The effects of autologous nerve transplants on motor and sudomotor reinnervation by regenerative axons

The functional reinnervation rate of sweat glands (SGs) and muscle in the mouse paw were compared following resection of a 4 mm segment of sciatic nerve. Repair was by graft of the same segment with epineural sutures or by suturing the proximal and distal stumps to a teflon tube that contained saline alone or saline plus the unattached nerve segment. Pilocarpine activated SGs first reappeared at 23 days postoperation in mice with a direct graft, at 29 days in mice with a nerve transplant in the tube, and at 32 days in mice with an empty tube. The number of reinnervated SGs increased progressively in number to a maximum of about 65% of the control counts by 60, 60 and 67 days, respectively. Compound muscle action potentials evoked by sciatic nerve stimulation were first recorded from the interossei muscles at 24, 27 and 31 days postoperation in the same groups of mice. The action potential amplitude increased to average values of about 2 mV by 58, 62 and 69 days. These results indicate that a direct nerve graft allows faster and higher functional recovery than tubulation repair, and that a nerve transplant slightly accelerates the reinnervation rate, probably due to the presence of nerve trophic products inside the tube. Unmyelinated and myelinated axons regenerated at equal rates.