Scapuloperoneal myopathy is a form of myopathy so named because of the involvement of the muscles in the shoulder girdle. Scapuloperoneal myopathy usually presents in young adulthood but may present in early adolescence. Muscle weakness is due to atrophy of the affected musculature. The atrophy raises the question of whether this is truly a myopathy or whether it is actually one of the spinal muscular atrophies. Muscle biopsy reveals dead tissue as well as generating fibers and increased connective tissue; atrophy tends to be focal rather than diffuse.