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Role of Electromyography and Intraoperative Nerve Stimulation in Isolated Long Thoracic Nerve Palsy
Shelley Suzanne Noland, MD1; Emily M. Krauss, MD; MSc2; John M Felder, MD2; Susan E. Mackinnon, MD2
1Mayo Clinic Arizona, Phoenix, AZ, 2Washington University, St. Louis, MO
Introduction: Electromyography is unreliable in guiding the management of isolated long thoracic nerve palsy. Optimal management depends on history, physical examination, and intraoperative nerve stimulation of the long thoracic nerve.
Materials & Methods: 19 patients who required surgery for an isolated long thoracic nerve palsy were reviewed retrospectively. Preoperative demographics, electromyography, and physical examinations were reviewed. Intraoperative nerve stimulation, surgical decision-making, and postoperative outcomes were reviewed.
Results: 19 patients with an average age of 32 were included in the study. All patients had an isolated long thoracic nerve palsy cause by either an injury (58%), Parsonage-Turner syndrome (32%), or shoulder surgery (10%). 18 patients (95%) underwent preoperative electromyography, 10 with evidence of denervation (56%). 13 patients had motor unit potentials in the serratus anterior (72%). Intraoperative nerve stimulation was performed on all patients and intervention was based upon these results. The preoperative EMG did not correlate with intraoperative nerve stimulation in 13 patients (72%) and did correlate in 5 patients (28%). 3 patients had a nerve transfer (3 thoracodorsal to long thoracic at lateral chest, 1 pec to long thoracic at supraclavicular incision). In the 15 patients who had decompression alone, there was return of full forward flexion of the shoulder in 11 patients (73%) at average of 3.3 weeks. In the 3 patients who had a nerve transfer, there was return of full forward flexion of the shoulder at average of 2.5 months.
Conclusions: The preoperative EMG is unreliable in determining whether there is a conduction block in patients with isolated long thoracic palsy. A treatment algorithm based on intraoperative nerve stimulation will help guide surgeons in their clinical decision making in patients with isolated long thoracic nerve palsy (Figure 1). Intraoperative nerve stimulation is the gold standard in the management of isolated long thoracic nerve palsy.
Figure 1. Surgical decision-making algorithm in isolated long thoracic nerve palsy.
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