Do you agree with inpatient workup for this patient whose mental status has now returned to baseline? If so, what workup would you pursue next?
►Dr. Fehnel. This patient requires inpatient admission to further evaluate the underlying etiology for his acute change in mental status. The improvement of his presenting deficit and largely normal neurovascular imaging make a neurovascular etiology less likely, but a careful risk factor evaluation for CVA/TIA should be performed, including continuous cardiac telemetry to detect atrial fibrillation. Magnetic resonance imaging (MRI) of the brain should be performed to rule out occult stroke and evaluate for a structural etiology given the more likely diagnosis of complex partial seizure. An electroencephalogram (EEG), preferably 24-hour continuous recording, should be performed. Without a clear toxic or metabolic etiology thus far to explain his acute global waxing-waning alteration in mental status and likely new-onset complex partial seizures, I would also pursue lumbar puncture for cerebrospinal fluid examination.
►Dr. Li. The hospital course was notable for episodes of acute combativeness and confusion. An MRI of the brain was deferred due to reports from the patient’s family of retained shrapnel in the lumbar spine. Routine EEG showed no seizure activity. This was followed by continuous video EEG monitoring, which showed subclinical seizure activity with a right temporal focus. He was started on valproic acid with improvement in his agitation, though confusion continued. He was discharged to an inpatient geriatric psychiatry nursing home with diagnosis of seizures and acute delirium.
Dr. Fehnel, seizures are often part of the workup for unexplained encephalopathy. In this case, the routine EEG was unrevealing, while the continuous video EEG proved valuable. In what situations would you pursue a continuous video EEG in addition to a routine EEG?
►Dr. Fehnel. EEG monitoring is only as good as the window of time during which the study is performed. If the suspicious clinical event is captured during a routine recording or an area of focal slowing is detected, a shorter study may be entirely sufficient. However, in cases where there is no clear alternative explanation, a patient’s mental status does not return to normal, or in the setting of mental status fluctuations without explanation, continuous video-EEG monitoring for at least 24 hours is indicated. While the prolonged study raises sensitivity, the exact duration of EEG recording required outside of the intensive care unit setting remains debated.2
►Dr. Li. If his encephalopathy were due to seizures alone, I would expect improvement in his mental status during interictal periods, which does not appear to be the case here. Do you feel the seizures alone can explain his encephalopathy?
►Dr. Fehnel. Complex partial seizures and the medications used to treat them can confound the examination of patients during the interictal period. We commonly debate postictal encephalopathy vs residual effect of benzodiazepines and rapid dose escalation of antiepileptic drugs as culprit in a patient’s prolonged alteration in mental status. Serial clinical examinations, continuous EEG monitoring to rule out ongoing subclinical seizures when appropriate, and judicious use of potentially sedating medications is the most helpful approach. The key issue here is the bimodal distribution of new-onset seizures. Among children there is a higher incidence of genetically related seizure disorders; whereas among adults, “acquired” and structural etiologies are more common. For this case, a more careful evaluation of acquired/structural etiologies for new-onset seizures is indicated.
►Dr. Li. At the geriatric psychiatry nursing home, the patient continued to be combative and refused medications. He was readmitted to the VABHS with encephalopathy of unclear etiology. An expanded encephalopathy workup was unrevealing (Table 2).
