a = new Array(288);
var f = "<FONT FACE=ARIAL SIZE=2>"
a[0] = ""
a[1] = f + "(A) Incorrect. Subdural hemorrhage usually results from tearing of the bridging veins beneath dura."
a[2] = f + "(B) Incorrect. The cavernous sinus surrounds the carotid siphon. Infection with inflammatin can produce cavernous sinus thrombosis. Venous bleeding from a sinus or vein would be slow and symptoms would develop over a longer period of time."
a[3] = f + "(C) Incorrect. Trauma usually does not affect the great vein of Galen, though this structure can occasionally undergo thrombosis."
a[4] = f + "(D) Incorrect. Subarachnoid hemorrhage usually results from hemorrhage from arteries at the base of the brain, and these arteries are not often affected by trauma."
a[5] = f + "(E) CORRECT. This is an epidural hematoma with a blow to the temple that damages the middle meningeal artery. Arterial bleeding results in a rapid accumulation of blood in the epidural space."
a[5.1] = f + "(F) Incorrect. Disruption of blood flow of external carotid arteries typically does not produce major problems, though lack of flow in the ophthalmic branch may lead to blindness."
a[6] = f + "(A) Incorrect. The inflammation from bacterial meningitis can lead to local vascular thrombosis and resultant infarction, but following resolution of the inflammation an ischemic event is unlikely to occur."
a[7] = f + "(B) Incorrect. The increased intracranial pressure from acute bacterial meningitis can result in herniation."
a[8] = f + "(C) Incorrect. The inflammation tends to remain localized to the meninges and may spread down the Pierre-Robin space around perforating vessels to involve the superficial cortex. Inflammation does not persist in the brain following resolution of the meningitis."
a[9] = f + "(D) CORRECT. The scarring following the bacterial meningitis can lead to obstruction of CSF flow at the foramina of Luschka and Magendie with obstructive hydrocephalus, or alternatively scarring at the arachnoid granulations to reduce CSF reabsorption."
a[10] = f + "(E) Incorrect. A subdural hematoma is a typical complication of traumatic injury, not bacterial meningitis."
a[11] = f + "(A) Incorrect. These findings suggest Huntington disease."
a[12] = f + "(B) Incorrect. These findings suggest injury."
a[13] = f + "(C) Incorrect. These findings are typical for Parkinson disease."
a[14] = f + "(D) Incorrect. These findings are typical for amyotrophic lateral sclerosis."
a[15] = f + "(E) CORRECT. Plaques, as well as neurofibrillary tangles, are typical for Alzheimer disease, the most common form of dementia."
a[16] = f + "(A) Incorrect. This is a consequence of ischemia-infarction in utero with loss of much cerebral cortex."
a[17] = f + "(B) CORRECT. The most sensitive areas of the brain to ischemia will be the 'watershed' areas between anterior and middle cerebral arterial circulations."
a[18] = f + "(C) Incorrect. Lacunar infarcts are typically a consequence of hypertensive cerebrovascular disease."
a[19] = f + "(D) Incorrect. Hemorrhagic infarcts, particularly in the distribution of the middle cerebral artery, suggest an embolic etiology."
a[20] = f + "(E) Incorrect. Sheehan syndrome is more typically postpartum, as the pituitary has enlarged in pregnancy."
a[21] = f + "(A) Incorrect. Herpes simplex viral infection typically produces temporal lobe hemorrhagic lesions."
a[22] = f + "(B) Incorrect. Cerebral toxoplasmosis often produces multifocal areas of necrosis with abscess formation."
a[23] = f + "(C) Incorrect. HIV produces microglial nodules and a variety of miscellaneous lesions with microscopic encephalitis, but not thrombosis."
a[24] = f + "(D) Incorrect. CMV infection of the CNS is not typically associated with thrombosis or infarction."
a[25] = f + "(E) CORRECT. Aspergillus loves to invade blood vessels and produce thrombosis. Neutropenia is a risk for aspergillosis."
a[26] = f + "(A) CORRECT. A premature child, particularly in the gestational age range from 22 to 30 weeks, is at risk for germinal matrix hemorrhage, which often extends into the intraventricular region."
a[27] = f + "(B) Incorrect. This is an uncommon location for hemorrhage."
a[28] = f + "(C) Incorrect. Subdural hemorrhage typically occurs as a result of trauma in an adult. A subdural hematoma in a newborn is unlikely."
a[29] = f + "(D) Incorrect. Although small scalp hemorrhages are not common, they are not usually serious."
a[30] = f + "(E) Incorrect. Epidural hemorrhages from tear of a middle meningeal artery are usually the result of trauma to the temple in an adult."
a[31] = f + "(A) Incorrect. Cerebral edema is most marked in white matter. Enlargement of neuronal cell bodies is most marked with storage diseases."
a[32] = f + "(B) Incorrect. The thin layer of meninges accounts for little brain swelling."
a[33] = f + "(C) CORRECT. The greatest amount of salt and water increase with cerebral edema occurs within white matter."
a[34] = f + "(D) Incorrect. The tough connective tissue of the dura does not swell significantly."
a[35] = f + "(E) Incorrect. The ependymal lining does not swell significantly."
a[36] = f + "(A) Incorrect. The variable findings over several years are not typical for Parkinson disease, and she is too young."
a[37] = f + "(B) CORRECT. The findings point to multiple sclerosis, which is marked by plaques of demyelination. The perivascular lymphocytes suggest an inflammatory etiology, but the cause of this disease is unknown. MS can present with a host of variable neurologic problems because the plaques of demyelination can occur almost anywhere in the brain."
a[38] = f + "(C) Incorrect. She does not have Alzheimer disease."
a[39] = f + "(D) Incorrect. She does not have a non-Hodgkin lymphoma."
a[40] = f + "(E) Incorrect. She does not have HIV encephalopathy."
a[40.1] = f + "(F) Incorrect. These are findings with Huntington disease, which is marked by choreiform movements and dementia."
a[41] = f + "(A) CORRECT. Neural tube defects lead to abnormal development of the CNS, with subtle changes in morphology based upon changes in CSF flow, and the leak of fluid leads to a downward shift in CNS contents. The resultant cranial abnormalities include ventriculomegaly, lemon sign (due to flattened frontal bones), banana sign (due to effacement of the cisterna magna), and head measurements that are small for gestational age. With the lemon sign, the frontal bones are flattened (almost concave) so that the anterior skull is not as rounded. Lemons are a bit narrower on one end. The increased serum AFP is consistent with an open neural tube defect. Neural tube defects may be associated with maternal folate deficiency."
a[42] = f + "(B) Incorrect. Encephaloceles result from herniation of brain through a skull defect (usually occipital)."
a[43] = f + "(C) Incorrect. Arnold-Chiari II malformation can have a neural tube defect, but there is also a small posterior fossa with enlarged foramen magnum into which the cerebellar vermis and tonsils are displaced."
a[44] = f + "(D) Incorrect. Lissencephaly describes a 'smooth surfaced' brain without apparent gyration (which is normal under 20 weeks gestation)."
a[45] = f + "(E) Incorrect. This midline defect results from incomplete formation of the hemispheres with fused thalami. If the condition is 'alobar holoprosencephaly' then there is just single large ventricle. 'Semi-lobar holoprosencephaly' has partial bilateral hemisphere formation."
a[46] = f + "(A) Incorrect. Holoprosencephaly results from failure of formation of cerebral hemispheres, and there is just one big ventricle. The cranial cavity is, however, still intact."
a[47] = f + "(B) Incorrect. This autosomal recessive white matter storage disease of myelin metabolism results from a deficiency of aryl sulfatase A. Motor impairment begins in early childhood. White matter changes would not be seen in utero on ultrasound."
a[48] = f + "(C) CORRECT. This is a form of neural tube defect in which the occiput is not formed and herniation of brain occurs. Alpha fetoprotein is increased in amniotic fluid or maternal serum when there is an open neural tube defect."
a[49] = f + "(D) Incorrect. The germinal matrix, from which cellular migration occurs in fetal development, is present from about 22 weeks to 30 weeks gestation. In premature infants, it can be the site for hemorrhage into the ventricular system."
a[50] = f + "(E) Incorrect. Though there is a vertebral defect (failure of posterior arch fusion) with spina bifida occulta, there is no open defect to increase the AFP."
a[51] = f + "(A) Incorrect. Oligoclonal bands are most likely to appear in the CSF of a patient with multiple sclerosis with white matter plaques of demyelination, but JC papovavirus is not present."
a[52] = f + "(B) Incorrect. The elevation in Hgb A1C is a feature of poorly controlled diabetes mellitus that increases the risk for atherosclerotic cerebrovascular disease or for bacterial infections (meningitis, abscess) or mucormycosis (in cases with ketoacidosis)."
a[53] = f + "(C) CORRECT. The findings are those of progressive multifocal leukoencephalopathy (PML), which is a condition that can develop in immunocompromised patients, such as those with AIDS with markedly decreased CD4 cell count. PML is associated with papova (JC) virus infection."
a[54] = f + "(D) Incorrect. Such hyponatremia could lead to generalized edema and, if corrected too quickly, could lead to central pontine myelinolysis."
a[55] = f + "(E) Incorrect. A low HDL cholesterol is a risk factor for atherosclerosis, not demyelinating disease."
a[56] = f + "(A) Incorrect. In this setting, a hypertensive hemorrhage is more likely. The most common locations for hypertensive hemorrhages are the basal ganglia, pons, and cerebellum."
a[57] = f + "(B) Incorrect. A meningioma is slow growing and not often associated with sudden events."
a[58] = f + "(C) Incorrect. This condition is quite uncommon."
a[59] = f + "(D) Incorrect. Rapid correction of hyponatremia can result in CPM."
a[60] = f + "(E) CORRECT. The basal ganglia region is the typical location for hypertensive hemorrhages. The hemorrhage can extend to adjacent internal capsule."
a[61] = f + "(A) Incorrect. This finding is more typical of Huntington disease."
a[62] = f + "(B) Incorrect. This repetitive, to-and-fro eye movement can be the result of problems in multiple areas, including the vestibular apparatus, vestibulocerebellum, and brainstem."
a[63] = f + "(C) CORRECT. Cerebellar disease often manifests with ataxia. Patients with chronic alcoholism can develop anterior vermian atrophy. Truncal and gait ataxia suggests spinocerebellar involvement."
a[64] = f + "(D) Incorrect. This finding is more typical of Parkinson disease."
a[65] = f + "(E) Incorrect. This is more typical for lesions of the hippocampus."
a[66] = f + "(A) Incorrect. The LP did not reveal WBC's, and she was afebrile."
a[67] = f + "(B) CORRECT. About 1% of the population have such an aneurysm. Berry aneurysms are most likely to involve the Circle of Willis, so that rupture with bleeding occurs into the subarachnoid space at the base of the brain. The blood may cause irritation and spasm of adjacent arteries to cause worsening of symptoms from ischemia. Berry aneurysms can slowly enlarge but rupture suddenly."
a[68] = f + "(C) Incorrect. PML is a progressive illness in immunocompromised patient."
a[69] = f + "(D) Incorrect. Tay-Sachs is an inborn error of metabolism which produces disease in infancy and early childhood."
a[70] = f + "(E) Incorrect. Parkinson disease is a slowly progressive degenerative disease of older persons and is marked by a tremor at rest."
a[71] = f + "(A) CORRECT. Huntington disease (HD) is inherited in an autosomal dominant pattern. The gene is on chromosome 4, coding for a protein called huntingtin. Normally, there are 11 to 34 copies of the CAG repeat. There are more copies with HD; a greater number of copies correlates with earlier onset and greater severity of the disease (a genetic phenomenon called 'anticipation')."
a[72] = f + "(B) Incorrect. The substantia nigra of the midbrain shows loss of pigmented neurons with Parkinson disease, marked by a 'pill-rolling tremor' from imbalance of cholinergic and dopaminergic neuronal activity."
a[73] = f + "(C) Incorrect. The temporal lobe may demonstrate atrophy with Alzheimer disease. Marked 'knife-like' atrophy is a characteristic for Pick disease."
a[74] = f + "(D) Incorrect. The locus ceruleus is located in the brain stem and is not selectively affected by neurodegenerative diseases."
a[75] = f + "(E) Incorrect. Dorsal root ganglia contain neurons that serve a sensory function, not motor."
a[76] = f + "(A) CORRECT. This is degeneration of the portion of the median nerve distal to the injury. A complete transection (neurotmesis) will require proximal  axonal sprouting and growth down a preserved myelin sheath for nerve regrowth and reinnervation to occur."
a[77] = f + "(B) Incorrect. Fibrinoid necrosis is seen in small arteries in response to severe hypertension."
a[78] = f + "(C) Incorrect. Coagulative necrosis is a feature of ischemic injury."
a[79] = f + "(D) Incorrect. This is a feature seen in axons in the central nervous system with multiple sclerosis."
a[80] = f + "(E) Incorrect. Trauma itself does not lead to inflammation in peripheral nerve."
a[81] = f + "(A) Incorrect. A tear of the middle meningeal artery is typically associated with an epidural hemorrhage."
a[82] = f + "(B) Incorrect. Cavernous sinus thrombosis can occur from inflammation extending from the nasal sinuses, as with mucormycosis."
a[83] = f + "(C) Incorrect. The middle cerebral artery is unlikely to be affected by trauma; rather, it is the site for atherosclerotic or embolic disease or berry aneurysms."
a[84] = f + "(D) CORRECT. Falls in older persons, with some degree of cerebral atrophy can result in tearing of the bridging veins, which bare more exposed, and lead to development of a subdural hematoma. Such hematomas can develop over a variable length of time."
a[85] = f + "(E) Incorrect. The location of this vein means that it is unlikely to be affected by traumatic events; it can become thrombosed."
a[86] = f + "(A) CORRECT. Postmeningitic states may lead to communicating hydrocephalus from deficient reabsorption of CSF, or non-communicating hydrocephalus from blockage of foramina of Luschka and Magendie. Vaccination of infants for <I>Hemophilus influenzae</I> b may help prevent such occurrences."
a[87] = f + "(B) Incorrect. This is an uncommon condition that can lead to hydrocephalus that is non-communicating, but when it is congenital it should produce findings soon after birth, not likely to be delayed for months."
a[88] = f + "(C) Incorrect. The midline shift from the epidural may lead to occlusion of a foramen of Monro and hydrocephalus, but this is likely to show asymmetry. The time frame in this case is atypical."
a[89] = f + "(D) Incorrect. Subarachnoid hemorrhage (or the scarring that may follow) from a ruptured berry aneurysm at the base of the brain can block the flow of CSF. However, a berry aneurysm is unlikely to form and rupture in the pediatric age group."
a[90] = f + "(E) Incorrect. The midline shift from a rapidly growing neoplasm may lead to occlusion of a foramen of Monro and hydrocephalus, but this is likely to show asymmetry, and glioblastoma multiforme is typically seen in adults."
a[91] = f + "(A) Incorrect. The acute inflammation of bacterial meningitis does not promote vasospasm."
a[92] = f + "(B) Incorrect. Atherosclerosis leads to vascular narrowing from the buildup of atheromatous plaque."
a[93] = f + "(C) Incorrect. Severe hypertension can lead to hemorrhages, particularly in basal ganglia."
a[94] = f + "(D) Incorrect. Edema by itself does not produce vasospasm."
a[95] = f + "(E) CORRECT. The blood irritates the arteries. This effect is often delayed by several days following the initial hemorrhagic event. Berry aneurysms are located in the circle of Willis at the base of the brain, and rupture leads to extravasation of blood into the subarachnoid space. Her renal scan suggests a diagnosis of autosomal dominant polycystic kidney disease (ADPKD). About 10% of persons with ADPKD develop berry aneurysms."
a[96] = f + "(A) CORRECT. Granulation tissue with fibrosis is a typical reaction to a cerebral abscess. Collagen deposition around a ring enhancing lesion is typical for an abscess that organizes. The ring enhancement results from increased vascularity from capillary proliferation and disrupted blood-brain barrier. A common source for such a brain abscess is a lung infection."
a[97] = f + "(B) Incorrect. Aspergillus loves to invade blood vessels, leading to hemorrhage and infarction."
a[98] = f + "(C) Incorrect. PML does not have granulation tissue. PML is most likely to be seen in immunocompromised patients."
a[99] = f + "(D) Incorrect. Toxoplasmosis can produce ring-enhancing lesions, but they tend not to have granulation tissue. Toxoplasmosis is most likely to be seen in immunocompromised patients."
a[100] = f + "(E) Incorrect. Rabies does not produce such large lesions."
a[101] = f + "(A) Incorrect. ALS is a neurogenic form of myopathy with progressive muscular weakness."
a[102] = f + "(B) Incorrect. Alzheimer disease leads to progressive dementia with loss of mental ability."
a[103] = f + "(C) CORRECT. The tremor at rest is typical for Parkinson disease. A 'mask-like' facies is another manifestation of this degenerative disease resulting from loss of pigmented neurons in the substantia nigra."
a[104] = f + "(D) Incorrect. This storage disease results from lack of sphingomelinase and can lead to severe neurologic impairment in children. There is a mild adult form of the disease."
a[105] = f + "(E) Incorrect. This rare disease has scattered hamartomatous masses scattered in cortex. It is manifested with mental retardation."
a[106] = f + "(A) Incorrect. She does not have Parkinson disease."
a[107] = f + "(B) CORRECT. She has findings characteristic for Alzheimer disease. The neuritic plaques have amyloid cores, and patients may also have a congophilic angiopathy. Persons with the e4 allele of apoE are at increased risk for developing Alzheimer disease."
a[108] = f + "(C) Incorrect. Though she could have diffuse Lewy body disease, this is much less common than Alzheimer disease."
a[109] = f + "(D) Incorrect. She does not have multiple sclerosis."
a[110] = f + "(E) Incorrect. She does not have amyotrophic lateral sclerosis, in which upper and/or lower motor neurons are lost, characterized by loss of muscular movement, but preservation of intellect."
a[111] = f + "(A) CORRECT. Encephalitis with hemorrhagic lesions of the temporal lobe is typical for Herpes simplex virus infection. Affected persons do not have to be immunocompromised. (Note: when this patient was brought to the ER, the examining physician initially passed the problem off as a 'drug overdose' which was his default diagnosis for any mental problem in a young person, but the family refused to accept that and pressed him for further workup)."
a[112] = f + "(B) Incorrect. This organism is unlikely to involve the CNS, but remain limited to the lungs."
a[113] = f + "(C) Incorrect. This organism may rarely produce a granulomatous meningitis."
a[114] = f + "(D) Incorrect. This organism is most likely to produce a meningitis in children, and there is a neutrophilic exudate with increased PMNs in the CSF."
a[115] = f + "(E) Incorrect. This organism is most likely to produce an acute, severe meningitis, and there is a neutrophilic exudate with increased PMNs in the CSF."
a[116] = f + "(A) Incorrect. Cysticercosis produces focal lesions. These most often appear in adults who have ingested poorly cooked pork infected with <I>Taenia solium</I>."
a[117] = f + "(B) CORRECT. Remember TORCH for congenital infections. The 'T' for toxoplasmosis and the 'C' for cytomegalovirus are most likely to involve the CNS. The extent of necrosis and calcification with cytomegalovirus can be considerable. However, transplacental transmission of CMV does not produce significant disease in all cases."
a[118] = f + "(C) Incorrect. Poliovirus is most often contracted in childhood. The virus destroys motor neurons of cranial nerve nuclei and anterior horns of the spinal cord, leading to paralysis."
a[119] = f + "(D) Incorrect. <I>Candida</I> would be very rare as a congenital infection."
a[120] = f + "(E) Incorrect. Interstitial keratitis of the cornea can occur, and meningo-vascular syphilis is uncommon."
a[120.1] = f + "(F) Incorrect. Group B streptococcus is most likely to affect term infants and manifest soon after delivery. There is often generalized sepsis not limited to the CNS."
a[121] = f + "(A) Incorrect. The lesions of MS are plaques of demyelination involving white matter anywhere in brain and spinal cord."
a[122] = f + "(B) Incorrect. The substantia nigra of the midbrain is affected in Parkinson disease."
a[123] = f + "(C) Incorrect. ALS can involve the upper motor neurons as well as the lower motor neurons of spinal cord and is one cause for neurogenic muscular atrophy."
a[124] = f + "(D) CORRECT. Wernicke disease can also lead to hemorrhage and/or loss of periaqueductal grey matter. The Wernicke-Korsakoff syndrome is seen with chronic alcoholism. The mechanism may have to do with thiamine deficiency. (Micronodular cirrhosis with alcoholism is a risk for hepatocellular carcinoma.)"
a[125] = f + "(E) Incorrect. Huntington disease would affect the caudate nucleus, producing atrophy."
a[126] = f + "(A) Incorrect. An epidural hematoma is classically associated with a 'lucid' interval following loss of consciousness."
a[127] = f + "(B) CORRECT. The continued presence of a subdural hematoma leads to the problems described, even if it is relatively small. The trauma led to a rupture of dural bridging veins. Venous bleeding may be slow, so that the hematoma accumulated over time. When the clot begins to organize, it may imbibe additional fluid and increase in size."
a[128] = f + "(C) Incorrect. Contusions are not likely to lead to a change in findings a month later."
a[129] = f + "(D) Incorrect. An auto accident is unlikely to lead to just a subarachnoid hemorrhage."
a[130] = f + "(E) Incorrect. This is unlikely to be the only finding with trauma."
a[131] = f + "(A) CORRECT. The course is progressive. Bulbar involvement can lead to problems speaking and eating, with risk for aspiration. This disease often goes by the eponym of another baseball player, Lou Gehrig, who could not play first base anymore once the disease became advanced."
a[132] = f + "(B) Incorrect. This disease is characterized by development of a variety of neoplasms including neurofibromas and, sometimes, gliomas."
a[133] = f + "(C) Incorrect. MS does not often produce symmetrical findings. Moreover, the course of MS is quite variable."
a[134] = f + "(D) Incorrect. This is a pediatric disease, typically presenting as a 'floppy infant' with progressive muscular weakness. There is also loss of anterior horn cells with Werdnig-Hoffman disease."
a[135] = f + "(E) Incorrect. This is an acute process marked by ascending paralysis."
a[136] = f + "(A) Incorrect. The findings in this case do not point to a fungal infection that is more likely to be seen in immunosuppressed patients."
a[137] = f + "(B) Incorrect. The CSF findings with high WBC count and low glucose in this case do not point to a mycobacterial infection."
a[138] = f + "(C) Incorrect. This test is useful for detection of <I>Cryptococcus neoformans</I>, seen in immunocompomised patients most often."
a[139] = f + "(D) Incorrect. The findings do not point to a viral infection, which typically does not have such an abrupt onset or numerous WBCs."
a[140] = f + "(E) CORRECT. The findings point to an acute bacterial infection. The most likely organism at this age and under these circumstances is <I>Neisseria meningitidis</I>. The portal of infection may be upper respiratory tract, with an initial pharyngitis."
a[140.1] = f + "(F) Incorrect. A positive VDRL in the CSF is helpful for making the diagnosis of neurosyphilis, which is a late complication of tertiary syphilis, manifested by dementia and tabes dorsalis."
a[141] = f + "(A) Incorrect. The step-wise loss of function and the long period of non-progression are unusual for Alzheimer disease."
a[142] = f + "(B) Incorrect. Diffuse Lewy body disease can have movement problems similar to Parkinson disease and dementia that is similar to Alzheimer disease."
a[143] = f + "(C) Incorrect. Huntington disease is characterized by onset of choreoathetosis and dementia beginning at the latest by the 5th decade of life."
a[144] = f + "(D) Incorrect. Movement disorders are a prominent feature of Parkinson disease."
a[145] = f + "(E) CORRECT. The stepwise decline in mental function suggests a vascular event ('stroke') causing the decline. Multi-infarct dementia in some studies is second to Alzheimer disease as a cause for dementia. His enlarged heart suggests that there may be embolization as a cause for the vascular events."
a[146] = f + "(A) Incorrect. Sinus thrombosis is more likely to be a result of inflammation or coagulopathy."
a[147] = f + "(B) Incorrect. Cerebellar hemorrhages can be seen in cases of hypertension."
a[148] = f + "(C) CORRECT. The brain swelling leads to herniation, which damages small perforating vessels and results in Duret hemorrhages in the pons and midbrain. The hemispheric lesion that led to these findings is most likely a high grade glioma."
a[149] = f + "(D) Incorrect. Thrombosis of cerebral arteries is more likely to be a consequence of atherosclerotic disease or a coagulopathy."
a[150] = f + "(E) Incorrect. Subarachnoid hemorrhage is more likely to be a consequence of trauma or ruptured berry aneurysm."
a[151] = f + "(A) Incorrect. Ketoacidosis in patients with diabetes mellitus type I is a risk for rhinocerebral mucormycosis."
a[152] = f + "(B) CORRECT. Guillain-Barr&#233; syndrome, an acute idiopathic polyneuritis, is felt to be immunologic. About 75% of cases have a history of a preceding infection, including viral (cytomegalovirus) and bacterial (<I>Campylobacter jejuni</I>) agents."
a[153] = f + "(C) Incorrect. Bacterial septicemias may lead to cerebral abscesses."
a[154] = f + "(D) Incorrect. SLE can be associated with vasculitis and 'lupus cerebritis'."
a[155] = f + "(E) Incorrect. B12 deficiency can lead to posterior column degeneration in the spinal cord, with resultant neuropathy. If severe and prolonged, a dementia can result."
a[156] = f + "(A) CORRECT. She has a hypertensive hemorrhage, and the large collection of blood produces a mass effect with downward pressure to the posterior fossa to produce herniation."
a[157] = f + "(B) Incorrect. Parenchymal hemorrhages from hypertension do not usually extend into the ventricular system."
a[158] = f + "(C) Incorrect. An enlarging tumor mass with hemorrhage and necrosis, such as a glioblastoma, could increase intracranial pressure and produce herniation, but the mass this patient has is a hemorrhage."
a[159] = f + "(D) Incorrect. She has a basal ganglia hemorrhage, not an abscess."
a[160] = f + "(E) Incorrect. Watershed infarction is likely in the setting of hypotension, not hypertension."
a[161] = f + "(A) CORRECT. The findings point to a bacterial meningitis, and <I>H. influenzae</I>, <I>Neisseria meningitidis</I>, and <I>Streptococcus pneumoniae</I> are the most likely organisms to cause this finding in children. Vaccinations may alter the overall epidemiology and likelihood for infection."
a[162] = f + "(B) Incorrect. <I>C neoformans</I> is more likely to produce a meningitis in immunocompromised adults."
a[163] = f + "(C) Incorrect. Aspergillosis typically produces abscesses. Vascular invasion often produces significant hemorrhage in the lesions."
a[164] = f + "(D) Incorrect. Tuberculosis is typically associated with a chronic meningitis."
a[165] = f + "(E) Incorrect. CMV can produce a meningoencephalitis without a decreased glucose."
a[166] = f + "(A) Incorrect. The prognosis with a discrete, benign lesion such as a schwannoma is good."
a[167] = f + "(B) Incorrect. Neoplasms do not have remitting courses, but are progressive. Remissions and exacerbations are typical for multiple sclerosis. Sometimes the plaques are big enough to mimic a neoplasm."
a[168] = f + "(C) Incorrect. Schwannomas are typically sporadic, though some may occur in association with neurofibromatosis, particularly if bilateral."
a[169] = f + "(D) CORRECT. The findings are characteristic for schwannoma, called an acoustic neuroma when the 8th cranial nerve is involved. These are usually benign neoplasms. A solitary mass with no other lesions is unlikely to be part of neurofibromatosis."
a[170] = f + "(E) Incorrect. The AIDS-related neoplasm most often seen in the CNS is a high grade non-Hodgkin lymphoma."
a[171] = f + "(A) Incorrect. Anterior horn cell loss is a feature of amyotrophic lateral sclerosis and of poliomyelitis. Neurosyphilis may lead to neuronal loss in the brain, but not anterior horn cells."
a[172] = f + "(B) Incorrect. This is not a feature of neurosyphilis. Hemorrhagic encephalitis would be more typical of herpes simplex virus infection."
a[173] = f + "(C) Incorrect. Plaques of demyelination in white matter are characteristic for multiple sclerosis."
a[174] = f + "(D) Incorrect. Vacuolar myelopathy can be seen in AIDS with HIV infection."
a[175] = f + "(E) CORRECT. He has neurosyphilis. This helps to explain the term 'tabes dorsalis' in syphilis. <I>T. pallidum</I> infection leads to endarteritis in brain (as well as in the aorta). <I>T. pallidum</I> infection can also lead to chronic meningitis."
a[176] = f + "(A) CORRECT. These findings suggest a 'stroke' from cerebral infarction. Most brain infarcts result from thromboembolism. The most common source for emboli is the heart. Coronary atherosclerosis can result in myocardial infarction with overlying endocardial mural thrombosis. Such mural thrombi can embolize to the systemic circulation."
a[177] = f + "(B) Incorrect. Chronic meningitis may lead secondarily to obstructive hydrocephalus, not a focal cystic lesion."
a[178] = f + "(C) Incorrect. Focal lesions are not likely to be seen with Alzheimer disease, which is associated with plaques and tangles that are microscopic in size."
a[179] = f + "(D) Incorrect. The mass effect of a glioma is unlikely to produce episodic effects mimicking TIA's."
a[180] = f + "(E) Incorrect. Vasculitis is uncommon at this location and is not likely to produce a cystic infarct."
a[181] = f + "(A) Incorrect. Such hemorrhages are a feature of hypertension, not alcoholism."
a[182] = f + "(B) CORRECT. Persons with a history of alcohol abuse tend to fall and get superficial cerebral contusions. A fall backward with the head in motion striking the ground or an object on the occiput will produce a contrecoup mechanism of injury, with the force of the blow transmitted forward to the inferior frontal lobe and/or temporal tips."
a[183] = f + "(C) Incorrect. Pontine hemorrhages are most likely to occur with medial temporal lobe herniation (so-called 'Duret hemorrhages')."
a[184] = f + "(D) Incorrect. Hemorrhage into the thalamus is uncommon."
a[185] = f + "(E) Incorrect. Intraventricular hemorrhage is not likely to occur from a fall, but in an adult more likely to extend from an intraparenchymal hemorrhage."
a[186] = f + "(A) Incorrect. Such an increased protein suggests infection or neoplasia, but her findings suggest peripheral vascular disease and diabetes mellitus."
a[187] = f + "(B) Incorrect. Herpes viruses are not typically associated with peripheral neuropathy. Varicella zoster virus can be associated with a painful neuritis."
a[188] = f + "(C) Incorrect. Lead poisoning leading to a peripheral neuropathy is possible, but her findings point to a disease with associated marked peripheral vascular disease."
a[189] = f + "(D) Incorrect. Peripheral neuropathy and advanced atherosclerosis are not features of Down syndrome."
a[190] = f + "(E) CORRECT. Diabetic neuropathy is probably the most common form of peripheral neuropathy in the United States and Europe. She also has a 'diabetic foot' from severe peripheral vascular atherosclerosis, and the MI is consistent with severe occlusive coronary atherosclerosis."
a[191] = f + "(A) Incorrect. This is an open defect with herniated meninges. This could become infected."
a[192] = f + "(B) Incorrect. The absence of a cranial vault with lack of development of cerebral hemispheres is about as bad a defect as you can get."
a[193] = f + "(C) CORRECT. This is just a failure of the vertebral arches of bone to close over the cord. If it is 'spina bifida occulta' then nothing else protrudes. There may be an overlying dimple of skin to mark the spot, sometimes with a small tuft of hair."
a[194] = f + "(D) Incorrect. This is an open defect with protrusion of meninges and neural tissue."
a[195] = f + "(E) Incorrect. In this defect, often occipital, there is herniation of brain tissue out of the cranial cavity."
a[196] = f + "(A) Incorrect. As long as the berry aneurysm does not rupture, everyone will be happy."
a[197] = f + "(B) CORRECT. The location and radiographic changes suggest a glial neoplasm, most likely an oligodendroglioma."
a[198] = f + "(C) Incorrect. A meningioma is typically a peripheral discrete mass based on the dura."
a[199] = f + "(D) Incorrect. A schwannoma of the CNS is most often found arising from the 8th cranial nerve in the posterior fossa, and marked by hearing loss."
a[200] = f + "(E) Incorrect. An organizing abscess will have fibrosis, but not calcification."
a[200.1] = f + "(F) Incorrect. Infarcts in the brain have liquefactive necrosis, and when they resolve they leave a cystic area."
a[201] = f + "(A) Incorrect. The dementia of Alzheimer disease usually slowly progresses over 5 to 10 years."
a[202] = f + "(B) CORRECT. The incidence of the sporadic form of this disease is about 1 per 1,000,000. It is caused by an abnormal prion protein that induces a conformational change that leads to neuronal cell death and a rapidly progressive dementia. The formic acid pretreatment of the specimen will inactivate this protein."
a[203] = f + "(C) Incorrect. Though the total course of AIDS is not long, AIDS dementia is gradually progressive. There are no spongiform changes."
a[204] = f + "(D) Incorrect. Herpes presents with a prodrome of a few days and progresses to behavioral, motor, and mental changes."
a[205] = f + "(E) Incorrect. Lead poisoning produces both an encephalopathy and a neuropathy, along with anemia, renal abnormalities, and abdominal pain ('lead colic'). It does not tend to be rapidly progressive."
a[205.1] = f + "(F) Incorrect. Leigh disease is a form of mitochondrial encephalopathy that appears at a much younger age."
a[205.2] = f + "(G) Incorrect. PML is caused by the J-C papovavirus and produces neurologic decline over a longer period of time in persons who are immunocompromised."
a[205.3] = f + "(H) Incorrect. Rabies may follow the original animal bite by a variable time from 3 to 8 weeks and manifests with motor disturbances as well as irritability, agitation, hallucinations, and seizures."
a[206] = f + "(A) Incorrect. The Dandy-Walker malformation is characterized by an enlarged posterior cranial fossa with absent or rudimentary cerebellar vermis replaced by a midline cyst."
a[207] = f + "(B) Incorrect. In general, a bacterial meningitis or subarachnoid hemorrhage may organize to produce obstructive hydrocephalus, not viral infections, and posterior fossa anatomic abnormalities do not result from infections or hemorrhage."
a[208] = f + "(C) CORRECT. The findings are those of a Chiari type II malformation."
a[209] = f + "(D) Incorrect. Neural tube defects are more likely to occur with folate deficiency before and during pregnancy, but this does not explain the intracranial abnormalities."
a[210] = f + "(E) Incorrect. Werdnig-Hoffman disease is a form of spinal muscular atrophy similar to amyotrophic lateral sclerosis in adults, with loss of anterior horn cells, and leads to the appearance of a 'floppy infant'."
a[211] = f + "(A) Incorrect. There are no lymphatics in the brain, so cerebral edema is not a consequence of lymphatic obstruction."
a[212] = f + "(B) Incorrect. This is rare; a choroid plexus papilloma could possibly produce excess CSF."
a[213] = f + "(C) Incorrect. Neuronal storage diseases are more typical of children and do not typically manifest with cerebral edema."
a[214] = f + "(D) Incorrect. Cytotoxic cerebral edema typically ensues from diabetes insipidus. Persons with hyperosmolar coma tend to be dehydrated."
a[215] = f + "(E) CORRECT. The new vessels (neovascularization) at the margin of a tumor, particularly a rapidly-growing neoplasm such as a glioblastoma multiforme, or in the wall of an abscess, lack an effective blood-brain barrier, leading to cerebral edema."
a[216] = f + "(A) Incorrect. Though metastases could produce multiple lesions, he is young for this. Metastases are most common at the grey-white junction."
a[217] = f + "(B) Incorrect. HIV encephalopathy has microscopic findings, not gross lesions."
a[218] = f + "(C) Incorrect. Thromboemboli causing cerebral infarctions typically arise in the heart, but infarctions are not typically peripheral in subarachnoid space."
a[219] = f + "(D) CORRECT. This infection results when man becomes the accidental intermediate host for <I>Taenia solium</I> (pork tapeworm). The larvae may lodge in many organs but in the brain they are primarily found in the subarachnoid space and the cortex.They become encysted and the cysts within the subarachnoid space move around and can obstruct CSF flow leading to life threatening hydrocephalus."
a[220] = f + "(E) Incorrect. Hypertension is uncommon at his age. Hypertension leads to CNS hemorrhage."
a[221] = f + "(A) CORRECT. The findings suggest erythema migrans along with neurologic sequelae and pericarditis that result from Lyme disease with <I>Borrelia burgdorferi</I> infection transmitted by the bite of the deer tick (Ixodes sp.)."
a[222] = f + "(B) Incorrect. Mercury poisoning (organic mercury) is associated with ataxia."
a[223] = f + "(C) Incorrect. This set of findings are not typical for a drug rash or drug toxicity."
a[224] = f + "(D) Incorrect. There may be late neurologic complications of sexually transmitted diseases (syphilis, HIV) but years later, not weeks."
a[225] = f + "(E) Incorrect. The rash is not typical for SLE nor is the specific sequence of appearance of the findings. However, SLE can be associated with findings that mimic many other illnesses."
a[225.1] = f + "(F) Incorrect. Cocaine is a powerful vasoconstrictor. It may produce acute hemorrhages in the brain."
a[226] = f + "(A) Incorrect. Abscesses tend to have ring enhancement."
a[227] = f + "(B) Incorrect. Viral infections tend to produce diffuse meningoencephalitis, not a mass lesion."
a[228] = f + "(C) Incorrect. Multiple sclerosis can lead to formation of plaques that occasionally have a mass effect, but they are centered in white matter and typically occur in younger persons."
a[229] = f + "(D) Incorrect. Neuronal loss with gliosis, if focal, may represent an infarct, which over time would become cystic. Neurodegenerative diseases may also lead to this finding, but without a mass lesion."
a[230] = f + "(E) CORRECT. The location of the mass at the grey-white junction is typical for a metastasis. Smoking increases the risk for development of lung and renal carcinomas that are the most common sources for metastases to brain in males."
a[231] = f + "(A) Incorrect. A low platelet count can lead to hemorrhages anywhere in the CNS."
a[232] = f + "(B) Incorrect. Bacterial meningitis can lead to cerebral edema with herniation, but he would likely be febrile."
a[233] = f + "(C) Incorrect. A parietal fracture may disrupt the middle meningeal artery to produce an epidural hematoma."
a[234] = f + "(D) Incorrect. The loss of pigmented neurons suggests Parkinson disease, which is not associatd with cerebral edema and herniation."
a[235] = f + "(E) CORRECT. The location of the hemorrhages suggests Duret hemorrhages caused by disruption of perforating arteries from transtentorial herniation."
a[236] = f + "(A) Incorrect. Gliomas in adults tend to be located in the cerebral hemispheres above the tentorium."
a[237] = f + "(B) Incorrect. Choroid plexus papillomas are rare; they tend to be smaller than 4 cm."
a[238] = f + "(C) CORRECT. Ependymomas can arise from ependymal lining cells in ventricles. The mass effect can produce an obstructive hydrocephalus."
a[239] = f + "(D) Incorrect. Meningiomas arise beneath the dura peripherally, most often in a parasagittal or subfrontal location."
a[240] = f + "(E) Incorrect. Metastases tend to distribute to the cerebal cortex. Though they can appear anywhere, they are most often at the gray-white junction."
a[240.1] = f + "(F) Incorrect. Schwannomas most commonly arise in the eighth nerve (cerebellopontine angle)."
a[241] = f + "(A) Incorrect. The adenomatous polyposis coli gene is associated with colon carcinomas."
a[242] = f + "(B) Incorrect. CFTR is mutated to give rise to cystic fibrosis. The risk for neoplasia is not increased with cystic fibrosis."
a[243] = f + "(C) Incorrect. K-RAS is mutated in many human neoplasms, particularly carcinomas of epithelial origin."
a[244] = f + "(D) CORRECT. She has neurofibromatosis type 1, which is associated with development of neoplasms including neurofibromas, schwannomas, gliomas, and pheochromocytomas. NF-1 is a tumor suppressor gene. The lack of a family history suggests she has a spontaneous new mutation involving this gene."
a[245] = f + "(E) Incorrect. N-MYC is mutated and oncogenic in a variety of neoplasms, including neurobastoma of the adrenal."
a[245.1] = f + "(F) Incorrect. TP53 is a tumor suppressor gene that may undergo mutation to give rise to a variety of neoplasms, but not typically neurofibromas."
a[245.2] = f + "(G) Incorrect. RB is a tumor suppressor gene, and mutation can give rise to neoplasms such as retinoblastoma and osteosarcoma."
a[246] = f + "(A) Incorrect. Persons exposed to toxins affecting the CNS typically present with neurologic deficits that do not worsen over time."
a[247] = f + "(B) CORRECT. This rapidly ascending paralysis is Guillain-Barr&#233; syndrome, or acute idiopathic polyneuritis. About 75% of cases are associated with a history of a prior viral infection. An immunologic mechanism for this disease is suspected. In the case of <I>Campylobacter jejuni</I> infection, this involves molecular mimicry."
a[248] = f + "(C) Incorrect. Hypotension subjects neurons to anoxia, particularly in hippocampus, though watershed areas of cerebrum can be affected."
a[249] = f + "(D) Incorrect. Sepsis can produce a meningitis or abscess."
a[250] = f + "(E) Incorrect. Radiation therapy is given in measure doses that does not severely damage normal brain or spinal cord."
a[251] = f + "(A) Incorrect. An infarction is uncommon at this age. Vascular diseases with AIDS are uncommon."
a[252] = f + "(B) CORRECT. Toxoplasmosis occurs most commonly in immunocompromised patients, particularly those with AIDS, and most often involves the CNS to produce abscesses that are ring-enhancing."
a[253] = f + "(C) Incorrect. Contusions are located peripherally."
a[254] = f + "(D) Incorrect. Gliomas are not seen in associated with AIDS."
a[255] = f + "(E) Incorrect. Cysticercosis is a complication of eating uncooked pork containing <I>Taenia solium</I>. It is not an infection seen in immunocompromised persons."
a[256] = f + "(A) Incorrect. CPM occurs when there is rapid correction of hyponatremia."
a[257] = f + "(B) Incorrect. Venous thrombosis is uncommon. It is more likely to occur with inflammation than with trauma."
a[258] = f + "(C) Incorrect. Demyelination can occur with multiple sclerosis."
a[259] = f + "(D) CORRECT. The rotational forces applied to the brain as he was rolling along the ground produced stretching and tearing of axons within white matter tracts."
a[260] = f + "(E) Incorrect. Meningoencephalitis is more typical of infections, particularly viruses."
a[260.1] = f + "(F) Incorrect. Neuronal loss typically occurs with degenerative diseases such as Huntington disease or Parkinson disease."
a[261] = f + "(A) Incorrect. Metastases are unlikely to account for this rapid downhill course."
a[262] = f + "(B) CORRECT. Oops. Too rapid correction of hyponatremia can lead to CPM. He probably had a syndrome of inappropriate ADH with an oat cell carcinoma of the lung."
a[263] = f + "(C) Incorrect. Watershed infarctions are likely to be the result of severe hypotension, not electrolyte abnormalities."
a[264] = f + "(D) Incorrect. Basal ganglia hemorrhages are likely the result of hypertension, not electrolyte disturbances."
a[265] = f + "(E) Incorrect. Plaques of demyelination are seen with multiple sclerosis, which is not associated with electrolyte disturbances or neoplasia."
a[266] = f + "(A) Incorrect. Anterior horn cell loss is a feature of amyotrophic lateral sclerosis."
a[267] = f + "(B) Incorrect. These are findings typical for a cryptococcal meningitis, which is not acquired via an animal bite."
a[268] = f + "(C) CORRECT. The findings point to rabies infection following the animal bite, with transmission via infected saliva. In the U.S. skunks, raccoons, foxes, and bats are the most important hosts. Negri bodies are seen most prominently in hippocampus and cerebellum."
a[269] = f + "(D) Incorrect. Nodules with neutrophils are most often a feature of abscesses, such as those caused by bacterial infection."
a[270] = f + "(E) Incorrect. Spongiform encephalopathy is a feature of Creutzfeldt-Jakob disease, which presents as a rapidly progressive dementia."
a[271] = f + "(A) CORRECT. Leigh disease is a form of mitochondrial encephalopathy that appears at a young age. There is a genetic mutation in one of the genes coding for enzymes in the oxidative phosphorylation pathway."
a[272] = f + "(B) Incorrect. CMV can be a congenital infection and cause periventricular leukomalacia, but CMV is not likely to affect muscle tone or increase the plasma lactate."
a[273] = f + "(C) Incorrect. Small hemorrhages in the mammillary bodies and periacqueductal grey matter are seen with Wernicke disease, which is typically related to thiamine deficiency in adults, usually those with a history of chronic alcoholism."
a[274] = f + "(D) Incorrect. HSV typically produces temporal lobe hemorrhages. There may be a lymphocytic pleocytosis in the CSF."
a[275] = f + "(E) Incorrect. Leukodystrophies lead to demyelination and progressive decline in cognitive and motor function. However, the plasma lactate is unlikely to be increased."