Noninvasive electrodiagnostic and motor function assessment of the common fibular nerve regeneration in the rabbit hindlimb.

BACKGROUND: Although widely used, the rat model remains poorly transferable to humans for peripheral nerve regeneration studies. The rabbit is a much better choice from an anatomical perspective. However, it remains little used due to the lack of available literature. The aim of this article is to demonstrate the feasibility and effectiveness of an electrophysiological protocol combined with a motor function assessment to analyze nerve repair. METHODS: Ten white New Zealand rabbits underwent a 4 cm transection of the fibular nerve. Autograft regeneration over 36 weeks was compared to non-repaired controls. The compound muscle action potential (CMAP) was recorded in the tibialis anterior and the extensor digitorum brevis. An electromyogram (EMG) was obtained after needle insertion and resting muscle activity recording. The electrophysiological results were compared to the toe spread index (TSI), which assesses the motor functional recovery promoted by fibular nerve regeneration. RESULTS: The autograft group regeneration starts between weeks 18 and 21 and normal EMG was observed around the 30th week. These electrophysiological results were compared to the well-defined toe spread reflex. This motor test showed a significant functional return of 59% at 36 weeks (p < 0.05). Rabbits regain nearly 80% of their muscle mass. CONCLUSION: Nerve conduction allows detection of nerve regeneration of the muscle while electromyography indicates when muscle activity returns to normal. These studies are reliable and non-invasive techniques to evaluate fibular nerve regeneration in the rabbit's hindlimb. Nonetheless, it is necessary to have qualified personnel, since inter-manipulator variations have been observed.