Non familial juvenile distal spinal muscular atrophy of upper extremity.

An uncommon variety of non familial, juvenile onset, spinal muscular atrophy with asymmetric distal upper extremity affection is described. One hundred and two patients with a one to 14 year follow up are analysed. Spinal muscular atrophies with a distal distribution are rare. However, in the past three decades, previously unrecognised varieties of neurogenic muscular atrophy have been described in Asia (Japan, India, Sri Lanka and Singapore) under a variety of names. These provide interesting data for discussion of Asian neurogenic muscular atrophies with distal affection, in the context of diseases of the motor neuron.