2714 Case report: a first presentation of mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) mimicking acute encephalitis

CaseA 51-year-old woman presented with focal motor seizures and confusion. Relevant history included diabetes mellitus and sensorineural hearing loss. She was given intravenous levetiracetam, and acyclovir for suspected encephalitis. She required admission to ICU for agitation. Serum lactate was 7.2 mmol/L, attributed to seizures. Lumbar puncture was acellular with raised protein (0.64 g/L) and glucose (6.3 mmol/L). Gram stain and culture showed no organisms, whilst multiplex PCR and limbic encephalitis/antineuronal antibodies were negative. EEG showed right lateralised periodic discharges. MRI brain showed FLAIR hyperintensity in the right temporal lobe.A maternal family history of dementia, diabetes, and hearing loss was elicited. On serial CSF, lactate was raised at 5.1 mmol/L. Mild proximal weakness was detected, with normal creatinine kinase. MR spectroscopy showed a parietal lobe lactate peak. Serum biomarkers of mitochondrial disease showed elevated GDF15 (3180 ng/L; normalG variant found in ~1 in 400 people.1 It can present later in life, including mimicking acute encephalitis. A personal or family history of diabetes, hearing loss, or myopathy should alert clinicians to the possibility of MELAS, especially when other encephalitides are excluded.ReferenceManwaring N, Jones MM, Wang JJ, Rochtchina E, Howard C, Mitchell P, Sue CM. Population prevalence of the MELAS A3243G mutation. Mitochondrion 2007;7:230–233. doi:10.1016/j.mito.2006.12.004