Nerve Action Potential Recording Method and Equipment

OBJECTIVE: Nerve action potential (NAP) recording is a proven and useful tool in the surgical management of nerve injury. Understanding its materials and methods as well as its pitfalls and limitations is necessary for successful and routine use of this tool. METHODS: The basic electrophysiology of nerve and its implications in the setting of nerve trauma and regeneration are reviewed. Electrode design and electrode placement are discussed. The use of simple electromyographic/nerve conduction machines for intraoperative recording of NAPs is developed, along with some of the technical problems that result from electrophysiological recording in an electrically hostile environment. RESULTS: NAP recording is a good indicator of useful recovery in nerve trauma. The presence and demonstration of an NAP is associated with a 90% chance of recovery to a useful motor state. CONCLUSION: NAP recording provides useful information regarding the regenerative potential of a damaged nerve long before that potential is clinically evident. This information is critical in the optimal management of nerve injuries. The techniques of NAP recording are straightforward, but attention to detail is important, and full understanding of the method is required.