Recurrent Stroke Events Secondary to a Late Presentation of Mitochondrial Encephalomyopathy With Lactic Acidosis and Stroke-Like Symptoms (MELAS) Syndrome.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like symptoms (MELAS) is a rare mitochondrial disorder that typically presents before the age of 40 with most patients diagnosed before the age of 20. Symptoms and signs typically include mitochondrial myopathy, encephalopathy with stroke-like episodes, seizures and/or dementia, and lactic acidosis. We present a case of a 56-year-old lady presenting with recurrent ischaemic strokes and seizures associated with non-territorial low attenuation areas on brain imaging. Together with a raised serum lactate and background history of Syndrome of Inappropriate secretion of Anti-Diuretic Hormone (SIADH), genetic analysis was carried out that confirmed the presence of the most common mutation associated with MELAS syndrome which is m.3243A>G mutation. This case raises the importance of considering a diagnosis of inherited mitochondrial disorder when faced with recurrent atypical stroke-like episodes, when neuro-imaging is inconsistent with ischemic infarction, even in adults or elderly individuals. It also highlights the importance of background history and associated conditions that should be put into consideration when thinking about differential diagnosis.