Cross-neurotization of the caudal brachial plexus with the contralateral C-8 ventral nerve branch in the cat. Potential surgical applications, effects of graft collection on the healthy donor limb and results

Abstract

Contralateral transfer of the right, eighth ventral nerve branch (C8) (C8 cross-transfer - C8CT) was performed in 6 adult cats, in which the caudal part of the left brachial plexus (C8 and T1) had been severed, in order to mimic nerve root avulsion. Clinical and electrophysiological parameters, muscle contraction force measurements and histology were used to evaluate the effects of the surgery in a 14- to 36-month follow-up. The right forelimb (donor side) was clinically normal (no lameness) in all the cats at the end of the study. Electromyography performed 14 days after surgery revealed denervation fibrillation potentials in both forelimbs. Fibrillation potentials disappeared in all the cats at the end of the study. Direct stimulation of the right C8 ventral branch induced motor and sensory evoked potentials in the left limb muscles in all the cats. The left to right contraction ratio of the extensor carpi radialis muscle was approximately 1. This experimental study demonstrates that C8CT enables re-innervation of the contralateral brachial plexus and allows the establishment of new functional neuromuscular units. This can in turn enable the restoration of function, and could potentially lead to partial recovery after caudal brachial plexus avulsion in the cat.