Nerve regeneration and reinnervation after limb amputation and replantation: clinical and physiological findings.

A 22-year-old male was studied 3 1/2-4 1/2 years after a traumatic section-avulsion amputation of the left upper extremity at the level of the distal humerus. The arm was reattached after a cold ischemia time of 4-5 hours and good vascularization was obtained. The ulnar nerve was repaired early with an end-to-end juncture while the median and radial nerves were repaired after seven months delay using a combination of vascularized radial nerve and nonvascularized sural nerve grafts. Some intrinsic hand muscle function had recovered. Pin-prick and touch sensation was present in all digits, although localization of touch stimulation was poor. Evoked motor responses had recovered by 25-50% of control amplitude in ulnar-innervated and by 10-25% in median-innervated muscles. Amplitudes of sensory responses from digit V had recovered by 25% and from digits I and III by 1-5%. Fast-adapting touch receptors had become reinnervated. There was electrophysiological evidence of aberrant sensory regeneration and of abnormal connections between sensory and motor fibers. Digital blood flow measurements suggested the presence of vascular obstruction in vessels of the replanted upper extremity. However, the digital vasoconstriction during cold exposure indicated regeneration of sympathetic nerve fibers.