AWAKE EVOKED ELECTROMYOGRAPHY RECORDING FROM THE CHRONICALLY IMPLANTED RAT

Investigation of the effects of various factors on nerve regeneration has been compromised by the lack of an accurate and objective techniqu e which can monitor dynamic changes in the status of nerve-muscle inne rvation over the entire course of regeneration. The approach of evoked electromyography (EEMG) was adopted to obtain temporal and quantitati ve data during nerve regeneration. Initially, transcutaneous nerve sti mulation and percutaneous muscle recording was performed, but the appr oach was abandoned because of the high intertest variability (20% aver age deviation) and requirement for anesthesia during testing. A new ap proach using chronically implanted stimulation and recording electrode s was adopted in an attempt to circumvent these problems. Initial acut e studies performed in the hindlimb of the anesthetized rat identified stable EEMG recording sites with sciatic nerve stimulation. In a seco nd study conducted in chronically implanted unanesthetized unrestraine d animals, EEMG recording from these sites demonstrated remarkable sta bility with an average intertest variability of only 5%. Preliminary r esults have been obtained with this technique in monitoring the progre ssion of hindlimb reinnervation following crush and transection nerve injuries.