CNS PATHOLOGY — Past Paper OmpathStudy

CNS PATHOLOGY — Questions and Answers Complete review bank: 55 questions recovered from all 37 source pages. 1. A 25-year-old man falls while skateboarding and strikes the left side of his head against a concrete retaining wall. On physical examination only a minor scalp abrasion is present at the site of the impact, with minimal bleeding that stops in 3 minutes. He is initially alert following this accident, but then became unconscious 30 minutes later. A head CT scan reveals a convex, lens-shaped area of hemorrhage centered over the left parietal region. These events are most likely to be associated with damage to which of the following parts of the intracranial vasculature? A. Bridging veins B. Cavernous sinus C. Great vein of Galen D. Inferior cerebellar artery E. Middle meningeal artery F. Ophthalmic branch of external carotid artery Answer: E. This is an epidural hematoma with a blow to the temple that damages the middle meningeal artery along the temporal bone. Arterial bleeding results in a rapid accumulation of blood in the epidural space. The blood expands this space, bounded by suture lines, and compresses underlying brain. There is risk for herniation. Significant bleeds require neurosurgical intervention with evacuation. 2. A 70-year-old man has a 2 day history of worsening generalized headache and increasing obtundation. He now complains of stiffness in his neck. On physical examination vital signs include T 38.7°C, pulse 85/minute, respirations 23/minute, and blood pressure 130/85 mm Hg. A CBC reveals a WBC count of 16,850/microliter. Serum electrolytes include a glucose of 88 mg/dL. A lumbar puncture yields cloudy cerebrospinal fluid with a glucose of 32 mg/dL, protein 146 mg/dL, and cell count of 3800 WBCs (95% PMNs and 5 % mononuclears) and 122 RBCs. He receives antibiotic therapy and improves. Which of the following long-term complications is most likely to develop from this man's current disease? A. Cerebral infarction B. Cerebellar tonsillar herniation C. Encephalitis D. Hydrocephalus E. Subdural hematoma Answer: D. The scarring following the bacterial meningitis can lead to obstruction of CSF flow at the foramina of Luschka and Magendie with obstructive non-communicating hydrocephalus, or alternatively scarring at the arachnoid granulations to reduce CSF reabsorption and produce communicating hydrocephalus. 3. An enterprising home distiller is using a barley mash to produce his own alcohol. He drinks the product and over the next day develops headache and difficulty walking. He now has difficulty with vision. On funduscopic examination there is optic disk hyperemia. He is disoriented and has difficulty answering questions. Which of the following is most likely responsible for the toxic effects he is experiencing? A. Mercury B. Formic acid C. Lead D. Organophosphate E. Oxalic acid F. Acetaldehyde Answer: B. Methanol is metabolized to the toxic compounds formic acid and formaldehyde. The retina is damaged. Distillation of spirits is an art and requires expertise. One could treat methanol poisoning with ethanol and/or fomepizole which are competitive inhibitors because they are metabolized via the same alcohol dehydrogenase as methanol. In contrast, acute ethanol overdose can lead to CNS depression and death. Chronic ethanolism can lead to Wernicke disease, which may have an element of cranial nerve findings. Chronic ethanolism can lead to liver disease and hepatic encephalopathy. 4. A 73-year-old man is undergoing radical prostatectomy for prostatic adenocarcinoma. During this procedure the anesthesiologist reports a drop in blood pressure with hypotension that persists for 30 minutes despite intervention with pressor agents. Which of the following pathologic lesions is most likely to occur in his brain as a consequence of this prolonged hypotensive episode? A. Hydranencephaly B. Linear parasagittal infarction C. Lacunar infarcts of basal ganglia D. Parietal lobe hemorrhagic infarction E. Anterior pituitary necrosis Answer: B. The most sensitive areas of the brain to ischemia will be the 'watershed' areas between anterior and middle cerebral arterial circulations. The neurons, and the large pyramidal neurons in particular, are the most sensitive to hypoxic/hypoglycemic stress. 5. A 28-year-old man undergoes induction chemotherapy for acute myelogenous leukemia. A week later he becomes severely pancytopenic, with WBC count of 1320/microliter, Hgb 7.9 g/dL, and platelet count 72,000/microliter. Head CT scan shows a right parietal hemorrhage. MR imaging and angiography reveals a right middle cerebral arterial thrombosis with right parietal hemorrhagic infarction. Which of the following infectious agents is most likely to cause these findings? A. Herpes simplex virus B. Toxoplasma gondii C. Human immunodeficiency virus D. Cytomegalovirus E. Aspergillus flavus Answer: E. Aspergillus loves to invade blood vessels and produce thrombosis. Neutropenia is a risk for aspergillosis. The portal of en