GP CENTRAL NERVOUS SYSTEM CASES

Question 1

In a study of hypoglycemic shock, cellular changes in the brain are analyzed. One cell type in the hippocampus is noted to exhibit intense cytoplasmic eosinophilia, central chromatolysis, spheroidal swellings, and nuclear pyknosis. These changes appear 12 hours after blood glucose levels drop below 20 mg/dL. What is this cell type most likely to be?

Answer 1

Neurons

Question 2

A 75-year-old man has a history of transient attacks of loss of vision. The only abnormalities on physical examination are bruits over the carotids in the neck. Two days later he suddenly becomes hemiplegic and loses consciousness. He is rushed to the emergency room and a CT scan shows evidence of cerebral infarction. He is put on life support but dies 5 days later. At autopsy there is an area of necrosis and microscopically these lesions are noted to have increased numbers of cells distributed around the central zone of necrosis. Which of the following cell types is most likely to have a phagocytic function in these lesions?

Answer 2

Microglia

Question 3

A 49-year-old woman has had a severe headache for 2 days. On physical examination, she is afebrile and normotensive. Funduscopic examination shows papilledema on the right. One day later, she has right pupillary dilation and impaired ocular movement. She then becomes obtunded. Which of the following lesions best explains these findings?

Answer 3

Glioblastoma with edema

Question 4

A 16-year-old boy with no prior medical problems has complained of headaches for the past 9 months. There are no abnormal findings on physical examination. CT scan of the head shows enlargement of the lateral cerebral ventricles and third ventricle. A lumbar puncture is performed with normal opening pressure, and clear CSF is obtained, which has a slightly elevated protein, normal glucose, and no leukocytes.
Which of the following intracranial lesions is most likely to cause these findings?

Answer 4

Ependymoma

Question 5

A 61-year-old man has had worsening mental function with confusion for the past year, along with headaches. At first the headaches occurred in the morning, but for the past 3 months they have become continuous, along with nausea and blurred vision. On physical examination there is bilateral papilledema. A head CT scan shows enlargement of the entire ventricular system. Which of the following prior illnesses most likely led to his current problems?

Answer 5

Pneumococcal meningitis

Question 6

A 67-year-old woman has had new onset headaches with nausea for the past month. She now has a worsening headache with weakness in her right leg. On physical examination she has 4/5 motor strength involving her right leg. Extraocular muscle movements are intact. In which of the following locations is a neoplasm most likely to be found in this woman?

Answer 6

Left inferior frontal lobe

Question 7

An 81-year-old man with a history of poorly controlled atrial fibrillation suddenly collapses while watching television at home. Emergency medical services arrive promptly, but multiple attempts at cardioversion over 15 minutes are required to reestablish a stable pulse and blood pressure. Over the next day he develops bilateral papilledema, and an MRI of his brain shows an indistinct cortical gray-white junction and narrowing of ventricles. Which of the following intracranial abnormalities most likely developed in this man?

Answer 7

Cytotoxic edema

Question 8

A 45-year-old man develops a severe headache and fever over 2 days. On physical examination, he has nuchal rigidity and bilateral papilledema. His temperature is 38.5° C. A blood culture shows gram-positive cocci in chains, and Streptococcus pneumoniae is identified. The figure shows the representative gross appearance of a section of his brain. Based on this appearance, which of the following complications most likely resulted from this patient’s infection?

Answer 8

Herniation

Question 9

A 30-year-old woman, G3, P2, is in the third trimester of pregnancy. She has noted minimal fetal movement throughout the pregnancy. A fetal ultrasound scan shows normal amniotic fluid volume, normally implanted placenta, and the abnormality shown in the figure. Which of the following laboratory findings is most likely to be present in this woman?

Answer 9

Elevated serum alpha fetoprotein level

Question 10

A 22-year-old primigravida had a fetal screening ultrasound study at 18 weeks showing a single large cerebral ventricle and fused thalami. On physical examination at birth at 36 weeks’ gestation, the infant is small for gestational age and has multiple anomalies, including postaxial polydactyly of hands and feet, cyclopia, microcephaly, cleft lip and palate, and rocker-bottom feet. The infant dies 1 hour after birth. Which of the following CNS abnormalities best explains these findings?

Answer 10

Holoprosencephaly

Question 11

A 24-year-old man incurs head and neck trauma in a motor vehicle accident. He now has impaired pain and temperature sensation from the shoulders down to his feet, but proprioception and vibratory sense is preserved. He has motor weakness with muscle atrophy starting in his hands and extending to forearms and shoulders. An MRI of the cervical spinal cord shows a transverse slit-like cavity extending from the level of C2 to C7. What is the most likely diagnosis?

Answer 11

Syringomyelia

Question 12

A 15-year-old girl has had progressive difficulty speaking during the past 6 months. She becomes dizzy and falls frequently. She complains of headache and facial and neck pain. During the past month, she has had decreasing bladder and bowel control. On physical examination, there is loss of pain and temperature sensation over the nape of the neck, shoulders, and upper arms, but vibration and position sensation are preserved. She has muscle wasting in the lower neck and shoulders. MRI of the spinal cord shows cervical and thoracic enlargement with a CSF collection dilating the central canal. MRI of the brain shows gross findings similar to those shown in the figure. Which of the following is the most likely diagnosis?

Answer 12

Arnold-Chiari II malformation

Question 13

A neonate is born prematurely at 28 weeks’ gestation to a 22-year-old primigravida. The infant is initially stable, and a newborn physical examination shows no abnormalities. The infant becomes severely hypoxemic 24 hours later, and seizure activity is observed. There is poor neurologic development during infancy. CT scan of the head shows symmetrically enlarged cerebral ventricles at 8 months of age. Which of the following perinatal complications most likely produced these findings?

Answer 13

Germinal matrix hemorrhage

Question 14

A 21-year-old woman incurs a blow to her head from a fall while mountain biking. She then has loss of consciousness for 5 minutes. On examination her deep tendon reflexes are diminished. A head CT scan 6 hours later shows no abnormalities. She recovers over the next week, with no neurologic deficits, but cannot remember this event. During the next year she has irritability, headache, difficulty sleeping, trouble concentrating, and fatigue. Which of the following is the most likely consequence from her injury?

Answer 14

Concussion

Question 15

An 83-year-old woman slips in the bathtub in her home and falls backward, striking her head. She is taken to the emergency department, where examination shows a 3-cm reddish, slightly swollen area over the occiput. She is arousable but somnolent. There are no motor or sensory deficits. There is no papilledema. CT scan of the head is performed. Acute hemorrhage in which of the following locations is most likely to be seen?

Answer 15

Inferior frontal lobe

Question 16

A 19-year-old snowboarder wearing protective equipment consisting of a baseball cap, baggy shorts, and a flak jacket flew off a jump and hit a tree. He was initially unconscious, and then “came to” and wanted to try another run, but his friends thought it best to call for help. On the way to the emergency department, he became comatose. Physical examination now shows left papilledema. Skull radiographs show a linear fracture of the left temporoparietal region. This clinical picture is most consistent with which of the following lesions?

Answer 16

Middle meningeal artery laceration

Question 17

A 72-year-old woman trips and falls down the stairs. She does not lose consciousness. She develops a headache and confusion 30 hours later and is taken to the emergency department. On physical examination, she is conscious and has a scalp contusion on the occiput. What is the most likely location of an intracranial hemorrhage in this patient?

Answer 17

Subdural

Question 18

An 80-year-old resident of a nursing home is admitted to the hospital because of recent onset of fluctuating levels of consciousness with headache and confusion for the past 2 days. On physical examination, she is arousable, but disoriented and irritable. Vital signs include temperature of 36.9° C and blood pressure of 130/85 mm Hg. There is papilledema on the right. CT scan of the head shows a collection of blood in the subdural space on the right. Which of the following vascular lesions most likely produced these findings?

Answer 18

Tearing of the cerebral bridging veins

Question 19

A 22-year-old man is caught in a rip current off Cabo San Lucas. He becomes tired and overcome by the waves. Lifeguards get him to shore, but he has no pulse. Resuscitative measures over the next 20 minutes establish a pulse. However, he does not regain consciousness. A month later an electroencephalogram (EEG) shows no brain wave activity. Which of the following cells most likely predominated in the cerebral cortex at the time of this EEG?

Answer 19

Macrophages

Question 20

A 68-year-old woman with atrial fibrillation suddenly lost consciousness and fell to the ground. When she became arousable, she was unable to move her left arm and had difficulty speaking. On physical examination, her temperature was 37° C, pulse was 81/min, respirations were 18/min, and blood pressure was 135/85 mm Hg. The figure shows the representative gross appearance of her brain in radiologic orientation. An MRI 3 months later shows a cystic space. The development of such a lesion most likely resulted from which of the following conditions?

Answer 20

Embolic arterial occlusion

Question 21

A 79-year-old man with metabolic syndrome has had 6 episodes of sudden dysarthria, a feeling of weakness in his hand and dizziness in the past 3 months. These episodes usually last less than 1 hour, and then he feels fine. Today, he suddenly lost consciousness while walking to the bathroom in his house and fell to the floor. On regaining consciousness 4 minutes later, he was unable to move his right arm. Which of the following underlying lesions is most likely to be found in his brain?

Answer 21

Cerebral atherosclerosis

Question 22

A study is conducted to identify causes of neuronal loss in patients 18 to 90 years old who died in the hospital from a natural manner of death and who had autopsies performed. Subsequent microscopic examination of sections revealed red, shrunken neurons, decreased numbers of neurons, or absent neurons. The hippocampal pyramidal cells, the cerebellar Purkinje cells, and the superior parasagittal neocortical pyramidal cells are affected. What condition is most likely to be the major cause of neuronal loss in these patients?

Answer 22

Global hypoxia

Question 23

A 70-year-old woman had an episode 2 days earlier during which she lost consciousness for several minutes. On physical examination, there is 4/5 motor strength in the right upper extremity and decreased sensation to pinprick on the right arm and hand. There are bilateral carotid bruits. CT scan of the head shows no intracranial hemorrhage, but there is a slight midline shift; MRI of the brain shows edema near the
left internal capsule. A lumbar puncture is performed with normal opening pressure. Laboratory studies on 10 mL of clear, colorless CSF show two mononuclear WBCs/mm3, no RBCs, protein concentration of 40 mg/dL, and glucose concentration of 70 mg/dL. The serum glucose concentration is 95 mg/dL. Which of the following laboratory findings is most suggestive of the risk factor for her disease?

Answer 23

Hypercholesterolemia

Question 24

A 59-year-old woman had sudden loss of consciousness 4 months ago. On physical examination, she now has left hemiplegia. CT imaging shows a large, cystic space in the right parietal region. MR angiography shows occlusion of a peripheral cerebral artery branch at the gray-white junction near the lesion. What underlying disease process is this woman most likely to have?

Answer 24

Ischemic heart disease with left ventricular thrombosis

Question 25

A 39-year-old man presents with headache and altered mental status of 60 hours’ duration. On examination he is afebrile and normotensive and has a reduced level of consciousness with aphasia. Lumbar puncture is performed and the CSF obtained has a lymphocytic pleocytosis with modest protein elevation. An MRI of the brain shows focal hyperintense cortical lesions. A stereotaxic brain biopsy shows chronic inflammation with granulomas involving arterioles and venules. Which of the following therapeutic options is most appropriate for this man?

Answer 25

Immunosuppresives

Question 26

A 55-year-old man suddenly loses consciousness while driving his truck, but he is traveling at a slow speed and comes to a stop without a collision. Paramedics arrive but are unable to arouse him. On physical examination, there is bilateral papilledema. He has no spontaneous movements. The figure shows the gross appearance of the brain at autopsy. What
underlying condition is most likely to have resulted in this lesion?

Answer 26

Systemic hypertension

Question 27

A 72-year-old man has had poorly controlled hypertension for the past 20 years. Over the past day he has had a severe headache with nausea, followed by confusion, then convulsions. On examination he is afebrile, but his blood pressure is now 260/150 mm Hg. There is bilateral papilledema. Which of the following pathologic lesions is most likely to
have developed in his brain during the past day?

Answer 27

Arteriolar fibrinoid necrosis

Question 28

A 72-year-old man with diabetes mellitus has had stepwise cognitive decline for the past 5 years. On multiple occasions he has had an acute event, such as loss of consciousness or confusion, followed by worsening ability to perform activities of daily living. On physical examination, he has mild right hemiparesis, ataxia, and dysarthria. Which of the following
pathologic findings is most likely to be present and numerous in this man?

Answer 28

Lacunes

Question 29

An 86-year-old man has become progressively unable to live independently for the past 10 years, and he now requires assistance with bathing, dressing, toileting, feeding, and transfers in and out of chairs and bed. On physical examination, he has no motor or sensory deficits. He cannot give the current date or state where he is. Six months later, he suddenly becomes comatose and dies. At autopsy, there is a large superficial left parietal lobe hemorrhage. Histologic examination of the brain shows numerous neocortical neuritic plaques and neurofibrillary tangles. The peripheral cerebral arteries and the core of each plaque stain positively with Congo red. Which
of the following mechanisms is most likely responsible for his disease?

Answer 29

Aggregation of AB peptide

Question 30

A 50-year-old woman develops a sudden, severe headache and is taken to the emergency department. On examination, she has nuchal rigidity. Her blood pressure is 115/83 mm Hg. A lumbar puncture is done; the CSF shows numerous RBCs, no neutrophils, a few mononuclear cells, and a normal glucose level. The Gram stain result is negative. CT imaging shows subarachnoid hemorrhage at the base of the
brain. Which of the following vascular events has most likely occurred in this woman?

Answer 30

Rupture of an intracranial berry aneurysm

Question 31

A 45-year-old, previously healthy man has developed
headaches over the past month. There are no remarkable findings on physical examination. A cerebral MR angiogram shows a 7-mm saccular aneurysm at the trifurcation of the right middle cerebral artery. Which of the following is the
most likely complication from this lesion?

Answer 31

Subarachnoid hemorrhage

Question 32

A 25-year-old man has complained of headaches for the past 5 months. During that time, family members noticed that he was not as mentally sharp as he has been in the past, and that he has become more emotionally labile. Over a 2-week period, he has 4 generalized seizures. On physical examination, he now has no papilledema or movement disorder. CT scan
of the head shows a 2-cm mass in the right frontal lobe. A stereotactic biopsy specimen of this lesion shows only gliosis and evidence of recent and remote hemorrhage. The mass is removed, and histologic examination shows a conglomerate of various-sized tortuous vessels surrounded by gliosis. What is the most likely diagnosis?

Answer 32

Arteriovenous malformation

Question 33

A 19-year-old man has a sore throat followed a day
later by sudden onset of a severe headache. Physical examination shows mild pharyngitis and nuchal rigidity. His skin shows petechial hemorrhages. His temperature is 38.8° C, pulse is 98/min, respirations are 26/min, and blood pressure is 95/45 mm Hg. The figure shows the representative gross appearance of the surface of his brain. Which of the following infectious organisms is most likely to have produced
his disease?

Answer 33

Mycobacterium tuberculosis

Question 34

A 44-year-old woman who is an intravenous drug user
is admitted to the hospital with increasing headache and high fever for the past 24 hours. On physical examination, her temperature is 38.4° C, pulse is 85/min, respirations are 18/min, and blood pressure is 125/85 mm Hg. CT scan of the head shows no mass lesion or midline shift. A lumbar puncture is performed. The CSF shows 70,000 neutrophils/mm3, an increased protein concentration, and a decreased glucose level.
Which of the following infectious agents is most likely to produce these findings?

Answer 34

Staphylococcus aureus

Question 35

A 77-year-old man has been irritable for the past 2 days. He is otherwise healthy. On physical examination, he has a temperature of 39.1° C. Laboratory examination of the CSF from a lumbar puncture shows numerous neutrophils, slightly increased protein level, and decreased glucose concentration. On Gram staining of the CSF, which of the following is most
likely to be seen microscopically?

Answer 35

Gram positive cocci

Question 36

A 43-year-old woman has had a headache and fever for the past 2 weeks following a severe respiratory tract infection accompanying bronchiectasis. On physical examination, her temperature is 38.3° C. There is no papilledema. She has no loss of sensation or motor function, but there is decreased vision in the left half of her visual fields. CT scan of the head shows a sharply demarcated, 3-cm, ring-enhancing lesion in
the right occipital region. A lumbar puncture is done, and laboratory analysis of the CSF shows numerous leukocytes, increased protein, and normal glucose levels. What is the most likely diagnosis?

Answer 36

Cerebral abscess

Question 37

An 11-year-old boy has had pain in his right ear for
1 week and a severe headache for 1 day. On physical examination his temperature is 37.5° C. He has marked tenderness on palpation posterior to the right ear. Pus exudes from the right tympanic membrane, and Streptococcus pneumoniae is cultured. Which of the following intracranial complications is he most
likely to develop if untreated?

Answer 37

Epidural abscess

Question 38

A 4-year-old girl residing near Cape Town, South Africa has had worsening headache and irritability for the past week and now exhibits nausea, vomiting, and diminished responsiveness to verbal commands. On examination she has a temperature of 37.2° C. A tremor is observed in her extremities. Her eyes do not move laterally. A lumbar puncture is performed
and examination of the CSF shows 100 leukocytes/mm3, and 75% of them mononuclears. The CSF glucose is decreased, but the protein is markedly elevated. CT imaging with enhancement shows basilar meningeal thickening and a focal 2-cm mass involving the right cerebellar hemisphere. Which of the following infectious agents is most likely to produce these
findings?

Answer 38

Mycobacterium tuberculosis

Question 39

A 65-year-old man has been noted by his family to be
more apathetic, irritable, and withdrawn over the past year. He has worsening mental function. Neurologic examination shows a positive Romberg sign. His pupils constrict with near focusing but not with exposure to light. He has delusions of grandeur. He can remember only 1 of 3 objects after 5 minutes. CSF obtained from lumbar puncture shows a lymphocytic pleocytosis and elevated protein with increased IgG. Which of
the following organisms has most likely caused his illness?

Answer 39

Treponema pallidum

Question 40

A 26-year-old woman has headaches for 4 weeks
along with increasing malaise. Physical examination yields no remarkable findings. CT scan of the head shows no abnormalities. A lumbar puncture yields clear, colorless CSF with a normal opening pressure. Laboratory analysis of the CSF shows a normal glucose concentration and a minimally increased protein level. A few lymphocytes are present, but there are no neutrophils. A Gram stain and India ink preparation of the CSF are negative. Her condition gradually improves over the next 6 months. Serum serologic tests are most likely to show an elevated titer of antibodies to which of the following infectious agents

Answer 40

Echovirus

Question 41

A 25-year-old, previously healthy woman has acute
onset of confusion and disorientation followed by a generalized tonic-clonic seizure. On admission to the hospital, she is afebrile, and her blood pressure is 110/65 mm Hg. No papilledema is observed. Serum and urine drug screening results are negative. CT scan of the head shows a 3-cm recent hemorrhage in the left temporal lobe. A lumbar puncture is done, and the CSF shows only a few mononuclear cells and normal glucose and protein levels. Infection with which
of the following organisms is the most likely cause of her disease?

Answer 41

Herpes simplex virus

Question 42

A 33-year-old woman, G3, P2, had two previous pregnancies that resulted in normal term infants, but now she gives birth at 34 weeks’ gestation to a stillborn fetus. On examination, the fetus is observed to be hydropic. Autopsy of the fetus shows marked organomegaly, and the brain has extensive necrosis in a periventricular pattern, with focal calcifications. What congenital infection is most likely to produce these findings?

Answer 42

Cytomegalovirus

Question 43

A 14-year-old girl, living in Nigeria, who has received
poor prophylactic vaccines, develops mild diarrhea over 3 days, then has fever with neck stiffness and bilateral muscle weakness. On examination muscle tenderness is present, with 3/5 motor strength in all extremities. She has difficulty breathing that requires mechanical support of respiration. Over the next 6
months the pain disappears and some muscle strength returns. Which of the following nervous system structures has been affected most by her illness?

Answer 43

Anterior horns

Question 44

A 12-year-old boy develops fever, accompanied by occasional headaches, malaise, fatigue, and nausea a month after being bitten by a dog. One day later, he experiences episodes of rigidity, hallucinations, breath holding, and difficulty swallowing because of uncontrollable oral secretions. Dr. Louis Pasteur is consulted. He writes: “The death of this child
appearing to be inevitable, I decided, not without lively and sore anxiety, as may well be believed, to try … the method which I had found constantly successful with dogs. Consequently, 60 hours after the bites [the child] was inoculated under a fold of skin with half a syringeful of the spinal cord of a rabbit. In the following days, fresh inoculations were made. I thus made 13 inoculations.” The boy survives. Which of the following histologic findings in the brain of the dog is most likely to be present?

Answer 44

Negri bodies

Question 45

A 37-year-old man who is HIV-1-positive has had increasing memory problems for the past year. He is depressed. During the past 3 months, he has had increasing problems with motor function and is now unable to stand or walk. For the past 3 days, he has had fever, cough, and dyspnea. A bronchoalveolar lavage shows cysts of Pneumocystis jiroveci. MRI of
the brain shows diffuse cerebral atrophy; no focal lesions are identified. On microscopic examination of his brain, which of the following findings is most likely to be present?

Answer 45

Cortical microglial nodules

Question 46

A 52-year-old woman with leukemia undergoes chemotherapy. Two months later, she develops neurologic deficits with ataxia, motor weakness in the right arm, difficulty swallowing, and sensory changes in the left leg. MRI of the brain shows irregular areas of increased attenuation in white matter of the cerebral hemispheres and the cerebellum. A stereotaxic biopsy specimen shows perivascular chronic inflammation, marked gliosis, large reactive astrocytes with bizarre nuclei, and intranuclear inclusions within oligodendroglia. What virus most likely caused these findings?

Answer 46

JC Polyomavirus

Question 47

7 A 38-year-old man with chronic renal failure received
a kidney transplant. While being treated with cyclosporine, azathioprine, and high doses of corticosteroids, he began to experience headaches and became lethargic. On physical examination, he now has a fever and nuchal rigidity. A lumbar puncture is performed and the opening pressure is increased. A CSF cell count shows increased leukocytes. An India ink preparation shows the findings in the figure. Which of the following organisms is most likely infecting this man?

Answer 47

Cryptococcus neoformans

Question 48

A previously healthy 21-year-old man with a severe
headache for 5 days now has a new-onset seizure. Papilledema is noted on funduscopic examination. An MRI of the brain shows multiple 0.5- to 1.5-cm cystic periventricular and meningeal lesions. Which of the following infectious organisms is most likely to produce these findings?

Answer 48

Taenia solium

Question 49

A 20-year-old HIV-positive man has had a decreased
level of consciousness for the past week. He now experiences a generalized tonic-clonic seizure. On physical examination, his temperature is 37.6° C. MRI of the brain shows several 1- to 3-cm, ring-enhancing lesions in the cerebral gray matter bilaterally. A stereotaxic biopsy is performed. What pathologic
finding is most likely to be present on microscopic examination of the biopsy specimen?

Answer 49

Toxoplasma pseudocysts

Question 50

A 63-year-old previously healthy woman has become
more forgetful over a period of 6 weeks. One month later, she has difficulty ambulating and is unable to care for herself. On physical examination, she has myoclonus. She is afebrile. CT scan of the head shows minimal cerebral atrophy. An EEG shows low-amplitude, slow background activity with periodic complexes and occasional repetitive sharp waves with
intervals of 0.5 to 1 second. Which of the following histologic abnormalities is most likely to be found in her cerebral cortex?

Answer 50

Spongiform encephalopathy

Question 51

A 27-year-old woman had an episode of weakness
3 months ago, which she attributed to job stress and fatigue. The neurologic examination shows mild residual weakness, with 4/5 motor strength in the right lower extremity. A lumbar puncture is done, and laboratory examination of the CSF shows increased IgG levels with prominent oligoclonal bands. MRI of the brain shows small, scattered, 0.5-cm areas consistent with demyelination, most of which are located in
periventricular white matter. Which of the following complications is she most likely to develop?

Answer 51

Visual impairment

Question 52

A 28-year-old man states that 3 years ago he experienced paresthesias of his left arm and had difficulty walking, but these problems resolved. During the past year, he developed difficulty seeing from his left eye. Six months ago, he had difficulty writing with his right hand. On physical examination, there is decreased visual acuity on the left, no papilledema, and no retinal lesions. There is decreased motor
strength and decreased sensation in the right hand and forearm. MRI of the brain shows focal areas of increased signal intensity in periventricular white matter and in the left optic nerve. A lumbar puncture is performed. What finding is most likely to be present on examination of the CSF?

Answer 52

Oligoclonal bands

Question 53

A 74-year-old woman sustains blunt head trauma in
a motor vehicle accident. On admission to the hospital, she is conscious but disoriented. CT scan of the head shows a right temporal bone fracture and mild cerebral edema. Her blood alcohol level is 0.24 gm%. Two days later, laboratory studies show serum Na+, 109 mmol/L; K+, 3.9 mmol/L; Cl−, 82 mmol/L; CO2, 23 mmol/L; glucose, 73 mg/dL; and creatinine, 1 mg/dL. The hyponatremia is corrected over the next 2 hours
with intravenous fluid and electrolyte therapy and diuretics. She then rapidly becomes confused and exhibits limb weakness. No papilledema is seen on funduscopic examination. An MRI shows the finding in the figure. What complication has most likely occurred in this woman?

Answer 53

Central pontine myelinolysis

Question 54

An 8-year-old boy recovered uneventfully from a viral
upper respiratory infection 2 weeks ago, but now has the abrupt onset of lethargy and irritability. On neurologic examination he has diminished pupillary reflexes bilaterally along with ataxia of his extremities. CSF obtained by lumbar puncture microscopically shows small numbers of lymphocytes and erythrocytes. MRI shows multiple hyperintense lesions
at the gray-white junction. Which of the following pathogenic mechanisms is most likely causing this child’s brain lesions?

Answer 54

Demyelination

Question 55

A study is conducted of patients who had increased
phosphorylated tau and decreased Aβ peptide in their CSF 5 to 10 years prior to death at ages ranging from 55 to 80 years. At autopsy their brain weights are less than normal for age and body size. On gross examination, these brains show hydrocephalus ex vacuo and cortical atrophy but no focal lesions.
The figure shows the high power microscopic appearance of cerebral neocortex with Bielschowsky silver stain. Which of the following symptoms is most likely to be recorded in the medical histories of these patients?

Answer 55

Progressive memory loss

Question 56

A 68-year-old woman with a 7-year history of progressive dementia dies of bronchopneumonia. At autopsy, there is cerebral atrophy in a predominantly frontal and parietal lobe distribution. Microscopic examination of the brain shows numerous neuritic
plaques in the hippocampus, amygdala, and neocortex. Neurofibrillary tangles in the hippocampus contain tau protein. Congo red staining shows amyloid in the media of the small peripheral cerebral arteries. Which of the following genetic abnormalities is the most important factor in the development of her disease?

Answer 56

Presence of the e4 allele at the ApoE gene

Question 57

7 A 63-year-old man had increasing irritability over
3 years. He wandered about his neighborhood, complaining to the neighbors about everything. He had no memory loss and was always able to find his way home. The neighbors were pleased when he developed aphasia. On physical examination, there were no motor or sensory deficits and no gait disturbances or tremor. MRI of the brain showed bilateral marked temporal and frontal lobe gyral atrophy. He died of pneumonia 1 year later. At autopsy, the frontal cortex microscopically shows extensive neuronal loss, and some remaining
neurons show intracytoplasmic, faintly eosinophilic, rounded inclusions that stain immunohistochemically for tau protein. What is the most likely diagnosis?

Answer 57

Pick disease

Question 58

A 60-year-old woman had problems related to movement for 5 years. Physical examination showed cogwheel rigidity of limbs and a festinating gait, which she had difficulty initiating. Her face was expressionless. She was given levodopa/carbidopa, and her condition improved. Two years later, she had difficulty performing activities of daily living and showed marked cognitive decline. She died of aspiration
pneumonia. Autopsy findings include mild cerebral atrophy and loss of substantia nigra pigmentation. Microscopically, cortical neurons show spheroidal, intraneuronal, cytoplasmic, and eosinophilic inclusions. Immunohistochemical staining for which of the following proteins is most likely to be positive in these inclusions?

Answer 58

A-synuclein

Question 59

A 55-year-old man has had increasing difficulty with
initiation of voluntary movements and increasing inability to perform activities of daily living for 1 year. On physical examination, he has difficulty initiating movement, but he can keep moving if he follows someone walking ahead of him. He has an expressionless facies. The left side of the figure shows the gross appearance of the midbrain of this patient; on the right is a section through normal midbrain. What additional clinical feature is most closely associated with this abnormality?

Answer 59

Tremor at rest

Question 60

A 47-year-old woman from Venezuela has had difficulty performing activities of daily living for the past year. She is emotionally labile and often cries. She is disturbed and depressed by these developments because her mother and brother died 5 years after experiencing the same symptoms. On physical examination, she has choreiform movements of
her extremities. Cranial nerves are intact. She has no motor weakness and no sensory deficits. Her memory remains intact. Which of the following genetic abnormalities is most likely to be present in this woman?

Answer 60

Expansion of CAG repeats

Question 61

A 4-year-old girl developed clumsiness and difficulty
ambulating over 6 months. On physical examination, she showed difficulty with balance while walking, dysarthria, poor hand coordination, absent deep tendon reflexes, and a bilateral Babinski sign. Light touch and vibratory sensation were greatly diminished. There was no muscular weakness. Over the next 5 years, she developed congestive heart failure
from hypertrophic cardiomyopathy. She also had hyperglycemia. At autopsy, there was increased perinuclear iron deposition within cardiac myocytes. Which of the following genetic abnormalities with trinucleotide repeat expansions was most likely present in this patient?

Answer 61

GAA repeats in the frataxin gene

Question 62

A 36-year-old man who had been healthy all his life now has progressive, symmetric muscular weakness. A year ago, he noted weakness in the area of the head and neck, which caused difficulty with speech, eye movements, and swallowing. In the past year, the weakness in the upper and lower extremities has increased, and he can no longer stand, walk, or feed himself. His mental function remains intact. Which of the following cells is most likely being destroyed in this man?

Answer 62

Lower motor neuron

Question 63

A 12-year-old girl has had progressively diminishing
neurologic function over 3 years. She has difficulty with ambulation, decreased mental ability, seizures, and loss of control over bladder and bowel functions. An MRI of her brain shows atrophy, and the centrum semiovale and central white matter are shrunken. These findings correlate with widespread microscopic
myelin loss, but sub-cortical myelin is spared. Which of the following degenerative CNS diseases best explains her illness.

Answer 63

Metachromatic leukodystrophy

Question 64

A 49-year-old man develops an acute psychosis. He
has a lengthy history of chronic alcoholism. He has difficulty performing a finger-to-nose test, and there is paralysis of the lateral rectus muscles. A deficiency of which of the following nutrients is most likely to produce these findings?

Answer 64

Thiamine

Question 65

A 53-year-old man with a lengthy history of chronic
alcohol abuse has had an increasingly clouded sensorium over the past 2 days. On physical examination, he has a flapping tremor of his outstretched hands. MRI of the brain shows no
abnormalities. Microscopic examination of his brain would show increased numbers of neocortical and basal ganglia astrocytes with pale, swollen nuclei (Alzheimer type II cells). Which of the following laboratory findings in his blood is most likely to be associated with these findings?

Answer 65

Ammonia level of 100 umol/L

Question 66

A 55-year-old man has experienced headaches for the
first time in his life beginning 2 months ago. He comes to the emergency department following a generalized tonic-clonic seizure. On physical examination, he has weakness on the left side. An MRI of his brain shows a large, irregular, 6-cm mass in the centrum semiovale of the right cerebral hemisphere that extends across the corpus callosum. A stereotaxic biopsy of the mass is done and microscopically shows pleomorphic cells
positive for glial fibrillary acidic protein (GFAP). Molecular analysis shows abnormalities of TP53 and platelet-derived growth factor-alpha (PDGF-α). Which of the following neoplasms is he most likely to have?

Answer 66

Glioblastoma

Question 67

A 10-year-old boy has had persistent headaches for the
past 3 months. On physical examination, he is afebrile. He has an ataxic gait and dysdiadochokinesia. CT scan of the head shows a 4-cm cystic mass in the right cerebellar hemisphere. Cerebral lateral ventricles are enlarged. A lumbar puncture is done. The CSF protein concentration is elevated, but the glucose level is normal. Neurosurgery is performed, and the mass
is removed and sectioned. On gross examination, the mass is a cyst filled with gelatinous material. The cyst has a thin wall and a 1-cm mural nodule. Microscopically, the mass is composed of cells that stain positive for glial fibrillary acidic protein (GFAP) and have long, hairlike processes. What is the most likely diagnosis?

Answer 67

Astrocytoma

Question 68

A 40-year-old man has been experiencing headaches
for the past 6 months. He had a seizure 1 day ago. On physical examination, there are no remarkable findings. MRI of the brain shows a solitary, circumscribed 3-cm mass in the right parietal centrum semiovale. The mass has small cysts and areas of calcification and hemorrhage. Neurosurgery is performed, and the mass is removed. Microscopically, the mass consists of sheets of cells with round nuclei that have granular
chromatin. The cells have a moderate amount of clear cytoplasm, and they mark with GFAP by immunohistochemical staining. The patient receives adjuvant radiation and chemotherapy, and there is no recurrence. Which of the following molecular markers is most likely to be found in the cells of this mass?

Answer 68

1p and 19q co-deletions

Question 69

A 46-year-old woman has had increasing weakness and loss of sensation in the lower extremities for the past 5 months. She has been unable to walk without assistance for the past week. On physical examination, there is 4/5 motor strength in the right lower extremity and 3/5 motor strength in the left lower extremity. There is bilateral loss of sensation to light touch from the lateral midthigh distally. MRI of the spine shows a 1 × 4 cm lesion in the filum terminale. The mass is removed. Microscopically, the mass is composed of cuboidal cells around papillary cores in a myxoid background. Which of the following lesions was most likely present in this patient?

Answer 69

Ependymoma

Question 70

An 11-year-old girl has had increasing headaches upon
awakening for the past month. On examination,
papilledema is present bilaterally. An MRI of her brain reveals a 3-cm solid circumscribed mass within the fourth ventricle. There is third and lateral cerebral ventricular dilation. The mass is excised and microscopically shows perivascular pseudorosettes with round, regular tumor cells arranged around vessels. Which of the following neoplasms is she most likely to have?

Answer 70

Ependymoma

Question 71

A 5-year-old boy has complained of headaches for the
past week. His gait has become ataxic. After sudden onset of vomiting, he is brought to the emergency department, where he becomes comatose. On physical examination, he is afebrile. A lumbar puncture is done and cytologic examination of the CSF shows anaplastic cells with dark blue nuclei and scant
cytoplasm. An MRI is most likely to show a mass in which of the following locations?

Answer 71

Cerebellar vermis

Question 72

A 39-year-old HIV-positive man has received no anti-retroviral therapy. He has had left-sided weakness for the past month and experienced a generalized seizure a day ago. On physical examination, he is afebrile. CT scan of the head shows no intracranial hemorrhage, but there is a midline shift. MRI of the brain shows a 4-cm mass in the region of the putamen near the right internal capsule, a 3-cm mass in the right centrum semiovale, and a 1-cm mass near the splenium of the
corpus callosum. These masses are circumscribed and solid. CSF from a lumbar puncture shows an elevated protein concentration and a normal glucose level. Cytologic examination shows large cells with large nuclei and scant cytoplasm that mark with CD19, but not with GFAP or cytokeratin. What is the most likely diagnosis?

Answer 72

Large B-cell lymphoma

Question 73

A 45-year-old woman has had unilateral headaches on
the right for the past 5 months. Physical examination yields no remarkable findings. The representative gross appearance of the lesion seen on CT scan of the head is shown in the figure. The mass is surgically removed and microscopic examination shows elongated cells with pale, oblong nuclei and pink cytoplasm with occasional psammoma bodies. Cytogenetic analysis shows 22q-. What is the most likely diagnosis?

Answer 73

Meningioma

Question 74

A 76-year-old man has a single episode of grand mal
seizure. On physical examination, he is afebrile and normotensive. Motor strength is intact, and there is no loss of sensation. Cranial nerves are intact. His mental function is not diminished. There is a 1-cm, darkly pigmented skin lesion on the upper back. Brain MRI shows three solid, 1- to 3-cm mass lesions, without ring enhancement or surrounding edema, located at the gray-white junction in the right and left frontal lobes. The cerebral ventricles appear normal in size. What is the most likely diagnosis?

Answer 74

Metastatic carcinoma

Question 75

An 18-year-old student has had decreased vision in
her right eye for 6 months. On physical examination, there is papilledema on the right. She has 14 scattered, 2- to 5-cm flat, hyperpigmented skin lesions with irregular borders on the extremities and torso. CT scan of the head shows no intracranial hemorrhage and no edema or midline shift, but there is a mass in the region of the right optic nerve. An optic nerve glioma is excised. Eight months later, she returns for a follow-up examination, and a mass is palpated on the right wrist.
Histologic examination of the mass is most likely to show which of the following neoplasms?

Answer 75

Schwannoma

Question 76

A 41-year-old woman has had diminished hearing for
the past 4 months. On physical examination, she has decreased hearing on the left. Sound lateralizes to the right ear on the Weber tuning fork test. A head MRI shows a sharply circumscribed, 4-cm mass adjacent to the left pons that extends toward the left inferior cerebellar hemisphere. A smaller 1-cm lesion is in a similar location on the right. Family screening reveals a similarly affected 38-year-old sibling. An inheritedmutation involving which of the following genes is most likely to be present in this patient?

Answer 76

NF2

Question 77

A 20-year-old woman with learning difficulties had
flank pain for 1 week. Physical examination showed right costovertebral angle tenderness. Patches of leathery-appearing (shagreen patches) and hypopigmented (ash-leaf patches) skin were scattered over her body. There was a subungual nodule on her right index finger. Abdominal CT scan showed bilateral renal cysts and tumor masses. MRI of the brain showed
subependymal nodules and 1- to 4-cm cortical foci with loss of the gray-white distinction. CT scan of the chest showed a 3-cm mass involving the interventricular septum. Two years later, she now has sudden, severe headache. MRI now shows a nodule obstructing the cerebral aqueduct. Neurosurgery is performed, and a subependymal giant cell astrocytoma is removed. What is the most likely diagnosis?

Answer 77

Tuberous sclerosis

Question 78

A study of adults with cerebellar neoplasms reveals that some of them have an autosomal dominant inheritance pattern with von Hippel–Lindau disease. Their cerebellar tumors are cystic with a mural nodule. Molecular analysis of tumor cells shows increased amounts of hypoxia-inducible factor (HIF). The incidence of renal cell carcinomas is increased in
these persons. Which of the following paraneoplastic manifestations is most likely to be found in these adults?

Answer 78

Polycythemia