Clinical Application of Ultrasound-guided Electrode Placement and Detection of Nerve Action Potential.

Background:  We explore a minimally invasive method (combined ultrasound detection, electrode placement and electrophysiologic nerve examination) to evaluate the early-stage quality of a nerve suture site.

Methods:  Ten patients with median and/or ulnar nerve injuries who had undergone nerve suture were recruited. Postoperative ultrasound examination found that the nerve injury was sutured. Then, a stimulating electrode and recording electrode were located beside the nerve proximal and distal to the suture site guided by ultrasound. Measurement of nerve action potentials (NAP) were performed with these electrodes, followed by surgical exploration. The pre- and intraoperative electrophysiologic findings were compared, together with amplitude, latency, and wave shape of NAP.

Results:  Of the 10 patients, 3 patients were diagnosed with median nerve injury, 2 with ulnar nerve injury, and 5 with the median nerve and ulnar nerve injury. NAP could not be detected pre- and intraoperatively in three median nerves from three patients and in two ulnar nerves from two patients. NAP was detected in 10 nerves from the remaining 5 patients. The pre- and intraoperative NAP results showed consistent results concerning the status of the nerve suture. Wilcoxon's signed-rank test indicated no significant difference in the amplitude and latency detected via sonographically placed electrodes and during surgical exploration. The number of negative-phase waves were equally distributed.

Conclusion:  Ultrasound-guided electrode placement and NAP detection can substitute surgery and serve as a minimally invasive approach to evaluate the regeneration of a sutured nerve.