[Adult polysaccharide storage myopathy].

A first Japanese case of an adult polysaccharide storage myopathy (APSM) was reported. A 30-year-old Japanese male was admitted because of weakness of the lower limbs. The onset of the symptoms was at the age of 23. Neurologically he had moderate weakness of proximal limb muscles involving the lower limbs more than the upper and slightly decreased vibratory sense in the feet. His gait was waddling. The following laboratory values were obtained; SGOT 45 I.U., SGPT 83 I.U., CPK 218 I.U., UA 8.3 mg/dl. Ischemic exercise test of the forearm showed a normal rise of venous lactate. EMG revealed a mixture of myopathic and mild neurogenic patterns characterized by motor units of short duration and low amplitude with intermittent high amplitude potentials, fibrillation and fasciculation. There were also prominent myotonic discharges without clinical myotonia. MCV was normal, however sural nerve SCV was slightly slow (lt. 36/m, rt. 38 m/s). Muscle biopsy revealed vacuolar myopathy. Most vacuoles contained basophilic, PAS-positive, diastase-resistant and Lugol's iodine-negative material. With ATPase staining there was type 1 fiber predominance (84%), but the vacuoles were predominantly seen in type 2A fiber. In ultrastructural study, the storage material was located under the sarcolemma and in the areas of the intermyofibrillar network. No delimiting membranes were seen. At higher magnification, these masses were consisted of filaments. Therefore the storage material was considered to be unusual polysaccharide. Glycogen storage disease was suspected, however, biochemical study of the muscle specimen disclosed no enzymatic defect including branching enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)