328. A 65-year-old man was diagnosed with lung cancer 6 months ago. Over the past 2 months, he has had worsening severe proximal muscle weakness. He is most likely to have which of the following?
a. Dermatomyositis
b. Trichinosis
c. Multiple sclerosis (MS)
d. Progressive multifocal leukoencephalopathy (PML)
e. Myasthenia gravis
329. A 2-year-old male child has recently been diagnosed with the most frequent type of muscular dystrophy. The parents are highly educated people, but not in the medical field. They have many specific and detailed questions. Which abnormal gene is responsible for their child’s condition?
a. Glucose-6-phosphatase
b. Hexosaminidase B
c. Myosin
d. Dystrophin
e. Actin
330. A 67-year-old woman has noticed blurry vision and weakness over the past 4 months. Her symptoms are always worse toward the end of the day. She undergoes a neuromuscular evaluation, including nerve conduction study (NCS)/electromyography (EMG), which shows a decrementing response of compound muscle action potential to 3 Hz repetitive stimulation. She is positive for anti-AChR antibodies. Which of the following is the site of disease in this patient?
a. Anterior horn cell
b. Neuromuscular junction
c. Sensory ganglion
d. Parasympathetic ganglia
e. Sympathetic chain
331. A patient with amyotrophic lateral sclerosis develops progressive difficulty breathing. His cough becomes totally ineffective for clearing his airway, and he requires a tracheostomy. Facial muscle weakness and fasciculations are obvious at the time the tracheostomy is performed. Which of the following is the most appropriate treatment for this patient?
a. Atropine sulfate
b. Pyridostigmine
c. Edrophonium
d. Amantadine
e. Chest physical therapy
332. A 28-year-old woman has the clinical diagnosis of myopathy and undergoes a muscle biopsy for diagnosis. The pathology demonstrates an inflammatory muscle disease characterized by noncaseating granulomas. Which of the following may have caused her symptoms?
a. Cysticercosis
b. Tuberculosis
c. Sarcoidosis
d. Schistosomiasis
e. Carcinomatosis
333. A 62-year-old woman has limb discomfort and trouble getting off the toilet. She is unable to climb stairs and has noticed a rash on her face about her eyes. On examination, she is found to have weakness about the hip and shoulder girdle. Not only does she have a purplish-red discoloration of the skin about the eyes, but she also has erythematous discoloration over the finger joints and purplish nodules over the elbows and knees. Which of the following is the most likely diagnosis?
a. Systemic lupus erythematosus
b. Psoriasis
c. Myasthenia gravis
d. Dermatomyositis
e. Rheumatoid arthritis
334. The rash typically associated with dermatomyositis is characterized by which of the following?
a. Adenoma sebaceum
b. Shagreen patches
c. Target-shaped erythematous lesions on the extremities
d. A purplish discoloration around the eyes
e. Telangiectasias
335. A 32-year-old woman has several family members with Duchenne dystrophy. She has genetic testing and is known to be a carrier of the gene. A blood test may exhibit substantial elevations in her serum of which of the following?
a. Ammonia
b. Myoglobin
c. Phosphofructokinase
d. Creatine phosphokinase (CPK)
e. Hexosaminidase
336. When examining a young child with Duchenne dystrophy, you are asked by the parents if the condition is common. You would tell them that this disease affects how many of the following?
a. 1 in 3,000 infants
b. 1 in 3,000 male infants
c. 1 in 30,000 infants
d. 1 in 30,000 male infants
e. 1 in 50,000 infants
337. A 2-year-old male child has recently been diagnosed with muscular dystrophy. The parents are highly educated people, but not in the medical field. They have many specific and detailed questions. For a female child to have Duchenne dystrophy, she must have which of the following?
a. Turner syndrome (XO)
b. Klinefelter syndrome (XXY)
c. Two affected parents
d. An affected father
e. An affected brother
338. The spontaneous mutation rate for the dystrophin gene is presumed to be high for which of the following reasons?
a. Men with Duchenne dystrophy do not reproduce.
b. The incidence of Duchenne dystrophy is increasing.
c. Numerous birth defects occur in families with Duchenne dystrophy.
d. Men may become symptomatic after adolescence.
e. Genetic studies of eggs in human ovaries reveal an excess of abnormal dystrophin genes.
339. Intellectual function in children with Duchenne dystrophy can usually be characterized as which of the following?
a. Markedly impaired
b. Slightly impaired
c. Normal
d. Slightly better than that of the general population
e. Markedly superior to that of the general population
340. In patients with Duchenne dystrophy, which of the following is true?
a. Pseudohypertrophy routinely does not occur.
b. Pseudohypertrophy routinely is limited to the shoulder girdle.
c. Pseudohypertrophy routinely is limited to the hip girdle.
d. Pseudohypertrophy routinely is limited to the calf muscles.
e. Pseudohypertrophy routinely is limited to the thigh muscles.
341. A 37-year-old man has difficulty relaxing his grip on his golf club after putting. He also is excessively somnolent. Examination reveals early cataract development, testicular atrophy, and baldness. His family says that he has become increasingly stubborn and hostile over the past 3 years. His electrocardiogram (ECG) reveals a minor conduction defect. An electro-myogram (EMG) will probably reveal which of the following?
a. Repetitive discharges with minor stimulation
b. Polyphasic giant action potentials
c. Fasciculations
d. Fibrillations
e. Positive waves
342. A 75-year-old man has malaise and slowly progressive weight loss for the better part of 3 months. Laboratory tests reveal a hematocrit of 32%, an erythrocyte sedimentation rate (ESR) of 97 mm/h, and a white blood cell (WBC) count of 10,700 cells per μL. Serum CPK and thyroxine (T4) levels are normal. Which of the following is the most likely explanation for the patient’s complaints?
a. Polymyositis
b. Dermatomyositis
c. Polymyalgia rheumatica
d. Rheumatoid arthritis
e. Hyperthyroid myopathy
343. A 32-year-old man develops weakness in his hands over the course of 3 months. Further questioning reveals that he is also having trouble with swallowing. He occasionally slurs his words and has noticed progressive weakness in his cough over the preceding 4 weeks. The weakness is not substantially worse later in the day. He has no sensory symptoms associated with his weakness. Sexual function, bladder and bowel control, hearing, vision, and balance are all alleged to be unchanged. The examining physician discovers marked atrophy of the interosseous muscles of both hands. Deep tendon reflexes are hyperactive in the arms and the legs. Extensor plantar responses are present bilaterally. Rectal sphincter tone is normal. This patient’s illness characteristically produces electromyographic changes that include which of the following?
a. Fibrillations
b. Markedly slowed nerve conduction velocities
c. Impaired sensory nerve action potentials
d. H reflexes
e. No abnormalities
344. A biopsy is obtained from a clinically affected muscle in a person with several months of progressive weakness. The pathologist reports that there are numerous abnormally small muscle fibers intermingled with hypertrophied muscle fibers. The normal mosaic of muscle fiber types is disrupted. There is no significant inflammatory infiltrate. This pathologic description is most consistent with which of the following?
a. Disuse atrophy
b. Denervation atrophy
c. Muscular dystrophy
d. Polymyositis
e. Hypoxic damage
345. A 52-year-old left-handed woman says that she has a history of myasthenia gravis. When asked about details of the history, she says that she was weak. With further prompting, the patient becomes belligerent and says that she does not remember any further details. Which of the following is the most common manifestation of muscle weakness with myasthenia gravis?
a. Diaphragmatic weakness
b. Wristdrop
c. Footdrop
d. Ocular muscle weakness
e. Dysphagia
346. A patient with amyotrophic lateral sclerosis dies within 9 months of his initial evaluation. An autopsy is performed, but only the central nervous system (CNS) can be examined. Examination of the spinal cord would be expected to reveal degeneration of which of the following?
a. Dorsal root ganglia
b. Posterior columns
c. Spinothalamic tracts
d. Corticospinal tracts
e. Spinocerebellar tracts
347. The shortest life expectancy is associated with which clinical sign in amyotrophic lateral sclerosis?
a. Atrophy of the interossei
b. Atrophy of the gastrocnemius
c. Fasciculations in the lumbrical muscles
d. Atrophy of the pectoralis muscles
e. Fasciculations in the tongue
328. The answer is a. (Aminoff, pp 1144-1146.) Dermatomyositis occurs as a paraneoplastic syndrome in about 15% of cases overall. Among those older than age 40, the proportion of paraneoplastic cases increases to 40% for women and 66% for men. Tumors underlying dermatomyositis may develop in the lungs, ovaries, gastrointestinal tract, breasts, or other organs, but the CNS is generally not the site of a tumor associated with dermatomyositis. Because of the higher probability of malignancy in adults with dermatomyositis, patients diagnosed with this inflammatory disease should routinely undergo a variety of diagnostic studies, including rectal and breast examinations, periodic screens for occult blood in the stool, and hemograms. Sputum cytologies, full-body computed tomography (CT) scan, and urine cytologic studies are recommended by some physicians. Both PML and MS are strictly CNS diseases. Trichinosis is a parasitic disease that involves skeletal muscle and may produce substantial weakness, but it is not associated with any tumors.
329. The answer is d. (Ropper, pp 1366-1381.) Duchenne dystrophy has been incontrovertibly linked to the gene, located on the X chromosome, that makes dystrophin. The more profound the disturbance of this gene, the earlier the disease becomes symptomatic. The gene for dystrophin has single or multiple deletions in affected children. Women who are probable carriers of the defective gene can be checked for heterozygosity and given genetic counseling. Chorionic villus biopsy at 8-to-9 weeks can determine whether a fetus that is at risk for the deletion actually carries it.
330. The answer is b. (Ropper, pp 1405-1416.) Myasthenia gravis is a disease—or, more accurately, a collection of diseases—in which autoimmune damage occurs at the neuromuscular junction. The postsynaptic membrane is damaged in myasthenia gravis, and the acetylcholine receptor is the principal site of damage. A relative acetylcholine deficiency develops at the synapse because receptors are blocked or inefficient. Symptoms of myasthenia gravis range from slight ocular motor weakness to ventilatory failure.
331. The answer is e. (Ropper, pp 1059-1060.) This patient has a motor neuron disease. Pyridostigmine and edrophonium are useful in the evaluation and management of neuromuscular junction disease (eg, myasthenia gravis). Amantadine is useful in the management of Parkinson disease and MS, improving mobility in the former and reducing fatigue in the latter. Atropine might be of some use in this patient if he has excessive pulmonary secretions, but conscientious pulmonary toilet performed by an experienced physical therapist is much more likely to be beneficial.
332. The answer is c. (Aminoff, p 968.) Sarcoidosis is a poorly understood inflammatory disease that may cause neuropathy as well as myopathy. Multiple organs are usually involved with sarcoidosis, with hepatic or pulmonary disease often the most consistent finding. The noncaseating granulomas help to distinguish sarcoidosis from tuberculosis, a similar disease with an established infectious basis that usually produces caseating granulomas.
333. The answer is d. (Aminoff, pp 1144-1146.) This woman presents with proximal muscle weakness and pain and a heliotrope rash about her eyes. The term heliotrope refers to the lilac color of the periorbital rash characteristic of dermatomyositis. This rash surrounds both eyes and may extend onto the malar eminences, the eyelids, the bridge of the nose, and the forehead. It is usually associated with an erythematous rash across the knuckles and at the base of the nails and may be associated with flat-topped purplish nodules over the elbows and knees. Men with dermatomyositis are at higher than normal risk of having underlying malignancies. Psoriatic arthritis may be associated with reddish discoloration of the knuckles and muscle weakness, but the heliotrope rash would not be expected with this disorder. The age of onset for a psoriatic myopathy is also atypical. Similarly, the patient’s rashes are not suggestive of lupus erythematosus, although a myopathy may occur with this connective tissue disease as well.
334. The answer is d. (Aminoff, pp 1144-1146.) The violaceous, or purplish, discoloration developing around the eyes is called a heliotrope rash (after the flower that has similar coloring). These patients also have erythema over the knuckles. A target-shaped lesion on the limb suggests Lyme disease. Adenoma sebaceum and shagreen patches are skin changes typical of tuberous sclerosis. Telangiectasias over the malar eminences, conjunctivae, and ears occur with ataxia telangiectasia.
335. The answer is d. (Ropper, pp 1366-1370.) A high CPK in a woman with male relatives affected by Duchenne dystrophy indicates a high probability that she is a carrier of the abnormal dystrophin gene. A normal CPK, however, does not rule out the possibility that the woman is a carrier of Duchenne dystrophy. Even an asymptomatic carrier of the gene may have abnormalities in limb girdle muscles on biopsy.
336. The answer is b. (Ropper, pp 1366-1370.) Duchenne muscular dystrophy is a fairly common cause of childhood disability. Because it is X-linked, it is limited to boys. The disease is progressive, but the progression is over the course of years rather than weeks. Affected children rarely survive past adolescence. The incidence of the defect in male fetuses is greater than that in male infants because affected male fetuses have a higher rate of spontaneous abortion than do unaffected male fetuses in families carrying the abnormal gene.
337. The answer is a. (Ropper, pp 1366-1370.) Duchenne dystrophy may occur in the person with Turner syndrome if the inherited X chromosome carries the defective dystrophin gene. In the absence of a normal X chromosome, only the defective dystrophin will be produced. The person with Turner syndrome has only one X chromosome but is phenotypically female. Duchenne dystrophy may occur in girls with two X chromosomes, if translocations of material from the normal X chromosome inactivate or eliminate the normal dystrophin gene.
338. The answer is a. (Ropper, pp 1366-1370.) Despite the drain from the population of males carrying the abnormal gene, the incidence of Duchenne dystrophy is stable. Males often die before they reach sexual maturity or are too impaired after adolescence to mate. There are no changes in the ovaries of women bearing a child with Duchenne dystrophy to suggest that the mutation is arising de novo in the ovary. Women with apparently normal dystrophin genes do, however, give birth to affected sons.
339. The answer is b. (Ropper, pp 1366-1370.) Although profound mental retardation is not typical with Duchenne dystrophy, children with the disease characteristically perform more poorly than their unaffected siblings on objective cognitive tests. Persons with the Becker variant, the much milder form of the dystrophy that usually becomes symptomatic during adult life, may have no perceptible cognitive impairments. Women carrying the gene have normal cognitive abilities.
340. The answer is d. (Ropper, pp 1366-1370.) The calves are usually enlarged in the child with Duchenne dystrophy. Other clinical characteristics include a lordotic posture as weakness evolves in the hip girdle musculature. The gait becomes waddling before the child is unable to walk at all. Affected children invariably exhibit the Gower sign at some time in the evolution of their weakness: The child gets up from the floor by using his hands to walk up his legs and trunk to achieve an upright posture.
341. The answer is a. (Ropper, pp 1375-1377.) Men with myotonic dystrophy characteristically exhibit problems with relaxing their grip, hypersomnolence, premature baldness, testicular atrophy, and cataracts. The EMG pattern displayed by these patients is often referred to as the dive bomber pattern because of the characteristic sound produced when the evoked action potentials are heard. The cardiac defect that evolves in these persons usually requires pacemaker implantation to avoid sudden death. Psychiatric problems also develop in many patients with myotonic dystrophy, but their basis is unknown.
342. The answer is c. (Ropper, p 1360.) The markedly elevated sedimentation rate, anemia, weight loss, and malaise in a person of this age suggest polymyalgia rheumatica, although the same findings in someone 20 years younger could not be explained on the basis of this disorder. Fever may also be evident in the affected person. This constellation of symptoms also suggests an occult neoplasm or infection, and investigations should be conducted to reduce the likelihood of overlooking one of these diseases. Polymyalgia rheumatica is an arteritis of the elderly and is improbable in someone less than 60 years of age. The normal CPK activity markedly reduces the likelihood that this myalgia is the result of polymyositis or dermatomyositis. The new onset of rheumatoid arthritis at this age is also improbable. A hyperthyroid myopathy in the face of a normal T4 level is possible on the basis of an elevated T3 level, but it is also much less likely than polymyalgia rheumatica in this age group.
343. The answer is a. (Ropper, pp 1059-1060.) EMG and NCS are a way to establish anterior horn cell damage. The conduction times would be normal even with extensive motor neuron disease, but the pattern of spontaneous and evoked muscle potentials would be abnormal.
344. The answer is b. (Ropper, pp 43, 45.) Groups of muscle fibers are innervated by individual motor neurons. Characteristically, these muscle fibers will exhibit similar properties on histochemical staining with ATPase, phosphorylase, oxidases, and other markers of cellular characteristics. Adjoining groups of muscle fibers in skeletal muscle may have very different histochemical staining characteristics, but they are usually similar in size. With denervation, all the muscle fibers supplied by the damaged neuron or axon will atrophy. These atrophied fibers may recover if they are reinnervated by branches from adjacent neurons that have not been damaged.
345. The answer is d. (Ropper, pp 1405-1416.) More than 90% of patients with myasthenia gravis have some type of ocular motor weakness. This ranges from ophthalmoplegia to lid ptosis. Patients usually notice the lid weakness or complain of blurred vision as one of the first symptoms. More severe disease includes limb weakness, difficulty with swallowing, and respiratory difficulties. Patients usually report fatigue that increases as the day progresses.
346. The answer is d. (Ropper, p 1012.) This patient had amyotrophic lateral sclerosis (ALS). The disease causes loss of anterior horn cells (lower motor neurons) in the spinal cord and motor nuclei of the brainstem, loss of large motor neurons or Betz cells (upper motor neurons) in the frontal cortex, and degeneration of the corticospinal tract. The myelin sheath of the corticospinal tract axons secondarily degenerates. Often, ALS is called motor neuron disease precisely because it so dramatically targets the motor neurons. Damage to the motor system produces wasting, weakness, and spasticity. Signs of brainstem disease (diaphragmatic weakness, facial fasciculations) early in the course of disease indicate that the prognosis for survival beyond 1 year is poor.
347. The answer is e. (Ropper, p 1012.) In ALS, early involvement of musculature supplied by the cranial nerves has a much graver prognosis than early limb involvement. This may be a consequence of disturbed swallowing, with recurrent aspiration as a result, or disturbed ventilatory activity. Fasciculations of the tongue develop with deterioration of hypoglossal nuclei.