Nonconvulsive Status Epilepticus Masquerading as Delirium
An 78-year-old woman with hypertension and mild vascular cognitive impairment is admitted for 'confusion' after a fall. She is drowsy, intermittently muttering, and does not follow commands, fluctuating over 12 hours. She had a brief witnessed 'shake' of the left arm in the ED. Noncontrast head CT shows old lacunar infarcts and no acute hemorrhage. Metabolic panel is unremarkable except sodium 131. She is on no antiseizure medications. The admitting team diagnoses delirium and plans supportive care.
1. Why should nonconvulsive status epilepticus be considered, and what test is decisive?
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Fluctuating cognition with a witnessed focal motor event (left arm shaking) in an older adult with vascular disease is a red flag for nonconvulsive status epilepticus (NCSE) or a postictal state. The decisive test is urgent EEG - ideally continuous video-EEG - looking for rhythmic or periodic epileptiform discharges, especially in the context of altered mentation. Routine EEG may miss intermittent patterns, so continuous monitoring for at least 24 hours is preferred when suspicion is high. The presence of old infarcts provides a structural substrate. Delirium is a diagnosis of exclusion here; you must exclude NCSE before settling on it, because untreated NCSE carries substantial morbidity and mortality.
2. If EEG confirms NCSE, how does management differ from convulsive status epilepticus?
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The pharmacologic sequence is similar (benzodiazepines first, then second-line IV agents such as levetiracetam, valproate, or fosphenytoin, then anesthetic agents if refractory), but the urgency and endpoints differ: NCSE without coma is often treated less aggressively than convulsive SE because of the risks of intubation and sedation in an elderly patient, and because some forms (e.g., absence or late-onset) have different prognoses. In an elderly patient, watch for benzodiazepine-induced respiratory depression and falls; use the lowest effective doses. Treat precipitants (correct sodium cautiously - rapid correction risks osmotic demyelination; her 131 is mild and likely not causative). Continuous EEG guides titration and confirms cessation, since clinical exam is unreliable.
3. What else belongs in the differential, and how do the sodium and fall history shape your workup?
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Differential includes metabolic encephalopathy (sodium 131, though mild), infection (urinary tract, pneumonia), medication effects, postictal state after an unwitnessed seizure, and structural events (new stroke - consider MRI/DWI since CT can miss acute ischemia). The fall raises concern for subdural hematoma not seen on CT or for a seizure causing the fall. Workup: continuous EEG, MRI brain with DWI, urinalysis and cultures, medication review, and cautious sodium correction (limit to ~8–10 mEq/L per 24 hours). If NCSE is confirmed, treat and then investigate the underlying epilepsy etiology, since new-onset NCSE in an older adult often reflects a structural or metabolic cause requiring ongoing management.