Chronic progressive external ophthalmoplegia. I. A quantitative histochemical study of skeletal muscles

This study quantitates the major morphological and cytochemical changes in limb muscle biopsies from 37 patients with the syndrome of chronic progressive external ophthalmoplegia (CPEO). The aim was to assess the value of limb muscle biopsy in the diagnosis of this syndrome; to define the myopathological changes and to determine whether there were any specific clinico-pathological correlations. Patients were divided into three clinical groups--11 patients with CPEO with facial and/or limb muscle weakness; 10 with CPEO with facial and/or limb muscle weakness and a positive family history; 16 with CPEO with one or more of the following: pigmentary retinopathy, cerebellar ataxia, pyramidal signs and peripheral neuropathy. The following parameters were measured: the proportions of histochemical fibre types, the muscle fibre areas and the percentage of muscle fibres showing increased oxidative enzyme activity. Pooled results for each of the clinical categories were compared. Statistical analysis of fibre areas and the percentage of fibres with increased oxidative enzyme activity, showed that group 2 differed from the others (p less than 0.05). Patients in group 2 showed the highest incidence of type 1 fibre hypertrophy, type 2A atrophy and the lowest incidence of fibres with increased oxidative activity. Fibre type disproportions occurred in all three groups but the differences were not significant.