Coincidence of Brachial Plexus Upper Trunk and Long Thoracic Nerve Injuries in 50 Patients With Winged Scapula: Improvements in Shoulder Stability and Functional Movements After Decompression and Neurolysis

Background: Injuries to the long thoracic nerve (LTN) and upper trunk of the brachial plexus (UTBP) can occur simultaneously and cause scapular winging and shoulder instability. The literature has not documented the concurrent occurrence of UTBP and LTN injuries in these patients. We show an upper trunk injury in patients whose preoperative electromyography (EMG) did not show injury to the UTBP.

Methods: We screened patients with traumatic brachial plexus injuries and associated nerve injuries and identified 50 patients (29 men and 21 women; 31 right side and 19 left side; mean age 34 years, range 16-63 years) with winged scapula and shoulder instability who had undergone neurolysis and decompression of the UTBP and LTN with the lead author and surgeon, R.K.N. We measured and compared the compound motor action potentials (CMAPs) of the upper limb nerves before and after neurolysis during intraoperative neurophysiological monitoring (IONM) and compared it with surgical outcomes.

Results: After surgery, IONM showed a significant increase in CMAPs for all 4 muscles: serratus anterior (295 ± 291 to 886 ± 937), supraspinatus (237 ± 216 to 618 ± 423), deltoid (344 ± 446 to 936 ± 1015), and biceps (492 ± 656 to 1109 ± 1230, P < .0001). The CMAPs of the 4 upper extremity (UE) muscles showed a positive correlation before and after surgery (R = 0.6, 0.28, 0.59, 0.57, respectively; P < .0001). Preoperatively, all patients had severe to moderate scapular winging and 15° - <170° in active range of motion (shoulder forward flexion and abduction). Scapular winging, shoulder flexion, and abduction improved significantly in 98% (n = 49) of the patients with a postoperative average of 168° ± 11° and 165° ± 16°, respectively, compared with the preoperative average of 127° ± 30° and 122° ± 29°, respectively, (P < .0001) with a mean follow-up of 1.3 years. Postoperatively, no patient experienced a worsening of their preoperative symptoms.

Conclusions: Our article presents the first documented occurrence of a long thoracic nerve injury coinciding with a brachial plexus upper trunk lesion in 50 patients with scapular winging whose preoperative EMG did not show injury to the UTBP. Neurolysis of the UTBP and LTN immediately increased the nerve conduction to the UE muscles evaluated intraoperatively.