원위부 근이양증

Abstract

Although muscle disease classically presents with proximal extremity weakness, some myopathic disorders, including several types of muscular dystrophy, result in predominantly, or exclusively, distal muscle involvement. Accurate diagnosis of these relatively uncommon conditions can be challenging for the clinician, because of unusual phenotype and significant overlap in the clinical features of theses entities. The clinical characteristics of this patient were slowly progressive symmetrical muscle weakness and wasting of all 4 extremities in distal part. Serum muscle enzymes were slightly increased. The prominent EMG findings were myopathic changes, but reduced recruitment was occasionally found in some distal muscles. The muscle biopsy finding of right gastrocnemius showed the non-specific finding of myopathy. Among various perviously described distal myopathies, several diseases have been established as clinically and genetically distinct entities. The most representative diseases are dominantly inherited Welander distal myopathy and tibial muscular dystrophy, and the recessively inherited distal myopathy with rimmed vacuoles (Nonaka myopathy) and distal muscular dystrophy (Miyoshi myopathy). In this case clinical characteristic was compatible with Welander distal myopathy, but genetically not consistent with autosomal dominant inherited disease. Because this case showed overlap in the clinical feature of these disease entity we concluded this case was nontypical early adult onset distal myopathy.