A Case of HSV Encephalitis Misdiagnosed as Worsening Psychiatric Condition: A Case Report

Herpes simplex virus (HSV) encephalitis is uncommon but serious condition that can lead to significant morbidity and mortality if not promptly diagnosed and treated. Atypical presentations are becoming more common with improved diagnostic methods, but they remain underexplored. We present the case of a 29-year-old known patient with schizophrenia for the past four years on olanzapine 5 mg PO BID who initially presented to psychiatry emergency with difficulty in proper communication, auditory hallucination, blurring of the eyes, and depressive symptoms for which olanzapine was discontinued, trifluoperazine 5 mg PO daily was initiated, and lorazepam 1 mg p. o. nocturnal was added after the diagnosis of schizophrenia relapse. Despite the above management, the patient presented with abnormal body movements characterized by up-rolling of the eyes, drooling of saliva, jaw jerking followed by repetitive flexion and extension of the upper and lower extremities, and postictal loss of consciousness. He also had low-grade fever and headache for 5 days. The patient was started on phenobarbitone 100 mg PO nocturnal and escalated. However, the frequency of seizures increased. Clinical evaluation, MRI, and EEG eventually confirmed HSV encephalitis. The patient was administered acyclovir 500 mg intravenously every 8 hours for 21 days. After antiviral therapy, the patient was discharged with antiepileptic and antipsychotic medications 18 days after the seizure-free period with significant improvement. Here, we illustrate that HSV encephalitis can present in unfamiliar manner and reinforce the need for a low index of suspicion and early empirical use of acyclovir until definitive laboratory test results are available.