Acute encephalopathy of the temporal lobes leading to m.3243A>G. When MELAS is not always MELAS.

MELAS syndrome (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) is a rare genetic condition whose differential diagnosis is often posed with juvenile stroke, but more rarely even with inflammatory/infectious encephalitis, causing diagnostic challenges. Here we report the case of a young man harbouring the m.3243A>G MELAS mutation presenting an acute onset mimicking the clinical and neuroimaging features of infective encephalitis.