MYOPATHIES WITH ABNORMAL MITOCHONDRIA

Abstract

Among 135 consecutive patients with myopathy, 17 showed abnormalities in the mitochondria of muscle. In 8 of these patients the abnormalities were demonstrated by EM. In all patients Gomori trichrome stain showed red masses at the sites of the mitochondria and diformazan deposits when stained for mitochondrial enzymes. The patients were divided into 3 groups. Group 1 had 9 patients with weakness of the extra-ocular muscles, either alone or associated with weakness of skeletal muscles and non-muscular signs. One patient with the oculo-cranio-somatic syndrome had 2 affected sibs. Group 2 had 4 patients with a facioscapulohumeral distribution of weakness. Three (2 sisters and 1 maternal aunt) were in the same family, and the 4th patient had an affected sister. Group 3 had 4 patients who were clinically heterogeneous. When mitochondrial alterations were the only pathological change in many fibers in a muscle, they were most often associated with an ocular or oculo-cranio-somatic syndrome. Electromyography [EMG] showed changes indicating or suggestive of myopathy in all but 1 patient. There was a discrepancy between severe changes in the EMG and nearly normal fibers by hematoxylin and eosin and van Gieson stains. Serum creatine kinase was increased in 10 of 17 patients, in most 2-4 times the upper limit of normal.