Congenital mitochondrial cytopathy and chronic progressive external ophthalmoplegia.

BACKGROUND

Chronic Progressive External Ophthalmoplegia (CPEO) encompasses different conditions having in common a slowly progressive external and general ophthalmoplegia. The discovery of CPEO is suggestive of mitochondrial cytopathy, but this is not necessarily so.

CASE REPORT: We report here a case, presenting at age 9 months, characterized by bilateral blepharoptosis and partial third nerve oculomotor deficiency, with no nystagmus. Mitochondrial cytopathy was suspected on cranial MRI and confirmed by muscle biopsy. Enzyme studies revealed a defect on the complex I respiratory chain. This case is unique in that the symptoms completely resolved under a Ketogen diet.