Benign focal amyotrophy: a longitudinal study (13-15 years) in 3 cases.

We report three young patients, two male and one female, with B.F.A., followed up clinically and neurophysiologically (two after a muscle biopsy) for 13-15 years. We confirm also in Italy the existence of this monomelic type of muscle atrophy (Hirayama type), already described in other countries, which shows a mild progression of the amyotrophy during the first two years and thereafter remains stationary. In our opinion the disorder represents a segmental transitional form of A.L.S. in which some "delaying" factor, unfortunately not yet demonstrated, is operating. In fact the neurophysiological studies, apart from its attribute of remaining segmentary, do not show differences between B.F.A. and the other forms of motoneuron disease.