Implications of longitudinal muscle fibre splitting in neurogenic and myopathic disorders.

Histological and electromyographic studies indicate that longitudinal muscle fibre splitting is a common finding in neuromuscular disorders. Separated fragments derived by splitting may undergo degeneration or enlarge to become separate, innervated fibres, thus leading to an increased number of fibres within motor units. Splitting may, therefore, lead to the formation of clusters of fibres of uniform histochemical type, but of variable diameter and length, both in neurogenic and in myopathic disorders. Fibre splitting is thus a factor leading to functional compensation in these disorders.