Encephalitis
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Nervous system
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Encephalitis
USMLE® Step 1 style questions USMLE
A 25-year-old man is brought to the emergency department by his partner following an episode of generalized convulsions. His partner reports that for the past 3 days, the patient has had a high fever and severe headache accompanied by nausea and vomiting. She also mentions that he started complaining of smell and taste changes. A few days ago, they came back from a trip to California in which they hiked and swam in lakes. Temperature is 38.9°C (102°F), pulse is 80/min, and blood pressure is 135/85 mmHg. On physical examination, the patient is confused and unresponsive. Pupils are equal and react sluggishly to light. Brudzinski sign is positive. A lumbar puncture is performed, and cerebrospinal fluid (CSF) analysis shows the following:
Cerebrospinal fluid Opening pressure 300 mm H2O Protein 130 mg/dL Glucose 20 mg/dL RBCs Numerous WBC count 1500/µL with polymorphonuclear predominance Neutrophils 80%
Gram stain of the CSF is negative. Head imaging results are nonspecific. Which of the following is the most likely causative organism?
Encephalitis is an acute inflammation of the brain. It can be caused by a viral, bacterial, or parasitic infection, or it can be a result of autoimmune disorders. Symptoms include fever, headache, nausea, vomiting, and fatigue. In some cases, encephalitis can lead to seizures, coma, and death.