225. The answer is a. (Ropper, pp 535-538.) The CSF in patients with normal-pressure hydrocephalus (NPH) is typically normal. Abnormalities in protein or cellularity should suggest an alternative diagnosis. The pressure of the CSF is also usually normal, although studies using long-term pressure monitoring in these patients have shown that they have periods of pressure elevation, often at night.
226. The answer is a. (Ropper, pp 1014-1023.) The most prominent characteristics of Alzheimer disease are neuronal loss, fibrillary tangles, loss of synapses, and amyloid (or neuritic) plaque formation. These histopathologic features are evident throughout the cerebral cortex, but the neurofibrillary tangles and neuronal loss are most prominent in the hippocampus and adjacent structures of the temporal lobe. The tangles and loss of synapses are most closely linked to the development of dementia. The cell loss may be so substantial that the patient develops marked compensatory enlargement of the ventricles, a condition called hydrocephalus ex vacuo.
227. The answer is d. (Ropper, pp 1014-1023.) The background posterior-dominant rhythm on the normal adult EEG is α activity at 8-to-12 Hz. With Alzheimer disease, the frequency of this rhythm may be slow, and the amount of time in which this rhythm is evident when the patient is lying relaxed with eyes closed may drop substantially. Periodic discharges in the form of sharp waves or spikes may develop during Creutzfeldt-Jakob disease. EEG is otherwise not especially helpful in distinguishing between the common causes of dementia.
228. The answer is b. (Ropper, pp 738-741.) Creutzfeldt-Jakob disease is a spongiform encephalopathy that produces dementia over the course of months. It is caused by the accumulation within the brain of an abnormal form of a normal protein that resists degradation by proteinases (a proteinase-resistant protein, prion protein). Myoclonic jerks—abrupt involuntary muscle contractions that may produce brief limb or facial movements—usually appear at some time in the course of this disease. These are often stimulus-sensitive, such that loud noises may provoke them. Similar movements may develop with Huntington disease, but these patients usually develop more constant and fluid limb movements, called chorea.
229. The answer is e. (Ropper, p 974.) Up to 90% or more of patients with trisomy 21 who die after age 30 have Alzheimer-type changes in the brain. The histopathologic features of Alzheimer disease may be evident in the person with Down syndrome at any age. That a hereditary form of Alzheimer disease was found linked to chromosome 21 raised hopes that a single mutation was the cause of the problem, but this was subsequently negated by the finding of hereditary forms of Alzheimer linked to chromosome 19 and sporadic Alzheimer associated with defects on neither of these chromosomes. Aside from persons with Down syndrome, Alzheimer disease only rarely develops in relatively young people.
230. The answer is d. (Ropper, pp 598-601.) NPH is a chronic, communicating form of hydrocephalus affecting elderly adults. The cause is unknown, but it may relate to prior episodes of trauma, infection, or subarachnoid hemorrhage. The clinical picture typically includes a triad of gait disturbance, dementia, and incontinence. The gait disorder, which may be difficult to distinguish from that of Parkinson disease, has been labeled an apraxic gait, as patients often have difficulty even lifting their feet off the floor, though they have no weakness and may perform motor tasks well with the legs when seated. CT or MRI in these patients usually shows enlargement of the temporal and frontal horns of the lateral ventricles out of proportion to the degree of cortical atrophy. There may also be a squaring off or blunted appearance of the frontal horns, and increased signal on T2-weighted images may be seen in the periventricular regions, consistent with the presence of fluid related to transependymal flow of CSF.
231. The answer is c. (Ropper, pp 1014-1023.) Alzheimer disease accounts for as much as 50% of the dementia in the general population confirmed at autopsy; Parkinson disease accounts for only about 1%. Only 80 years ago, neurosyphilis was the most common cause of dementia, but the introduction of penicillin reduced—though it did not eliminate—this spirochetal disease as a cause of dementia. As the population ages, the incidence and prevalence of Alzheimer disease are increasing. The dementia caused by Alzheimer disease is progressive over the course of years. Language disturbances may appear even before memory problems.
232. The answer is b. (Ropper, pp 599-600.) Up to 28% of patients who undergo ventriculoperitoneal shunting for NPH may suffer major complications, including subdural hematoma and infections. Subdural hematoma occurs because the reduction in intracranial pressure brought on by the reduction in CSF volume may cause the brain to pull away from the covering meninges, stretching and potentially rupturing the bridging veins.
233. The answer is a. (Ropper, p 1022.) Recognition of the fact that there is a cholinergic deficit in the brains of patients with Alzheimer disease has led to the development of acetylcholinesterase inhibitors designed to augment the cholinergic neurotransmitter system. Several different agents are available, including donepezil, galantamine, rivastigmine, and tacrine. Another drug with a different mechanism of action (memantine) is available. The effects are modest and act to slow cognitive decline as assessed by scales of cognitive function. There is still no cure for Alzheimer disease.
234. The answer is d. (Ropper, pp 1014-1023.) The major clinical features of Alzheimer disease are memory impairment, aphasia, apraxia, and neuropsychiatric impairment, including mood disturbances, delusions and hallucinations, personality changes, and behavior disturbances. The language disturbance may take the form of decreased fluency, dysnomia, and transcortical sensory aphasia, which refers to a reduction in the ability to understand complex linguistic structures. Repetition of verbal material is intact.
235. The answer is a. (Ropper, pp 424-425.) TGA refers to an episode of complete and reversible anterograde and retrograde memory loss lasting up to 24 hours. Patients have a persistent loss of memory for the time of the attack. During the episode, patients often appear bewildered and ask repeated questions. They retain personal identity (unlike characters suffering from transient amnesia in television shows) and can perform complex cognitive and motor tasks. TGA usually affects middle-aged or older men and often occurs in the setting of an emotional or other stressor, such as physical or sexual exertion. Although it shares features of transient ischemic attack, it is not associated with an increased risk of stroke. Nonetheless, a vascular evaluation is often appropriate, particularly in atypical or repeated cases and in the presence of risk factors for stroke. Most patients experience only a single episode. Some have stressed TGA’s similarity to migraine and hypothesized that it is related to migrainous ischemia of the medial temporal lobe structures.
236. The answer is e. (Ropper, pp 738-741.) The neurological symptoms occurring early in the course of Creutzfeldt-Jakob disease are often cerebellar or visual. Patients may have ataxia, clumsiness, or dysarthria, as well as diplopia, distorted vision, blurred vision, field defects, changes in color perception, and visual agnosia. Ultimately, cortical blindness may occur. The diagnosis may be supported by the finding of periodic sharp waves at a 1-to-2 Hz frequency on EEG and the finding of elevated protein 14-3-3 in CSF. The typical EEG pattern is found in up to 80% of patients at some point during the course of the illness. An MRI may show a pattern of increased T2 signal in the basal ganglia or other gray matter in many, but not all, cases.
237. The answer is i. (Ropper, pp 1003-1004.) Rett syndrome is a presumed X-linked genetic disorder that affects only girls; the homozygous version is thought to be fatal in male offspring. Usually the prenatal, perinatal, and early childhood development appear normal or nearly so, and then the girl undergoes rapid regression in cognitive status in early childhood, generally during the second year of life. There is loss of previously acquired language skills and effective eye contact, as well as purposeful hand movement. Stereotypic hand movements develop, usually taking the form of hand wringing, but also including tapping, patting, and at times hand-mouth movements. Seizures may also occur. Etiology is unknown, and there is no treatment.
238. The answer is h. (Ropper, pp 1027-1031.) Dementia is a prominent feature of Huntington disease. Apathy and depression occur commonly, and a schizophreniform illness may be the presenting manifestation at times. The dementia itself is subcortical, characterized by impairment in executive function and concentration, without the classic cortical features of Alzheimer disease, such as aphasia, apraxia, and amnesia.
239. The answer is k. (Ropper, pp 694-695.) General paresis is one of the manifestations of neurosyphilis. It is a chronic, often insidious meningoencephalitis that may be delayed up to 20 years after the original spirochetal infection. Clinically, it manifests as dementia, delusions, dysarthria, tremor, myoclonus, seizures, spasticity, and Argyll Robertson pupils. Diagnosis is based on the findings of a monocytic pleocytosis and positive serological tests for syphilis. When caught early and treated with penicillin, the prognosis for independence may be good in up to 40% of cases. Neurosyphilis may be asymptomatic. Its other symptomatic forms include meningitis, meningovascular syphilis causing infarcts, optic atrophy, tabes dorsalis (characterized by ataxia, urinary incontinence, and lightning pains caused by degeneration of the posterior spinal roots), and other forms of spinal syphilis.
240. The answer is g. (Ropper, pp 1103-1105.) Hypothyroidism in adults may present with headache, dementia, psychosis, and decreased consciousness. Neuromuscular findings are also common, and they include a myopathic weakness and a delay in the relaxation phase of reflexes (the hung-up reflex). Percussion of muscles may also cause a mounding of the muscle, called myoedema. Cerebellar ataxia may also occur. In severe cases, myxedema coma may occur, characterized by hypothermia, hypotension, and respiratory and metabolic disturbances. This requires emergent replacement of thyroid hormone.
241. The answer is b. (Ropper, pp 679-680.) Whipple disease is a rare multisystem disorder caused by T whippeli. Gastrointestinal complaints, such as steatorrhea, abdominal pain, and weight loss, reflect bowel infection. Central nervous system (CNS) infection, which may occur in the absence of gastrointestinal disease, may produce seizures, myoclonus, ataxia, supra-nuclear gaze disturbances, hypothalamic dysfunction, and dementia. Oculomasticatory myorhythmia (pendular convergence movements of the eyes in association with contractions of the masticatory muscles) may occur and is considered pathognomonic. At times, other muscles of the body may be involved. Diagnosis can be made by biopsy of the jejunum, though sometimes brain biopsy may be required and may show PAS-positive cells. Treatment with antibiotics may be curative, and, for this reason, the diagnosis is important to remember in unusual cases of dementia with movement disorders.
242. The answer is d. (Ropper, p 711.) Progressive multifocal leukoencephalopathy is a progressive leukoencephalopathy seen in immunocompromised patients, most notably those with AIDS. It is caused by the JC virus. The disease affects subcortical white matter, particularly in the occipital or parietal regions, leading to visual complaints or phenomena such as the alien hand syndrome, as in this patient. Cerebrospinal fluid is usually normal, and the lesions do not enhance on imaging studies. There are usually several foci of abnormality seen on MRI, which can be used reliably to make the diagnosis. In some cases, polymerase chain reaction detection of JC virus in the CSF can be used to make the diagnosis.
243. The answer is g. (Ropper, pp 719-721.) Herpes simplex virus (HSV) encephalitis is the most common form of sporadic encephalitis in the United States. Mortality approaches 70% without treatment, making early diagnosis crucial. Patients may present with acute onset of seizures or with a subacute course characterized by deficits referable to temporal lobe structures, such as amnesia, aphasia, or psychosis. Motor deficits also often occur. Headaches and fever are usually present. Eventually, declining levels of consciousness and even coma may occur, and patients are at risk of uncal herniation from massive swelling of the temporal lobes. Electroencephalography, MRI, and CSF analysis help to confirm the diagnosis. Only in rare cases is biopsy needed. Mortality may be reduced to 20% with acyclovir.
244. The answer is b. (Ropper, p 413.) The history and findings are most suggestive of a vascular dementia caused by multiple strokes. The best way to prevent further cognitive loss is to prevent strokes. Deep brain stimulation of subthalamic nucleus and carbidopa/levodopa are treatments for Parkinson disease. Ventriculoperitoneal shunting is a treatment for normal pressure hydrocephalus. Psychotherapy may improve a pseudodementia by treating underlying depression.