[Bioelectric characteristics of spinal muscular atrophy].

On the basis of the clinical material of the Department of Neurology, Medical Academy in Warsaw the author discusses the bioelectric characteristics of infantile and juvenile spinal muscular atrophy. Attention is called to the specific character of resting firing units in infantile type. On the background of a neurogenic damage pattern the so called "spinal" features of the electromyogram are much more pronounced in the juvenile form of the disease. Motor fibre velocity in small children in the so called group I achieves normal values for a given age later than in healthy children, in long-standing cases of the juvenile form the minimal velocity may be decreased or the conduction velocity may be uniform at the level of the normal maximal velocity. The value of electromyography in the separation of Werdnig-Hoffmann disease from the group of the so called floppy children, and in the differential diagnosis between juvenile spinal muscular atrophy (mainly Kugelberg-Welander disease) and muscular dystrophy is emphasized.