A case of progressive external ophthalmoplegia (Kiloh-Nevin type) with abnormal mitochondria. Clinical, histochemical and ultrastructural findings.

A case of progressive external ophthalmoplegia is described, in which the onset of the illness was at 28--30 years, with fatigability and muscular pains in the lower limbs as presenting symptoms. At 36--37 years weakness of the mimic muscles also appeared and fatigability and muscular pains spread to the upper limbs: EMG examination showed signs of light myopathic involvement of the shoulder-girdle muscles, so that a muscular biopsy was performed (right deltoid). Histoenzymologic studies showed the presence of generally atrophic dark fibres, which can be brought about to red-ragged fibres. Ultrastructural study showed bizarrely shaped mitochondria, with dense matrix and circular and confluent cristae, which were found in fibres with plenty of indifferent sarcoplasm and with anomalies in myofibrils. No mitochondrial inclusions were seen.