenth cranial nerves and the first three cervical nerves transmit impulses from the inferior surface of the tentorium and all of the posterior fossa. The tentorium roughly demarcates the trigeminal from the cervical–vagal–glossopharyngeal innervation zones. The central sensory connections, which ascend through the brainstem or the cervical spinal cord and brainstem to the thalamus, are described in Chaps. 7 and 8. Sympathetic fibers from the three cervical ganglia and parasympathetic fibers from the sphenopalatine and otic ganglia are mixed with the trigeminal and other sensory fibers. These assume importance in certain headache syndromes considered further on.


Neurology_Adams

Neurology_Adams. There may be local tenderness of the scalp at the site of the referred pain. Dental or temporomandibular joint pain impulses are carried by the second and third divisions of the trigeminal nerve. With the exception of the cervical portion of the internal carotid artery, from which pain is referred to the eyebrow and supraorbital region, and the upper cervical spine, from which pain may be referred to the occiput, pain from disease in extracranial parts of the body is not referred to the head. There are, however, rare instances of angina pectoris that may produce discomfort at the cranial vertex or adjacent sites and, of course, in the jaw. Mechanisms of Cranial Pain


Neurology_Adams

Neurology_Adams. Mechanisms of Cranial Pain The studies of Ray and Wolff demonstrated that relatively few mechanisms are operative in the genesis of cranial pain. More specifically, intracranial mass lesions cause headache if they deform, displace, or exert traction on vessels and dural structures at the base of the brain, and this may happen long before intracranial pressure rises. In fact, artificially raising the intraspinal and intracranial pressure by the subarachnoid or intraventricular injection of sterile saline solution does not consistently result in headache. This has been interpreted to mean that raised intracranial pressure does not cause headache—a questionable conclusion when one considers the relief of headache in some patients that follows lumbar puncture and lowering of the cerebrospinal fluid (CSF) pressure, particularly after subarachnoid hemorrhage. Actually, most patients with high intracranial pressure complain of bioccipital and bifrontal headaches that fluctuate in severity.


Neurology_Adams

Neurology_Adams. Dilatation of intracranial or extracranial arteries (and possibly sensitization of these vessels), of whatever cause, is likely to produce headache. The headaches that follow seizures and ingestion of alcohol are probably all caused by cerebral vasodilatation. Nitroglycerin, nitrites in cured meats (“hot-dog headache”), and monosodium glutamate in some foods may cause headache by the same mechanism. It is possible that the throbbing or steady headache that accompanies febrile illnesses has a vascular origin as well; it is likely that the increased pulsation of meningeal vessels activates pain-sensitive structures within their walls or around the base of the brain. Febrile headache may be generalized or predominate in the frontal or occipital regions and is relieved on one side by carotid or superficial temporal artery compression and on both sides by jugular vein compression. Like migraine, it is also increased by shaking the head. Certain systemic infectious agents, enumerated


Neurology_Adams

Neurology_Adams. or superficial temporal artery compression and on both sides by jugular vein compression. Like migraine, it is also increased by shaking the head. Certain systemic infectious agents, enumerated further on, have a tendency to cause severe headache.


Neurology_Adams

Neurology_Adams. A similar mechanism may be operative in the severe, bilateral, throbbing headaches associated with extremely rapid rises in blood pressure, as occurs with pheochromocytoma, malignant hypertension, sexual activity, and in patients being treated with monoamine oxidase inhibitors. Mild to moderate degrees of chronic hypertension, however, do not cause headaches despite a popular notion to the contrary. So-called cough and exertional headaches may also have their basis in the distention of intracranial vessels.


Neurology_Adams

Neurology_Adams. For many years, following the investigations of Harold Wolff, the headache of migraine was attributed to dilatation of the extracranial arteries. Now, it appears that this is not a constant relationship and that the headache is of complex intracranial as much as extracranial origin, perhaps related to the sensitization of blood vessels and their surrounding structures. Activation of the trigeminovascular system (the trigeminal nerves and the blood vessels they supply), leading to an inflammatory response that is generated by local neural mechanisms, “neurogenic inflammation,” has also been assigned a role in migraine headache. These and other theories of causation are summarized by Cutrer and discussed further on in this chapter in the section on migraine.


Neurology_Adams

Neurology_Adams. With regard to cerebrovascular diseases causing head pain, the extracranial temporal and occipital arteries, when involved in giant cell arteritis (cranial or “temporal” arteritis), give rise to severe, persistent headache, at first localized on the scalp and then more diffuse. Most strokes caused by vascular occlusion do not cause head pain. However, with occlusion or dissection of the vertebral artery, there may be pain in the upper neck or postauricular area; basilar artery thrombosis causes pain to be projected to the occiput and sometimes to the forehead; and the ipsilateral eye and brow, and the forehead above it are the most common sites of projected pain from dissection of the carotid artery and occlusion of the stem of the middle cerebral arteries. Expanding intracranial aneurysms of the posterior communicating or distal internal carotid arteries very often cause pain projected to the eye. The distinctive headache caused by aneurysmal rupture is mentioned below and in a


Neurology_Adams

Neurology_Adams. of the posterior communicating or distal internal carotid arteries very often cause pain projected to the eye. The distinctive headache caused by aneurysmal rupture is mentioned below and in a separate section later in the chapter.


Neurology_Adams

Neurology_Adams. Infection or blockage of paranasal sinuses is accompanied by pain over the affected maxillary or frontal sinuses. Usually it is associated with tenderness of the skin and cranium in the same distribution. Pain from the ethmoid and sphenoid sinuses is localized deep in the midline behind the root of the nose or occasionally at the vertex (especially with disease of the sphenoid sinus). The mechanism in these cases involves changes in pressure and irritation of pain-sensitive sinus walls.


Neurology_Adams

Neurology_Adams. With frontal and ethmoidal sinusitis, the pain tends to be worse on awakening and gradually subsides when the patient is upright; the opposite pertains with maxillary and sphenoidal sinusitis. These relationships are believed to disclose their mechanism; pain is ascribed to filling of the sinuses and its relief to their emptying, induced by the dependent position of the ostia. Bending over intensifies the pain by causing changes in pressure, as does blowing the nose and air travel, especially on descent, when the relative pressure in the blocked sinus rises. Sympathomimetic drugs, such as phenylephrine hydrochloride, which reduce swelling and congestion, tend to relieve the pain. However, the pain may persist after all purulent secretions have disappeared, probably because of persistent inflammation of the membranes, or blockage of the orifices and dissipation of air from the blocked sinus, so called vacuum sinus headaches.


Neurology_Adams

Neurology_Adams. Headache of ocular origin, located as a rule in the orbit, forehead, or temple, is of the steady, aching type and tends to follow prolonged use of the eyes in close work. However, cranial pain is too frequently attributed to ocular causes, particularly if the external appearance of the sclera and conjunctiva are normal. The main faults are hypermetropia and astigmatism (rarely myopia), which result in sustained contraction of extraocular as well as frontal, temporal, and even occipital muscles. In the uncommon and overemphasized circumstance of a refractive error causing headache, correction rapidly ameliorates the headache. Traction on the extraocular muscles or the iris during eye surgery evokes pain. Patients who develop diplopia from neurologic causes or are forced to use one eye because the other has been occluded by a patch often complain of frontal headache. Another mechanism is involved in iridocyclitis and in acute angle closure glaucoma, in which raised intraocular pressure


Neurology_Adams

Neurology_Adams. the other has been occluded by a patch often complain of frontal headache. Another mechanism is involved in iridocyclitis and in acute angle closure glaucoma, in which raised intraocular pressure causes steady, aching pain in the region of the eye, radiating to the forehead. When acute angle closure glaucoma causes headache, the sclera is invariably red. Dilating the pupil risks precipitating angle closure glaucoma, a situation that can be reversed by the administration of pilocarpine 1 percent drops.


Neurology_Adams

Neurology_Adams. Headaches that accompany disease of ligaments, muscles, and apophysial joints in the upper part of the cervical spine are referred to the occiput and nape of the neck on the same side and sometimes to the temple and forehead. These headaches have been reproduced by the injection of hypertonic saline solution into the affected ligaments, muscles, and facet joints and are comparable to the regions of sclerotogenous referred pain that is discussed in Chap. 7. Such pains are especially frequent in late life because of the prevalence of degenerative changes in the cervical spine and tend also to occur after whiplash injuries or other forms of sudden flexion, extension, or torsion of the head on the neck. If the pain is arthritic in origin, the first movements after the individual has been still for some hours are stiff and painful. The pain of fibromyalgia, a controversial entity, is characterized by tender areas near the cranial insertion of cervical and other muscles. There are no


Neurology_Adams

Neurology_Adams. still for some hours are stiff and painful. The pain of fibromyalgia, a controversial entity, is characterized by tender areas near the cranial insertion of cervical and other muscles. There are no pathologic data as to the nature of these vaguely palpable and tender regions, and it is uncertain whether the pain actually arises in them. They may represent only the deep tenderness felt in the region of referred pain or the involuntary secondary protective spasm of muscles. Massage of muscles, heat, and injection of the tender spots with local anesthetic has unpredictable effects but relieves the pain in some cases. Unilateral occipital headache is often misinterpreted as occipital neuralgia (see further on).


Neurology_Adams

Neurology_Adams. The headache of meningeal irritation (usually due to infection or hemorrhage) is typically acute in onset, usually severe, generalized, deep seated, constant, and associated with stiffness of the neck, particularly on forward bending of the neck. It has been ascribed to increased intracranial pressure; indeed, the withdrawal of CSF may afford some relief. However, dilatation and inflammation of meningeal vessels and the chemical irritation of pain receptors in the large vessels and meninges by endogenous chemical agents, particularly serotonin and plasma kinins, are probably more important factors in the production of pain and spasm of the neck extensors. In the chemically induced meningitis from rupture of an epidermoid cyst, for example, the spinal fluid pressure is usually normal, but the headache is severe. Meningeal irritation or inflammation may also be chronic and have as its main feature a concurrently ongoing headache.


Neurology_Adams

Neurology_Adams. A distinctive type of headache is produced by aneurysmal subarachnoid hemorrhage; it is very intense and very sudden in onset and is usually associated with vomiting and neck stiffness. Other causes of an identical syndrome discussed further on, of what has been called “thunderclap headache,” simulate this disease (see Chap. 33). Among them are a type of diffuse cerebrovascular spasm, spontaneous or the result of sympathomimetic drugs, extracranial vascular dissection of the carotid or vertebral arteries, and cerebral venous thrombosis. There are also varieties of exertional headaches, noted below, that cause the thunderclap pattern.


Neurology_Adams

Neurology_Adams. Lumbar puncture (LP) and spontaneous low CSF pressure headache, as elaborated in Chap. 2, is characterized by a steady occipitonuchal and frontal pain coming on within a few minutes after arising from a recumbent position (orthostatic headache) and is relieved within a minute or two by lying down. Its cause is a persistent leakage of CSF into the lumbar tissues through the needle track, or a tear of the meninges that may be spontaneous or induced by spinal trauma. The CSF pressure is low (often zero in the lateral decubitus position), and installation of an epidural “blood patch” relieves the headache. Usually this type of headache is increased by compression of the jugular veins but is unaffected by digital obliteration of the carotid artery. It is likely that, in the upright position, a low intraspinal and negative intracranial pressure permits caudal displacement of the brain, with traction on dural attachments and dural sinuses. Pannullo and colleagues, with MRI, have demonstrated


Neurology_Adams

Neurology_Adams. low intraspinal and negative intracranial pressure permits caudal displacement of the brain, with traction on dural attachments and dural sinuses. Pannullo and colleagues, with MRI, have demonstrated this downward displacement of the cranial contents. “Spontaneous” low-pressure headache may follow a cough, sneeze, strain, or athletic injury, sometimes as a result of rupture of the arachnoid sleeve along a nerve root (see “Spontaneous Intracranial Hypotension” in Chap. 29). Less frequently, LP is complicated by severe stiffness of the neck and pain over the back of the neck and occiput (see “Lumbar Puncture Headache” in Chap. 2); a second spinal tap in some instances discloses slight pleocytosis but no decrease in glucose—a sterile meningitis. This benign reaction must be distinguished from the rare occurrence of meningitis caused by introduction of bacteria through a rent in the meninges that has allowed both escape of spinal fluid and ingress of bacteria.


Neurology_Adams

Neurology_Adams. Headaches that are aggravated by lying down or lying on one side occur with acute and chronic subdural hematoma and with some brain masses, particularly those in the posterior fossa. The headache of subdural hematoma, when it occurs, is dull and unilateral, perceived over most of the affected side of the head. The global and nuchal headaches of idiopathic intracranial hypertension (pseudotumor cerebri) are also generally worse in the supine position (Chap. 29). In all these states of raised intracranial pressure, headaches are typically worse in the early morning hours after a long period of recumbency. Further on, we discuss the relative infrequency of headache as a result of brain tumor.


Neurology_Adams

Neurology_Adams. Exertional headaches, for example those that are associated with sexual activity or weight lifting, are usually benign but they are sometimes related to pheochromocytoma, arteriovenous malformation, or other intracranial lesions, in addition to the aforementioned subarachnoid hemorrhage from ruptured aneurysm and arterial dissection. The same usually benign nature applies to headaches induced by stooping and at worst, are accounted for by sinus infection but there are exceptions and subdural hematoma is a known cause (see further on).


Neurology_Adams

Neurology_Adams. The clinician’s first goal when confronted with a patient with cranial pain is to determine if the headache is primary, in which head pain is the only identifiable disease, or if it is a secondary cranial pain. The main primary headache syndromes are migraine, tension-type headache, cluster headache, and the trigeminal–sympathetic migraine variants of migraine or cluster. These primary headache disorders tend to be chronic, recurrent, and unattended by other symptoms and signs of neurologic disease. Familiarity with the variety of symptoms, temporal profiles, and accompanying features of the primary headache disorders, and the proclivity for many of them to be familial, assist in identifying them from the patient’s description. There should be little difficulty in recognizing the secondary headaches of diseases such as glaucoma, purulent sinusitis, subarachnoid hemorrhage, and bacterial or viral meningitis provided that these sources of headache are kept in mind. A fuller account of


Neurology_Adams

Neurology_Adams. headaches of diseases such as glaucoma, purulent sinusitis, subarachnoid hemorrhage, and bacterial or viral meningitis provided that these sources of headache are kept in mind. A fuller account of these types of “secondary” headache syndromes is given in later chapters of the book, where the underlying diseases are described. All other headaches that by their localization, quality of pain, and precipitating characteristics do not conform to one of the primary types should be suspected of being symptomatic of a cranial, cervical, or systemic disorder. Nonetheless, in many instances no such underlying cause will be found after investigation.