• mitochondrial cytopathy
• respiratory failure
• optic atrophy

Leber's hereditary optic neuropathy (LHON) is a maternally inherited disease of mitochondrial DNA. Several mutation sites have been described. All have been associated with visual loss, but mutations at nucleotide position 11778, 3460, and recently 14484, have also been associated with a multiple sclerosis (MS)-like disease.^1–3

We report a woman with undiagnosed LHON who presented with life threatening ventilatory failure.

A 39 year old woman who had had bilateral synchronous severe visual loss to perception of light some two years earlier (see below), was admitted after a two week illness with a purulent cough. She was confined to bed and had received oral antibiotics from her general practitioner. She had a history of chronic headaches but reported no change in their frequency before presentation. On admission she was obtunded with a Glasgow Coma Scale (GCS) score of 3/15. She was hypoventilating, with a severe respiratory acidosis. Arterial blood gas (ABG) showed pH 7.04, Po₂ 40.9 kPa, Pco₂ 16.2 kPa, and bicarbonate 22 mmol/l. She was admitted to an intensive care unit and ventilated with later tracheostomy. She was weaned from the ventilator after 31 days and transferred to a ward. Five days later she had a second respiratory arrest …