Subtle twitching after a witnessed convulsion
A 62-year-old retired landscape architect hospitalized for 2 days for diverticulitis had a witnessed, 90-second generalized tonic-clonic convulsion that ceased after intravenous lorazepam. Seventy-five minutes later, he has not regained consciousness. Temperature is 36.9 C (98.4 F), blood pressure 138/82 mm Hg, and pulse 88/min. He is stuporous and withdraws non-purposefully to sternal pressure. Examination reveals conjugate leftward gaze deviation, episodic left eyelid fluttering, and subtle rhythmic twitching of the left oral commissure. Noncontrast head CT completed 20 minutes ago shows only remote right frontal encephalomalacia. Serum electrolytes, glucose, and venous lactate are normal. Which of the following is the most appropriate diagnostic test?
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B
Explanation
Clinical Pearl:
Failure to regain baseline consciousness within 30 to 60 minutes after a convulsive seizure, particularly when accompanied by subtle rhythmic motor signs such as eyelid fluttering or facial twitching, warrants urgent electroencephalography to identify continuous nonconvulsive electrographic seizure activity.
Explanation:
Prolonged coma exceeding 30 to 60 minutes following a convulsion, particularly with subtle stereotypic motor signs like conjugate gaze deviation and rhythmic facial twitching, strongly indicates ongoing electrographic seizure activity without prominent convulsions. Relevant neurocritical care guidelines recommend urgent continuous electroencephalography to promptly establish the diagnosis and monitor response to subsequent antiseizure therapy. Lumbar puncture with cerebrospinal fluid analysis is appropriate for suspected central nervous system infection, but this patient is afebrile with normal inflammatory markers and displays characteristic focal electrographic phenomena. Repeat noncontrast computed tomography of the head provides no added diagnostic value because an identical study completed 20 minutes earlier excluded acute hemorrhage and mass effect, and computed tomography cannot assess neuronal electrical function. Magnetic resonance angiography of the intracranial vessels evaluates suspected arterial occlusion, but acute large-vessel ischemia does not account for the witnessed generalized convulsion followed by episodic facial twitching. Comprehensive urine and serum toxicology screening is uninformative in an inpatient hospitalized for several days under observation whose acute neurological deficit is directly linked to an observed seizure.
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