The morphological sequences in man of de- and reinnervation in free muscle transfer with microneurovascular anastomoses.

Muscle biopsies from two patients treated by free gracilis muscle transfer and micro-neurovascular anastomoses for long standing facial palsy due to previous damage to the facial nerve during removal of tumours were examined by histochemistry and electron microscopy. Sequential muscle biopsies of one case taken at various intervals after transferring the muscle permitted the study of events of de- and reinnervation of human skeletal muscle. The changes in the early stages of denervation included atrophy of type 2B fibres. This was followed by progressive atrophy of all fibre types, distortion of the internal structure of the muscle fibres with the incidence of various cytoplasmic inclusions. Massive necrosis of the muscle did not occur. A prominent increase in satellite cells and their maturation to myotubes and new muscle fibres were evident. Reinnervation occurred with the formation of neuromuscular junctions some of them being at preformed sole plates. Fibre type grouping was apparent in addition to other changes such as the occurrence of targetoid hypertrophied muscle fibres. These changes are similar to those described previously during de- and reinnervation studies in experimental animals.