Adult-Onset Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-Like Episodes (MELAS) in a Patient Without Significant Family History.

This case reports a 53-year-old Caucasian female previously diagnosed with viral encephalitis and Fahr's Syndrome who presented with altered mental status. Shortly after arrival, she displayed severe lactic acidosis and was transferred to the intensive care unit (ICU), where she had a brief seizure. Neurological workup was performed including carotid ultrasound, magnetic resonance angiography (MRA) brain, and computed tomography (CT) angiogram of the neck, all of which were unremarkable. Initial magnetic resonance imaging (MRI) performed showed small, acute ischemic foci in the bilateral occipital lobes and medial left thalamus. Subsequent diffusion-weighted imaging (DWI) MRI of the bilateral occipital lobes showed vasogenic edema, a common finding in Mitochondrial Encephalopathy, Lactic Acid, and Stroke-like episodes (MELAS). The patient was given Levetiracetam and managed supportively. She was progressively extubated and her seizure symptoms and lactic acidosis resolved. Our case represents a unique case in which a patient with non-contributory family history is first diagnosed with MELAS after age 40 after her symptoms were initially attributed to other pathologies.