[A case of adult-onset nemaline myopathy (adult-onset rod disease) with distal muscular hypertrophy].

We reported a 40-year-old male with adult-onset nemaline myopathy (adult-onset rod disease) showing muscular hypertrophy of distal limbs. At the age of 25, he noticed thinness of his thighs. Difficulty in climbing stairs slowly progressed from the age of 35. On admission neurological examination revealed muscular weakness and atrophy of proximal limbs and hypertrophy of distal flexors. Normal laboratory tests included serum creatine kinase, myoglobin, aldolase and pyruvate. Electromyography revealed severe neurogenic changes in the right biceps brachial muscle and the right quadriceps muscle, and moderate changes in the right gastrocnemius. Biopsy specimen of the deltoid muscle demonstrated type 1 fiber predominance and type 1 fiber atrophy, and there was small group atrophy and type grouping. Abundant nemaline rods were found mainly in type 1 fibers (81.5%). In order to evaluate hypertrophy of calf muscles, T1-weighted MRI of lower extremity was performed. While transaxial images through mid thigh showed moderate fatty replacement, increased volume and little fatty replacement were found in the mid calf. Therefore, hypertrophy of the calf muscle seemed to be compensative hypertrophy. But in this case neurogenic factors were indicated electromyographically and histologically. These findings may advocate the notion that neurogenic factors involved not only congenital but adult-onset rod disease.