[A case of senile onset rimmed vacuole myopathy with proximally dominant involvement]

A 73-year-old woman with progressive proximal-dominant muscular atrophy and weakness was described. She had been well until 70-year-old, when she found difficulty in standing up from sitting position. At age 72 years, she could not raise her arms. Neurological examination showed muscular wasting and weakness in the proximal parts of extremities, shoulder and pelvic girdle. In the thigh, the flexors and adductors were severely affected. Muscular weakness was also observed in m. tibialis anterior. Serum CK and aldolase were normal. Electromyography showed low voltage short duration motor unit potentials with positive sharp waves and fibrillations. Rimmed vacuoles were observed in 4.8% of muscle fibers in biopsy sample obtained from right m. quadriceps femoris. No inflammatory cells, PAS-positive materials and inclusion bodies were observed in the sample. This case differs from distal myopathy with rimmed vacuoles, because the onset was very late and her muscular weakness and atrophy was proximal dominant. This case also differs from inclusion body myositis, because muscle biopsy revealed no inflammatory cells or inclusion body.