Suspected Post-ictal Psychosis in Temporal Lobe Epilepsy Secondary to Human Herpesvirus 6 Encephalitis

Human herpesvirus 6 (HHV-6) may lead to temporal lobe epilepsy (TLE). Psychotic syndrome frequency in the setting of TLE is 7% to 11%. We report a case of post-ictal psychosis (PIP) secondary to TLE in the setting of HHV-6 encephalitis. A 58-year-old male presented with a two-day history of severe confusion, personality changes, and new-onset psychosis. Lumbar puncture was positive for HHV-6. Electroencephalogram (EEG) revealed left temporal sharp waves during drowsiness and sleep, suggestive of focal epileptiform discharges without clinical seizures. Valproate and olanzapine were employed for epilepsy and agitation. Psychosis and confusion resolved with subsequent discharge. Out of the other diagnoses, PIP in the setting of TLE secondary to HHV-6 given the clinical response to acyclovir. While HHV-6 encephalitis may cause TLE, this patient did not have a history of seizures and EEG did not capture active seizures. It is unclear if the sharp waves were incidental or indicative of TLE. Additionally, PIP is seen more commonly with left-sided EEG changes. Low-dose olanzapine was efficacious in resolving symptoms, which is typical in PIP. Both HHV-6 encephalitis and TLE have the potential to cause memory impairments and personality changes, which were seen in this patient. Patients with both TLE and PIP are less likely to exhibit focal ictal discharges than those with only TLE, which may explain the absence of active seizure activity on EEG.