270. The answer is d. (Ropper, pp 874-896.) This is a typical history for MS. Multiple sclerosis is a progressive demyelinating disease of the central nervous system. Risk factors include a first-time demyelinating episode such as optic neuritis. Patients are more commonly in the 20-to-30 year age range, with a higher incidence in women. A transient ischemic attack is a brief period of brain ischemia causing neurological deficits that resolve within 24 hours. Patients who have a transient ischemic attack are at increased risk for stroke. A seizure is abnormal rhythmic electrical brain activity with a clinical correlation. There is nothing in the history to suggest that this patient had a seizure or a seizure predisposing factor. Seizure predisposing factors include previous seizure, brain trauma, brain hemorrhage, and encephalitis. An anaplastic astrocytoma is a malignant high-grade brain tumor. These often present with a seizure or hemorrhage. Risk factors include previous brain tumor. Parkinson disease is caused by a loss of dopaminergic neurons. It is characterized by asymmetric slowness, rigidity, and tremor. Risk factors include family history.
271. The answer is e. (Ropper, p 888.) Between 85% and 90% of patients with MS exhibit oligoclonal banding on electrophoretic studies of their CSF. This limited number of bands of excess immunoglobulin indicates that the species of IgG produced by the disease fall into a relatively small number of families. The proteins are not highly diverse, as would be the case with a polyclonal gammopathy. Other diseases such as syphilis, Lyme, and sub-acute sclerosis panencephalitis may also produce oligoclonal bands.
272. The answer is b. (Ropper, p 881.) The peculiar sensory phenomenon in which the patient feels an electrical sensation radiating down the spine when the neck is passively flexed is called Lhermitte sign and is believed to signify spinal cord disease. Patients with MS who have little more than optic atrophy and no evidence of spinal cord involvement may report the sensation. Dystonic posturing may also occur in patients with MS, but the posturing is usually spontaneous. A massive Babinski response may produce bladder evacuation and extensor plantar responses as well as involuntary leg withdrawal in these same patients. This type of reflex response is usually elicited by stimuli to the feet or legs rather than by manipulation of the neck or spine.
273. The answer is c. (Ropper, pp 874-896.) The IgG content of the CSF remains elevated, even between acute exacerbations of the MS. The IgG has a distinctive κ-light chain composition. This immunoglobulin typically accounts for more than 15% of the total protein content in the CSF of the patient with MS.
274. The answer is b. (Ropper, pp 874-896.) Corticosteroids are an appropriate treatment for a multiple sclerosis flare. They will reduce the length and severity of the flare in most cases, although they are not likely to change the long-term disease outcome. Interferon β-1B and glatiramer are appropriate treatments to reduce the frequency of multiple sclerosis flares; however, they are not useful for the acute treatment of a flare. Gabapentin is an anticonvulsant medication that is also useful for the treatment of neuropathic pain, such as burning and allodynia. It will not help a multiple sclerosis flare. Pramipexole is a dopamine agonist used to treat parkinsonism. It has no role in the treatment of multiple sclerosis.
275. The answer is c. (Ropper, pp 874-896.) Approximately 250,000 people in the United States carry the diagnosis of MS. Most of the affected persons live in northern states, but no state is exempt from reports of MS. Because there is no test to unequivocally establish the diagnosis, the exact number of active cases in the United States can be approximated only very roughly.
276. The answer is c. (Ropper, pp 874-896.) Optic neuritis occurs early and often in many patients with MS. This involves inflammation and demyelination of the optic nerve and slows conduction along the optic nerve. Components of the VER may be slowed or even absent. That an evoked response is disturbed is not proof that the patient has MS, as any problem that produces optic neuritis will disturb the VER. The Jolly test is an evoked response involving muscles. A peripheral nerve is shocked at 5-to-15 times per second, and the pattern of action potentials elicited in the muscle innervated is recorded. Sensory nerve conduction studies also involve an evoked response to a shock, with the resulting signal tracked in the sensory nerve stimulated. Muscle and peripheral nerve function is typically normal in patients with MS, unless they have an unrelated disease of the peripheral nervous system.
277. The answer is b. (Fauci, pp 1603-1604.) Gastric disturbances are a possible side effect of corticosteroid use. Ranitidine is an appropriate prophylactic treatment. Patients with high cholesterol should be given a heart-healthy diet. Neurological checks every hour, central venous line, and stat head CT for change in mental status are all things that should be done for unstable trauma patients with a cranial component.
278. The answer is d. (Fauci, p 2634.) Adrenoleukodystrophy, MS, SSPE, PML, and metachromatic leukodystrophy are all demyelinating diseases, but PML is the only one confidently linked to a virus. The specific strains of papovavirus most often implicated in PML are BK, JC, and SV40. The patients at risk for this often lethal demyelinating process are those with lymphomas, leukemias, and acquired immune deficiency syndrome (AIDS). Patients on immunosuppressants face substantially lower risk, but are at higher risk than the general population.
279. The answer is d. (Ropper, p 962.) Canavan disease may produce developmental regression at about 6 months of age. The infant develops extensor posturing and rigidity. Myoclonic seizures may develop. Underlying the disease is a defect in N-acetylaspartic acid metabolism. Elevated levels of this material can be detected in the blood and urine, but elevated levels in the brain establish the diagnosis. Changes in brain white matter are widespread and may result in a spongiform appearance. There is an increase in brain volume and weight.
280. The answer is c. (Ropper, pp 874-896.) This patient has a gradually progressive myelopathy. The differential diagnosis is broad, but MS is high on the list. A subset of patients with MS consists of middle-aged men with a progressive form of the disease. An MRI of the spinal cord could show MS plaques in the cord or other abnormalities intrinsic to the spinal cord parenchyma and could also exclude compressive lesions. Vascular malformations of the spinal cord can also be identified this way, although sometimes spinal angiography is required for definitive diagnosis. Cerebral angiography would not be helpful, except to evaluate for residual aneurysm, which is unlikely to be related to this patient’s problem. Spinal cord biopsy is unwarranted in this case, unless a specific indication is provided on neuroimaging. Visual evoked responses may be abnormal in MS, even without clinical evidence of disease, but would not account for the patient’s spastic paraparesis.
281. The answer is c. (Ropper, pp 874-896.) Patients with a multiple sclerosis often develop a spastic (upper motor neuron) bladder. There is little or no residual urine in the bladder after emptying because bladder contractility is good, but distensibility is poor. The bladder does not distend substantially because of corticospinal tract disease, which produces spasticity. The patient usually has urgency or incontinence.
282. The answer is b. (Ropper, pp 874-896.) Baclofen is an antispasmodic agent that may be used in MS. Additional agents that may be used include tizanidine or benzodiazepines. Cyclophosphamide is an immunosuppressive drug that may be used to treat MS, but would not be considered a symptomatic therapy.
283. The answer is d. (Ropper, pp 874-896.) Patients with demyelinating diseases often notice that their symptoms become worse in conditions of increased temperature. In fact, one old way of diagnosing MS called for the patient to be submerged in a tub of warm water; if the deficits worsened, this was considered a sign of MS. This heat sensitivity, also called Uhthoff phenomenon, explains why patients often feel worse in the summer or on taking hot showers. MS should be considered when seeing a patient who notices exercise-induced symptoms, because the increased heat that is generated by exercise may be enough to exacerbate the deficits.
284. The answer is a. (Ropper, pp 885-886.) Neuromyelitis optica produces signs and symptoms of bilateral optic neuritis in association with a transverse myelitis. The paraparesis, bladder and bowel dysfunction, and sensory deficit signal a transverse myelitis—that is, an inflammatory demyelinating lesion that transects much of the spinal cord. In some cases, the pathology shows a necrotizing process in the spinal cord. All of these problems may develop with MS, but cerebellar involvement, more scattered cerebral involvement, and a generally less circumscribed pattern of deficits are more likely. Adults are especially likely to develop a pattern more typical of relapsing-remitting MS after an initial episode of neuromyelitis optica. Children presenting with neuromyelitis optica may have no other signs or symptoms of demyelination.
285. The answer is d. (Ropper, pp 896-900.) Acute disseminated encephalomyelitis is often fatal. On examination of the brain, damage to small blood vessels and to perivascular tissues in the white matter of the cerebral hemispheres is extensive and coalescent. The diagnosis is suggested by the MRI or CT picture of rapidly evolving white matter damage associated with a high erythrocyte sedimentation rate (ESR) and a CSF under increased pressure with elevated red cell and white cell counts and elevated protein content. The CSF glucose content is usually normal.
286. The answer is f. (Ropper, pp 1070-1071.) The optic neuritis of MS produces enlargement of the physiologic blind spot, but rarely to the point where it impinges on central vision. When the blind spot extends into central vision, it is called a centrocecal scotoma. A young man presenting with this pattern of visual loss is much more likely to have Leber optic atrophy or another cause of optic atrophy (eg, tobacco-alcohol amblyopia, tertiary syphilis, or vitamin deficiencies) than to have multiple sclerosis. That other men in the family are similarly affected supports the diagnosis of the hereditary Leber optic atrophy. This condition is caused by one of several possible mutations in mitochondrial DNA.
287. The answer is h. (Ropper, pp 946-947.) Adrenal dysfunction in association with a progressive degenerative disease of the white matter suggests adrenoleukodystrophy. Some types are X-linked defects, and the fact that two brothers are affected in similar ways suggests that they have the X-linked form of adrenoleukodystrophy. X-linked adrenoleukodystrophy produces rapidly evolving brain damage in male infants or boys, with survival from onset of symptoms usually limited to 3 years. The underlying defect in this X-linked disorder is an ATP-binding transporter in the peroxisomal system responsible for long-chain fatty acid metabolism. Long-chain fatty acids accumulate in adrenal cortical and other cells. Pathophysiologically similar to, but otherwise distinct from, adrenoleukodystrophy is adrenomyeloneuropathy. It may develop in heterozygous women and usually involves less pronounced damage to the brain and more obvious damage to the spinal cord and peripheral nerves. Persons with adrenomyeloneuropathy routinely develop spastic paraparesis, problems with bladder and bowel control, and sensory disturbances in the legs.
288. The answer is e. (Ropper, pp 918-919.) Pelizaeus-Merzbacher disease is a demyelinating disorder that belongs to a group of degenerative diseases known as sudanophilic leukodystrophies. Leukodystrophy refers to the disturbance of white matter, and sudanophilic refers to the Sudan-staining characteristics of the involved white matter. Children with Pelizaeus-Merzbacher disease typically become symptomatic during the first months of life, but survival may extend into the third decade of life. Most affected persons are male.
289. The answer is b. (Ropper, pp 1097-1099.) Rapid correction of hyponatremia in an alcoholic may precipitate central pontine myelinolysis, a rapidly fatal, demyelinating disorder of the brainstem. With central pontine myelinolysis there is demyelination in the basis pontis. The destruction of myelin sheaths is usually quite symmetric and appears to begin in the median raphe. There is no inflammation associated with the demyelination, even though the changes occur acutely and progress rapidly. Death usually occurs within days or weeks of the first signs of neurological disease. Affected persons often have hypokalemia, hypochloremia, and hypomagnesemia as well as hyponatremia. Many have a low serum osmolality associated with a normal urine osmolality, findings consistent with the syndrome of inappropriate antidiuretic hormone. The signs of central pontine myelinolysis may be similar to those occurring with Wernicke encephalopathy (ie, disturbed ocular motor function, gait disturbances, and altered consciousness and cognition). That this patient did not have Wernicke encephalopathy was suggested by his having received thiamine before the administration of intravenous solutions, a measure usually sufficient to reduce or eliminate the risk of Wernicke encephalopathy.