Intraoperative electroneurodiagnostics (transcranial electrical motor evoked potentials) to evaluate the functional status of anterior spinal roots and spinal nerves during brachial plexus surgery.

Intradural spinal root lesions cannot be recognized by dissecting the brachial plexus and lead to ineffective surgery if they remain undetected. Therefore, patients need to undergo a diagnostic procedure to assess the intradural status of the spinal roots. Although motor recovery is the main goal of brachial plexus surgery, the techniques currently applied do not permit adequate evaluation of the anterior root. In search of an alternative, we performed intraoperative motor evoked potentials. Ninety spinal nerves in 19 patients suffering from brachial plexus lesions were dissected. Twenty-seven spinal nerves were avulsed; 8 nerves were disrupted and 17 were completely scarred, resulting in 25 stumps. Thirty-eight nerves appeared to be undamaged. On central stimulation, nerve compound action potentials were recorded from the exposed spinal nerves. Nerve compound action potentials could only be recorded from 21 stumps and from 32 apparently undamaged nerves. No recordings were obtained from 4 stumps and 7 spinal nerves in continuity. According to these findings, it is highly probable that surgery would have been insufficient in 10 spinal nerves if intraoperative motor evoked potentials had not been performed. We conclude that (1) intraoperative motor evoked potentials are an effective means for investigating the functional status of anterior motor roots and motor fibers in exposed spinal nerves, and (2) the use of motor evoked potentials should be considered during brachial plexus surgery to improve interventions.