Fatal cerebellar oedema in adult Leigh syndrome

A 19-year-old female university student presented with a 5-week history of generalised weakness, unsteady gait and breathlessness. There were no symptoms of recent infection. Her only medical history was long-standing symmetrical 40 dB sensorineural hearing loss. On neurological examination, she had hyperpnoea, mild non-fatigable global weakness, bilateral ptosis, soft speech and absent lower limb reflexes. The MR scan of brain showed symmetric T2-hyperintensities surrounding the third ventricle, hypothalamus and brainstem on fluid-attenuated inversion recovery sequences, suggestive of Leigh syndrome (figure 1). Lumbar puncture showed an opening pressure of 8 cm water. Cerebrospinal fluid (CSF) was acellular, protein 0.38 g/L (normal