[Adult-onset nemaline myopathy with distal muscle atrophy--case report]

We report the case of a 35-year-old male who started gradually developing gait difficulty and atrophy in the distal extremities at the age of 20. In addition to the motor symptoms, skeletal abnormalities such as high-arched palate and pes cavus were also noted. Muscle biopsy revealed numerous nemaline rods and type I atrophy--the pathologic hallmarks of congenital forms of adult nemaline myopathy (ANM). To elucidate the distribution of affected muscles in ANM, we reviewed 61 case reports of ANM and classified these cases into the 3 subcategories proposed by Suzuki et al., as follous: (1) congenital adult-aggravation form, (2) congenital adult-onset form, and (3) non-congenital adult-onset form. Our review suggested that the proximal muscles were predominantly affected both in patients with the congenital adult-onset form and in those with the non-congenital adult-onset form, whereas the distal muscles were affected in approximately half of the patients with the congenital adult-aggravation form. Therefore, on the basis of the characteristic muscle pathology and skeletal deformities observed, we concluded that this patient corresponded to the congenital form of ANM with skeletal abnormalities. A unique feature of this case was the relatively late onset. Therefore, we propose that ANM should be considered as a possible diagnosis for patients with adult-onset distal myopathy, particularly for those with skeletal abnormalities.