Abstract
BACKGROUND: Brief electrical stimulation (ES) of injured peripheral nerves for 1 hour has been shown to accelerate nerve regeneration with proximal action potential conduction to the neuron cell body, a requirement to elicit therapeutic benefit. Local anesthetic is often used to manage pain in patients. However, using lidocaine after ES therapy has been controversial. We assessed the effects of extraneural usage of lidocaine after ES therapy on nerve regeneration in a rodent nerve injury model. METHODS: Lewis rats underwent tibial nerve transection and immediate repair and randomized to 4 groups: control (REP), extraneural lidocaine alone (REP + LIDO), 60-minute ES (60 ES), and 60-minute ES with extraneural lidocaine (60 ES + LIDO). The tibial nerve was retrograde labeled distally from the neurorrhaphy 28 days post repair. Spinal cords and dorsal root ganglia were harvested to assess motor and sensory neuron counts. Data were analyzed using 1-way analysis of variance (ANOVA) with a post-hoc Tukey correction. RESULTS: Using lidocaine after nerve repair did not affect nerve regeneration in the control group (REP vs REP + LIDO) or ES group (60 ES vs 60 ES + LIDO), with motor and sensory neuron counts not statistically different between groups. Electrical stimulation therapy showed at least a 60% increase in motor and sensory neuron counts than controls, a statistically significant effect (P < .001). CONCLUSIONS: Extraneural usage of lidocaine after ES does not abolish the improved effect of ES on nerve regeneration. Future clinical studies should evaluate the usage of subcutaneous injection of lidocaine post ES for analgesia control.