serum immunoelectrophoresis, Ca, P, acid and alkaline phosphatase, prostate-specific antigen (if metastatic carcinoma of the prostate is a diagnostic possibility), and rheumatoid factor. Tuberculin skin test and, in endemic areas, Brucella antibody test should be carried out if there is a suspicion of chronic infectious disease. Plain films of the spine, bone scans, CT scans with or without enhancement or myelography, 102 PART II / CARDINAL MANIFESTATIONS OF NEUROLOGIC DISEASE FIG. 11-1 (1) Costovertebral angle (renal pain). (2) Spinous process and interspinous ligament. (3) Region of L5–S1 articular facet (facet joint pain). (4) Dorsum of sacrum. (5) Region of iliac crest. (6) Iliolumbar angle. (7) Spinous processes of fifth lumbar to first sacral vertebrae (tender- ness ϭ metastasis, faulty posture or occasionally spina bifida occulta). (8) Region between posterior superior and posterior inferior spines. Sacroiliac ligaments (tenderness ϭ sacroiliac sprain, often tender with fifth lumbar to first sacral disc). (9) Sacrococcygeal junction (tender- ness ϭ sacrococcygeal injury, i.e., sprain or fracture). (10) Region of sacrosciatic notch (tenderness ϭ fourth to fifth lumbar disc rupture and sacroiliac sprain). (11) Sciatic nerve trunk–sciatic notch (tenderness ϭ ruptured lumbar disc or sciatic nerve lesion). 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 102 MRI, and, in cases of discogenic disease, electromyography, nerve con- duction studies, and sensory evoked potentials are important ancillary procedures. Myelography is customarily reserved for patients in whom there is a strong suspicion of ruptured disc, tumor, or spinal stenosis and a likelihood of surgery. Common Conditions Causing Low-Back Pain The age of the patient makes certain diagnostic possibilities more or less likely. Sprains, postural abnormalities (scoliosis, kyphosis), con- genital malformations (e.g., spondylolisthesis and spondylolysis), and osteochondritis (Scheuermann disease) are the most frequent causes of chronic back pain in childhood and adolescence. Lumbosacral sprains, discogenic disease, rheumatoid spondylitis, ankylosing spondylitis, and trauma are the predominant sources of back pain in early and middle adult years. Degenerative arthropathy (“arthritis”), stenosing spondylo- sis, osteoporosis with vertebral collapse, and metastatic tumor tend to occur in older people. Lumbosacral strain or sprain At any age, but mostly in physically vigorous individuals, this disorder may cause intense low-back pain and muscle spasm. Plain films of the lumbosacral region are usually unre- vealing. Unless there are paresthesias, weakness unrelated to pain, or reflex changes, there is no way of deciding whether this condition is due to a prolapsed disc or to a ligamentous or muscular lesion (low- back strain). Bed rest, the application of cold and heat, and sufficient analgesic medication relieve the pain in a few days. Hospitalization is only a matter of convenience. A history of one or several such episodes is often elicited in patients who are later found to have disc disease. Spondylolisthesis This disorder is one in which a vertebral body, along with its pedicles and articulatory processes, slips forward on the verte- bra below (usually L5 on S1, less often L4 on L5). It reveals itself in late childhood and adolescence and at first may cause little difficulty. Later, low-back pain, limitation of motion, a palpable “step” of the spinous process forward from the one below, and an exaggerated lum- bar lordosis are the usual manifestations. In severe cases, the lower lumbar roots may be compressed, with slight weakness or sensory changes in the legs, diminished ankle reflexes, and disturbances of bladder function. The symptoms are increased by standing and walking, like those of lumbar stenosis (see below). Treatment is surgical. Spondylolysis is the name given to a common genetic defect of the pars interarticularis (the segment at the junction of pedicle and lamina) of the lower lumbar vertebrae. The defect predisposes to fracture at this location. The defect is occasionally unilateral but far more often bilat- eral. In the latter form, the vertebral body, pedicles, and superior artic- CHAPTER 11 / PAIN IN THE BACK, NECK, AND EXTREMITIES 103 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 103 ular facets move anteriorly, in which case the disorder results in spondylolisthesis. Herniated intervertebral discs Trauma (usually a flexion injury) or fraying of the annulus fibrosus and posterior longitudinal ligaments allows the soft nucleus pulposus to extrude posterolaterally into the spinal canal and compress a spinal root. The injury need not be severe because of underlying degenerative changes; a sudden twist or lifting from a flexed position of the trunk may be sufficient. The sites of rup- ture are usually at L5–S1 and L4–L5 and are progressively less frequent at the upper lumbar and lower thoracic levels. The other common sites are C6–C7, C5–C6 and C4–C5. Of importance is the fact that bulging of the disc in itself is not a cause of any significant pain or radicular symptoms. Usually pain and paresthesias are more conspicuous than weakness, although weakness can be severe with anterior root compression. Despite overlapping effects, one finds S1 lesions to weaken plantar (dorsi) flexors; L5, extensors of ankle and big toe; L4, ankle evertors; L3, knee extensors; L2, thigh adductors; and L1, hip flexors. Protrusion of the L4–L5 disc, by compressing the L5 root, causes sci- atica with pain extending along the lateral surface of the thigh and calf and dorsal surface of the foot and first three toes. With an L5–S1 disc (compression of S1), the pain is in the posterior thigh and calf, lateral border of the foot, and fourth and fifth toes; the ankle jerk is reduced or absent. Straight-leg raising stretches L5 and S1 roots, hence the pres- ence of a Lasègue sign. With an L3–L4 disc, the pain extends to the anterior thigh and anteromedial leg into the knee, and the knee jerk is diminished. Large central disc protrusion may cause bilateral symp- toms, with severe weakness of the legs and paralysis of bladder and bowel (cauda equina syndrome). The configurations of root compres- sions by protruded discs are illustrated in Fig. 11-2. Bed rest usually relieves the pain of root compression. If there is a large free fragment the patient may be most comfortable in the seated or standing position and bed rest may fail. If bed rest fails, MRI or CT scan with or without myelography confirms the diagnosis and serves as a guide to hemilaminectomy and excision of disc tissue. If diagnostic procedures disclose a protruded disc, a protracted period of conserva- tive therapy (rest for 2 weeks and analgesics) should be tried before resorting to laminectomy. Epidural injection of corticosteroids may give temporary relief. Unremitting sciatica with evidence of L5 or S1 root involvement responds to appropriate surgery 9 times out of 10. A large central protrusion with signs of cauda equina compression de- mands immediate MRI or myelography and surgical removal. Only about 1 percent of patients with low-back pain have unmistak- able signs of root compression that cannot be relieved by conservative measures and requires surgical decompression. Of those operated upon, 104 PART II / CARDINAL MANIFESTATIONS OF NEUROLOGIC DISEASE 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 104 as many as 10 percent in some series need further surgery, and as many as 25 percent are left with troublesome back pain (“failed back syn- drome”; see the Principles for details). Degenerative arthropathy of lumbar spine Wear and tear and re- peated subclinical trauma are blamed for degenerative changes in the most mobile parts of the spine (low cervical and lumbar). This leads to osteophyte formation, both anteriorly and posteriorly into the spinal canal, infolding and thickening of the posterior longitudinal ligament, bulging of discs, and thickening of the ligamentum flavum—all leading to segmental pain, stiffness, and limitation of motion and, at times, to stenosis of the lumbar spinal canal (lumbar spondylosis, or lumbar stenosis). Pain in the affected region is associated with stiffness and limitation of motion. Treatment follows conservative lines if no stenotic compression of roots is present. Superimposition of the osteoarthritic changes on a congenitally narrower-than-normal canal may cause com- pression of lumbosacral roots. CHAPTER 11 / PAIN IN THE BACK, NECK, AND EXTREMITIES 105 FIG. 11-2 Mechanisms of compression of the fifth lumbar and first sacral roots. A lateral disc protrusion at the L4–L5 level usually involves the fifth lumbar root and spares the fourth; a protrusion at L5–S1 involves the first sacral root and spares the fifth lumbar root. Note that a more medially placed disc protrusion at the L4–L5 level may involve the fifth lumbar root as well as the first (or second and third) sacral root. 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 105 Patients may have pain in the low back with radiation into thighs and legs. Typically, the pain increases on standing and walking and may resemble the intermittent claudication associated with vascular disease. Weakness and numbness of the feet are added in some cases. Sitting and flexing the trunk reduce or abolish the symptoms. Weakness and reflex loss in the legs may be brought out by having the patient walk one or two blocks or sit in a chair and attempt to touch his toes with legs extended. The neurologic signs may be localized to the roots by EMG of paraspinal muscles and conduction studies of proximal nerves. Other conditions that narrow the lumbar spinal canal will produce the same syndrome. The most frequent causes, after lumbar spondylosis, are central disc protrusion and spondylolisthesis. Surgical decompres- sion gives satisfactory relief. For discussion of visceral pain referred to the spine, see the Principles. Spinal cord and column, and other intraspinal tumors These impor- tant causes of back pain are considered in Chap. 43. NECK AND SHOULDER-ARM PAIN One must distinguish among diseases of the cervical spine (spondylo- sis, herniated disc), diseases of the brachial plexus (cervical rib, tho- racic outlet syndrome, inflammation and neoplastic invasion), and diseases of the shoulder joint (bursitis, rotator cuff syndrome). Usually the symptoms indicate whether the pain originates in the neck or shoul- der. If in the neck, the pain is felt in or near the spine; movements of the head are restricted in range and aggravate the pain. If in the shoul- der, the pain is localized there and is worsened by lifting, abducting, or rotating the upper arm. More deceptive is the relatively rare thoracic outlet syndrome, in which the pain is mainly in the shoulder and up- per arm or inner parts of the hand and forearm. On occasion, the pain of the carpal tunnel syndrome is referred to the region of the biceps muscle. Cervical Disc Protrusion This may result from injury, especially with hyperextension of the neck (as in diving, whiplash, and head injury), or it may develop without explanation. A lateral protrusion at C5–C6 compresses the C6 root. There is pain along the ridge of the trapezius and tip of the shoulder, with radiation to the anterior part of the upper arm, radial forearm, and often the thumb and index finger, and there are paresthesias and mild sensory impairment in the same regions. The biceps and supinator reflexes are diminished, and there may be slight weakness in flexion of the forearm and external rotation of the shoulder. 106 PART II / CARDINAL MANIFESTATIONS OF NEUROLOGIC DISEASE 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 106 Protrusion of the disc between C6 and C7, compressing the C7 root, causes pain in the shoulder blade, with radiation into the pectoral region, axilla, posterolateral aspect of the upper arm, dorsal forearm, and index and middle fingers; paresthesias and sensory loss correspond to the distribution of the pain. There may be weakness in extension of the forearm and a diminished or absent triceps reflex. Rupture of a disc may occur at other cervical levels, but that at C6–C7 accounts for 70 percent of cases and that at C5–C6 for 20 per- cent. Treatment follows along the same lines as were indicated for lumbar disc disease. In the case of cervical root compression, immobilization of the neck with a soft collar or by traction with a halter is often help- ful. Surgical discectomy is highly successful in cases of recalcitrant pain. Degenerative Disease of the Cervical Spine Osteoarthritis, the most common member of this group, affects men more often than women. Not well understood is its tendency to worsen abruptly and to induce symptoms of radicular disease. This suggests trauma or an inflammatory joint change, but evidence for either is usu- ally lacking. The usual symptoms are cervical aching pain radiating into the occiput, shoulder, and upper arms and restriction of movement of the head. With advanced disease and the formation of bony ridges (ossi- fication of protruded disc material), the spinal cord may be compressed (cervical spondylosis), resulting in spastic weakness and loss of posi- tion and vibratory sense in the legs. Osteophytic spur formation in and around the vertebral foramina may cause symptoms and signs of root compression. In patients with congenital narrowing of the cervical spinal canal (less than 10 to 11 mm in anteroposterior diameter), rela- tively mild trauma or osteoarthritic changes may result in cord and root compression. Temporizing, using analgesic medications, and particu- larly immobilization of the neck (soft collar, traction) frequently relieves the symptoms. Failure of conservative therapy may require sur- gical measures (see discussion of cervical spondylosis, Chap. 43). Rheumatoid arthritis of the cervical spine, in its advanced form, may give rise to a number of acute and chronic spinal cord syndromes. The most serious is acute spinal cord compression due to vertebral sublux- ation, particularly atlantoaxial subluxation with odontoid displacement. Thoracic outlet syndrome (cervical rib syndrome, anterior scalene syndrome) is a relatively infrequent condition seen often in women with drooping shoulders and poor muscle tone. The lower trunk of the brachial plexus, the subclavian vein, and the subclavian artery, together or in various combinations, are compressed in the lateral cervical region by a cervical rib, fascial bands, or possibly the anterior and medial sca- CHAPTER 11 / PAIN IN THE BACK, NECK, AND EXTREMITIES 107 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 107 lene muscles. Shoulder and usually medial arm pain, slight weakness and atrophy of muscles in an ulnar distribution, dusky discoloration of the hand and forearm, venous distention, and ischemic changes in the hand and arm are the usual clinical manifestations. Definitive diagnosis depends on EMG findings (see the Principles for details and treatment). Pain due to Diseases of Extremities Here one must distinguish pain due to rheumatoid and hypertrophic arthritis, atherosclerosis of iliac and femoral arteries, polymyalgia rheumatica, and reflex sympathetic dystrophy. The last named is of spe- cial neurologic interest (see below). Causalgia, one component of reflex sympathetic dystrophy, is described below and also with diseases of the peripheral nervous system (Chap. 45). Reflex Sympathetic Dystrophy This is the name applied to a group of painful states that commonly affect the arm and hand; the leg and foot are less frequently involved. The syndrome occurs in a number of clinical settings, so varied as to suggest more than one mechanism. These include shoulder injury, stroke, myocardial infarction (all of which result in immobilization of the arm), and partial traumatic interruption of peripheral nerves. Pain in the shoulder, arm, and hand, often causalgic (intense burning pain with allodynia), is accompanied by dystrophic and autonomic disturbances that may exceed sensory loss. When osteoporosis develops in the fore- arm and hand, the condition is called Sudeck’s atrophy. Causalgic-type pain is relieved temporarily by prolonged cooling. The pathogenesis is not fully understood. Since sympathetic block abolishes the pain in more than half the cases, ephaptic excitation of pain fibers by post- ganglionic sympathetic fibers is one of the postulated mechanisms. Another hypothesis attributes the pain to impaired function (hypersen- sitivity) of C fiber receptors. For a more detailed discussion of this topic, see Adams, Victor, and Ropper: Principles of Neurology, 6th ed, pp 194–223. ADDITIONAL READING Alexander E Jr, Kelly DL, Davis CH Jr, et al: Intact arch spondylolisthesis: A review of 50 cases and description of surgical treatment. J Neurosurg 63:840, 1985. Borenstein DG, Wiesel SW: Low Back Pain: Medical Diagnosis and Compre- hensive Management. Philadelphia, Saunders, 1989. Green RM, Ouriel K: Peripheral arterial disease, in Schwartz SI et al (eds): Prin- ciples of Surgery, 6th ed. New York, McGraw-Hill, 1994, pp 925–987. 108 PART II / CARDINAL MANIFESTATIONS OF NEUROLOGIC DISEASE 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 108 Long DM: Low back pain, in Johnson RT, Griffin JW (eds): Current Therapy in Neurologic Disease—5. St. Louis, Mosby, 1997, pp 71–76. Powell MC, Szypryt P, Wilson M, et al: Prevalence of lumbar disc degeneration observed by magnetic resonance in symptomless women. Lancet 2:1366, 1986. Schwartzman RJ, McLellan TL: Reflex sympathetic dystrophy: A review. Arch Neurol 44:555, 1987. Shannon N, Paul EA: L4/5, L5/S1 disc protrusions: Analysis of 323 cases oper- ated on over 12 years. J Neurol Neurosurg Psychiatry 42:804, 1979. Weinstein PR, Ehni G, Wilson CB: Lumbar Spondylosis, Diagnosis, Management and Surgical Treatment. Chicago, Year Book, 1977. Wilbourn AJ: The thoracic outlet syndrome is overdiagnosed. Arch Neurol 47:328, 1990. CHAPTER 11 / PAIN IN THE BACK, NECK, AND EXTREMITIES 109 4777 Victor Ch 11 p100-109 6/11/01 1:56 PM Page 109 110 12 Disorders of Smell and Taste The senses of smell and taste are unique in that they are responsive only to chemical stimuli. Clinically, these senses are subtly combined; many gustatory experiences are largely olfactory, and patients often think that they have lost their sense of taste when actually the loss is one of smell. While often a source of pleasure—we delight in certain aromas and savor our food—the senses of smell and taste seldom contribute in a fundamental way to health and survival (an exception might be the capacity to smell smoke). Nevertheless, disorders of these senses may be sources of complaint, and they may point to the presence of intracra- nial or systemic disease. OLFACTORY SENSE Clinical Disorders of Smell Anosmia Loss of the sense of smell is a frequent occurrence, but only if bilateral is it appreciated by the patient. Olfaction is tested by block- ing one nostril and then the other and asking the patient to sniff nonir- ritating substances, such as coffee, tobacco, vanilla, and perfume. If the subject can detect and describe (but not necessarily identify) these odors, the olfactory nerves are intact. Commercial scratch-and-sniff test kits are available. Numerous conditions and nasal disorders may cause anosmia or hyposmia by damaging the ciliated receptor cells in the upper nasal mucosa. The most common are chronic rhinitis of infective or allergic type, heavy smoking, influenza, and atrophic rhinitis (leprosy, local radiation). Receptor cells may be congenitally absent, notably in albi- nos. Concussive head injury and particularly fractures of the ethmoid bone cause anosmia by shearing the delicate central processes of the olfactory receptor cells as they pass through the cribriform plate to the SECTION III DISORDERS OF THE SPECIAL SENSES 4777 Victor Ch 12 p110-113 6/11/01 1:57 PM Page 110 Copyright 1998 The McGraw-Hill Companies, Inc. Click Here for Terms of Use. olfactory bulbs. The anosmia may be unilateral or bilateral and is often permanent. Subarachnoid hemorrhage, chronic meningitis, and cranial surgery, in which the frontal lobes and olfactory bulbs are retracted from the ethmoid bone, may have the same effect. The olfactory bulb and tract (second olfactory neuron) may be com- pressed by a meningioma of the olfactory groove, in which case the optic nerve is often implicated as well. The association of unilateral anosmia and optic atrophy with a contralateral papilledema is known as the Foster-Kennedy syndrome. Rarely, a large aneurysm causes the same syndrome. Children with anterior meningoencephaloceles or hydrocephalus are usually anosmic, and some of them exhibit CSF rhi- norrhea as well. A considerable proportion of patients with multiple sclerosis and Parkinson disease are hyposmic or anosmic, and odor recognition may be reduced in patients with Huntington chorea and Alzheimer disease. An impaired capacity to discriminate between odors, the primary per- ceptual aspects of olfaction being intact, is a characteristic feature of the alcoholic form of Korsakoff psychosis. Presumably these disorders of olfaction are due to involvement of the higher-order olfactory systems in medial-temporal and diencephalic regions. Parosmia and dysosmia These terms refer to perversions of the sense of smell; they occur with partial injuries of the olfactory bulbs or local nasopharyngeal infections, such as ozena or empyema of the nasal sinuses. Parosmia of extreme degree, in which every article of food has an intolerably disagreeable odor (and taste), is sometimes a manifesta- tion of a depressive illness. Parosmia of minor degree is not necessar- ily abnormal since protracted exposure to unpleasant odors can later be reawakened by other olfactory stimuli (phantosmia). Olfactory hallucinations These are always of central origin. They are observed most often as the aura—the brief initial manifestation (lasting only seconds)—of seizures that originate in the mesial-temporal cortex (“uncinate seizures”). Gustatory hallucinations are sometimes con- joined. Persistent olfactory hallucinations accompanied by delusions signify a psychiatric disease, most frequently endogenous depression or schizophrenia. Rarely, hallucinations that occur during the alcohol withdrawal period are olfactory; these hallucinations may also occur in patients with senile dementia, but in such cases one needs always to consider the presence of an associated late-life depression. GUSTATORY SENSE There are four primary taste sensations: salty, sweet, bitter, and sour. The receptors are exquisitely sensitive taste buds distributed mainly over the surface of the tongue and to a lesser extent over the palate, pharynx, and larynx. Each receptor is preferentially but not solely sen- CHAPTER 12 / DISORDERS OF SMELL AND TASTE 111 4777 Victor Ch 12 p110-113 6/11/01 1:57 PM Page 111 [...]... to those of the examiner Perimetry and tangent screen testing is more accurate The patterns of visual field loss from lesions in different parts of the visual pathway are illustrated in Fig 1 3- 1 , and the common causes of these visual field defects are summarized in Table 1 3- 2 4777 Victor Ch 13 p11 4-1 21 6/11/01 1:57 PM Page 117 CHAPTER 13 / COMMON DISTURBANCES OF VISION 117 TABLE 1 3- 2 Lesions of the... and Ropper: Principles of Neurology, 6th ed, pp 237 –257 4777 Victor Ch 13 p11 4-1 21 6/11/01 1:57 PM Page 121 CHAPTER 13 / COMMON DISTURBANCES OF VISION 121 ADDITIONAL READING Chester EM: The Ocular Fundus in Systemic Disease Chicago, Year Book, 19 73 Hayreh SS: Anterior ischemic optic neuropathy Arch Neurol 38 :675, 1981 Lyon G, Adams RD, Kolodny EH: Neurology of Hereditary Metabolic Diseases of Children... if partial, affects high tones more than low tones; the opposite occurs in conduction deafness This is determined most accurately by the use of an audiometer and the construction of an audiogram, which is an essential procedure in any investigation of hearing loss 135 Copyright 1998 The McGraw-Hill Companies, Inc Click Here for Terms of Use 4777 Victor Ch 15 p 13 5-1 43 136 6/11/01 1:58 PM Page 136 PART. .. mitochondrial diseases of the nervous system—Kearns-Sayre syndrome (involving ocular muscles, corticospinal tracts, cerebellum, and myocardium), Refsum disease, Bassen-Kornzweig disease, Batten-Mayou lipid storage disease, and endocrine-hypothalamic disease (Laurence-Moon-Biedl syndrome) The finding of a “cherry-red spot” denotes one of the hereditary metabolic storage diseases (Tay-Sachs, Niemann-Pick) The entire... retention of visual pursuit and vestibuloocular movements (erroneously called apraxia of gaze) Parieto-occipital lesion: Loss of pursuit movements to side of lesion; loss of slow phase of optokinetic nystagmus to side of lesion and of fast phase contralaterally; retained voluntary, commanded, and vestibuloocular movements Midbrain periaqueductal lesion: Paralysis of vertical gaze, more often of upgaze... (“retrobulbar neuritis”), although later temporal or complete pallor of the disc becomes apparent Infarction of the nerve head can also give the appearance of papilledema, but it too is associated with loss of 4777 Victor Ch 13 p11 4-1 21 120 6/11/01 1:57 PM Page 120 PART II / CARDINAL MANIFESTATIONS OF NEUROLOGIC DISEASE TABLE 1 3- 3 Common Clinical Types of Visual Loss Clinical problem Etiology Acute (minutes to... Clinical review of olfaction Am J Otolaryngol 14:227, 19 93 Pryse-Phillips W: Disturbances in the sense of smell in psychiatric patients Proc R Soc Med 68:26, 1975 Schiffman SS: Taste and smell in disease New Engl J Med 30 8:1275, 133 7, 19 83 4777 Victor Ch 13 p11 4-1 21 13 6/11/01 1:57 PM Page 114 Common Disturbances of Vision The diverse composition of the eye, containing epithelial, vascular, connective, muscular,... permission, from DG Cogan, Neurology of the Ocular Muscles, 2nd ed, Springfield, IL, Charles C Thomas, 1956.) 4777 Victor Ch 14 p12 2-1 34 6/11/01 1:58 PM Page 127 127 4777 Victor Ch 14 p12 2-1 34 128 6/11/01 1:58 PM Page 128 PART II / CARDINAL MANIFESTATIONS OF NEUROLOGIC DISEASE Abducens (sixth nerve) palsy: Paralysis of lateral rectus, causing medial deviation of the eye If this is partial, there is uncrossed... lesions high in the MLF, a loss of convergence is added With a lesion of the MLF near its origin, there may be involvement of 4777 Victor Ch 14 p12 2-1 34 6/11/01 1:58 PM Page 129 CHAPTER 14 / DISORDERS OF OCULAR MOVEMENT 129 the abducens nucleus, causing a homolateral paralysis of abduction combined with a failure of adduction on the opposite side (pontine gaze palsy) The one-and-a-half syndrome (Fisher) In... 1 4 -3 Parasympathetic stimulation constricts the pupil and sympathetic stimulation dilates it; i.e., parasympathetic and sympathetic paralyses have opposite effects Usually, lesions that interrupt the parasympathetic innervation of the pupil also interfere with accommodation This 4777 Victor Ch 14 p12 2-1 34 132 6/11/01 1:58 PM Page 132 PART II / CARDINAL MANIFESTATIONS OF NEUROLOGIC DISEASE FIG 1 4 -3 . dis- ease, and endocrine-hypothalamic disease (Laurence-Moon-Biedl syn- drome). The finding of a “cherry-red spot” denotes one of the hereditary metabolic storage diseases (Tay-Sachs, Niemann-Pick) Chap. 35 . The common clinical types of visual loss and their causes are sum- marized in Table 1 3- 3 . For a more detailed discussion of this topic, see Adams, Victor, and Ropper: Principles of Neurology, . patterns of visual field loss from lesions in different parts of the visual pathway are illustrated in Fig. 1 3- 1 , and the common causes of these visual field defects are sum- marized in Table 1 3- 2 . 116 PART