[MRI findings in studies of distal myopathy with rimmed vacuoles]

A case of distal myopathy with rimmed vacuoles was studied with MRI, which showed a characteristic distribution of the affected muscles. A 41-year-old man who presented a slowly progressive weakness in his lower legs starting 11 years previously was admitted to our hospital of further investigation. Neurological examinations showed muscular wasting and weakness in the neck flexors, the flexors of the forearm, the flexors and adductors of the thigh and the extensors of the lower legs. Needle electromyography showed a myopathic pattern. Muscle biopsy revealed a variation in fiber size, an increase in internal nuclei, fatty infiltration and scattered rimmed vacuoles in a histochemical study. Electron microscopy revealed that rimmed vacuoles contained numerous lamellar bodies and glycogen particles. T1 and T2 weighted MRI showed high signals in the m. adductor of thigh m. biceps femoris, m. semimembranosus, m. semitendinosus, m. tibialis anterior, m. tibialis posterior, m. extensor digitorum longus, m. extensor digitorum brevis, m. peroneus, and m. gastrocnemius. There were three merits for the application of MRI to distal myopathy, (1) easy detection of the affected muscles as fatty change is expressed with a high signal intensity by MRI, (2) no affection by the presence of bones in MRI, and (3) the possibility to have a transverse section and a sagittal and coronal section in MRI. In this case MRI was very useful to detect the affected muscles and to observe the progress.