Semi-quantitative electromyography as a predictor of nerve transfer outcome.

OBJECTIVES: Evaluate correlation between donor nerve semi-quantitative electromyography (sqEMG) and strength outcome in nerve transfer surgery. METHODS: Retrospective review of pre-operative donor nerve semi-quantitative neurophysiology and post-operative recipient muscle force after at least one-year follow-up. The semi-quantitative technique is the average motor unit number estimate associated with needle recorded interference patterns in the donor muscle (IP-AMUNE), which was correlated with hand-held manometry, standardized as a percent of the contralateral arm, using multivariable linear regression with backward selection. RESULTS: Twenty-eight nerve transfer cases were included. The correlation between the donor nerve IP-AMUNE and the recipient muscle strength was moderate to strong and highly significant (r = 0.67, p < 0.001). Medical Research Council (MRC) grading did not predict strength (p > 0.54). CONCLUSIONS: IP-AMUNE is a good predictor of strength after nerve transfer surgery and should be considered in the evaluation and planning of patients undergoing nerve transfer to aid in donor nerve selection. SIGNIFICANCE: IP-AMUNE may significantly benefit those undergoing nerve transfer surgery for the restoration of movement.

A neurophysiological approach to nerve transfer to restore upper limb function in cervical spinal cord injury.

A successful nerve transfer surgery can provide a wealth of benefits to a patient with cervical spinal cord injury. The process of surgical decision making ideally uses all pertinent information to produce the best functional outcome. Reliance on clinical examination and imaging studies alone can miss valuable information on the state of spinal cord health. In this regard, neurophysiological evaluation has the potential to effectively gauge the neurological status of even select pools of anterior horn cells and their axons to small nerve branches in question to determine the potential efficacy of their use in a transfer. If available preoperatively, knowledge gained from such an evaluation could significantly alter the reconstructive surgical plan and avoid poor results. The authors describe their institution's approach to the assessment of patients with cervical spinal cord injury who are being considered for nerve transfer surgery in both the acute and chronic setting and broadly review the neurophysiological techniques used.

Use of Posterior Root-Muscle Reflexes in Peripheral Nerve Surgery: A Case Report.

It is well established that a mixed-agent general anesthetic regimen of volatile gas and intravenous anesthetic or total intravenous anesthetic (TIVA) is required to obtain adequate transcranial motor-evoked potentials (TcMEPs) to detect and hopefully prevent injury during brain, spinal cord, and peripheral nerve surgery. But even under ideal general anesthetic conditions, TcMEPs are not always detectable in every muscle monitored, and are prone to anesthetic fade, especially when neuropathic or injured tissue is monitored. TcMEP sensitivity to general anesthesia can be especially problematic during peripheral nerve surgery where there is often only one or a few essential muscles required to provide adequate monitoring; thus, maximum fidelity is essential. However, there is an anesthetic-resistant high-fidelity modality available to successfully monitor the motor component of distant peripheral nerves originating from the cauda equina. Percutaneus transabdominal electrical stimulation elicits a relatively anesthetic-resistant, robust motor response in muscles innervated by cauda equina nerve roots. We report the successful use of posterior root-muscle (PRM) reflex to monitor the decompression of the sciatic nerve at its bifurcation in a 22-year-old female with a history of severe sciatic nerve neuropathic pain and muscle weakness following benign thigh tumor resection.