Herpes Simplex Virus Encephalitis: Atypical Presentation as a Right Middle Cerebral Artery Stroke.

Herpes simplex virus encephalitis (HSVE) is a medical emergency associated with high mortality and morbidity. Definitive diagnosis is established by history, clinical examination, neuroimaging studies, supportive electroencephalogram (EEG) findings, and cerebrospinal fluid (CSF) analysis. We report a case of HSVE presenting as a stroke mimic in a 76-year-old female with a history of atrial fibrillation on warfarin. She was admitted to our medical intensive care unit with intermittent fever, lethargy, and new onset left-sided hemiparesis. A computed tomography (CT) of the head showed a right middle cerebral artery (MCA) acute ischemic stroke with midline shift and a dense right MCA sign. Brain magnetic resonance imaging (MRI) showed evidence of acute stroke with consideration of herpes encephalitis. CSF analysis was positive for herpes simplex virus (HSV) type one. She recovered with high-dose intravenous acyclovir therapy. Our patient was a diagnostic dilemma, initially being diagnosed with an acute ischemic stroke and yet found to have HSVE, which mimicked an acute ischemic stroke. Delay in treatment may result in devastating clinical outcomes that may include severe cognitive, focal neurological deficits, persistent seizures, and even death. This case highlights the importance of a multidisciplinary approach and the need for increased awareness of an atypical presentation of HSVE among emergency physicians, neurologist, intensivists, and radiologists.