[Distal spinal muscular atrophy]

Chronic spinal muscular atrophy usually presents in childhood or adolescence, generally as predominant proximal muscle weakness. Other less common forms involving distal muscles can be either partial or generalized and their prognosis is relatively good. At least three well-defined types can be identified: a) a form located in the upper extremities that typically affects young men, is not familial and is highly prevalent in Asia; b) a more generalized form that can be either familial or isolated and that resembles Charcot-Marie-Tooth disease in the distribution of muscle weakness and prognosis, and c) another generalized form that starts in and mainly involves the upper extremities, is inherited in an autosomal dominant manner and is accompanied by laryngeal involvement. We review the literature and describe 27 patients with distal spinal muscular atrophy resembling Charcot-Marie-Tooth disease.