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

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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. Based on the lead author's (R.K.N.) extensive experience with thousands of patients with brachial plexus and associated nerve injuries,^1-4 we have observed, using intraoperative neurophysiologic monitoring (IONM), that patients with scapular winging and shoulder dysfunction often experience simultaneous injuries to both UTBP and the LTN in the supraclavicular region because of their close anatomical proximity. The LTN arises from the upper portion of the cervical nerve roots C5, C6, and C7 of the brachial plexus. The diagnosis of winging scapula (WS) can be challenging.⁵ Most of the WS patients (87%)⁶ reported in the literature have medial winging due to LTN injury, serratus anterior muscle weakness, shoulder instability, and upper extremity (UE) functional disabilities.^1-9

In most WS patients, heavy weightlifting, sports, and recreationally related intense physical activities^1-4,10-14 appeared to cause injuries when the contractions of the middle scalene muscle directly compressed the UTBP and the LTN. IONM is used to assess the nerve's functions and monitor the immediate results of decompression and neurolysis, and it can predict surgical outcomes.¹⁵ Our study reports the first documented coincidence of UTBP and LTN injuries in patients with scapular winging and shoulder dysfunction. We show an upper trunk injury in patients whose preoperative electromyography (EMG) did not show injury to the UTBP.

Furthermore, we report that neurolysis of the UTBP and LTN immediately increases the nerve conduction in 4 UE muscles assessed intraoperatively, improving shoulder functions and decreasing the scapular winging with an average follow-up of 1.3 years after surgery.

We screened patients with traumatic brachial plexus and associated nerve injuries. The patient assessment included the demographics (sex, age) and medical history of all patients in this report. We 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 decreased shoulder movements who had neurolysis of the UTBP and LTN with the lead author and surgeon, R.K.N. Patients also had follow-up evaluations after surgery (a mean of 1.3 years; range 0.2 to 4.6 years) (Table 1). Pre- and intraoperative EMG, nerve conduction velocity, and the compound muscle action potential (CMAP) were measured for all 50 patients in this report. Winging of the scapula occurs in movements of forward elevation and abduction. On physical examination, severe WS is evident; however, mild to moderate WS patients are evaluated while they flex their arms horizontally and perform a wall push-up. Measurement of WS score and shoulder movements and surgeries were performed as reported in our previous publications (Figure 1).^1,2,4

Table 1: Patient Demographics and Improvements After Decompression and Neurolysis in 50 Patients With Scapular Winging and Decreased Shoulder Movements. M, male; F, female; L, left; R, right; ESW, extent of scapular winging.

Figure 1 illustrates the 4 classifications used to assess the extent of scapular winging (ESW): 1 denotes severe, 2 moderate, 3 mild, and 4 minimal/normal.

Statistical analyses

Excel 2013 was used to analyze and create graphs from descriptive statistical data. A student t test was used to assess whether the surgical improvement was statistically significant compared with the preoperative data. P values ≤.05 were considered significant.

We examined the association between the following parameters using the Pearson correlation coefficient: time to surgery and pre-and postoperative extent of scapular winging (ESW); time to surgery and pre-and postoperative active range of motion (AROM); pre- and postoperative ESW; pre- and postoperative AROM; follow-up time and postoperative ESW; follow-up time and postoperative AROM; and pre-and intraoperative CMAPs of the UE nerves tested.

All 50 patients in this report showed evidence of UTBP injury with biceps muscle strength scores of M3 or 4/5 before surgery. After surgery, IONM results 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; Figures 2-5). There was a strong correlation between the CMAPs of the 4 UE muscles before and after surgery (R = 0.6, 0.28, 0.59, 0.57, respectively; P < .0001; Table 2). Preoperatively, 28 patients (56%) had severe, 20 (40%) had moderate, and 2 (4%) had mild scapular winging. Postoperatively, scapular winging, shoulder flexion, and abduction improved significantly in 98% (n = 49) of the patients after an average surgical follow-up of 1.3 (range 0.2–4.6) years (Figure 6). All patients had below 170° (15° - <170°) AROM preoperatively. Postoperatively, AROM (forward flexion and abduction at the shoulder) improved significantly (mean 168° ± 11° and 165° ± 16°, respectively) compared with the preoperative mean of 127° ± 30° and 122° ± 29°, respectively (P < .0001; Figures 7–9).

Figure 2. Demonstrates a significant improvement in CMAPs of the serratus anterior following surgery during IONM (886 ± 937; P < .0001) when compared with the CMAPs (295 ± 291) before surgery. 

Figure 3. Shows a significant improvement in the supraspinatus CMAPs following surgery during IONM (618 ± 423; P <.0001) when compared with the CMAPs (237 ± 216) before surgery. 

Figure 4. Shows a significant improvement in the deltoid CMAPs after surgery during IONM (936 ± 1015; P <.0001) when compared with the CMAPs before surgery (344 ± 446). 

Figure 5. Demonstrates a significant improvement in CMAPs of the biceps after surgery during IONM (1109 ± 1230; P < .0001) when compared with the CMAPs (492 ± 656) before surgery. 

Table 2: Pearson Correlation Data. 

Figure 6. Demonstrates a significant improvement in scapular winging in 50 scapulas with severe to moderate winging before surgery. After a mean follow-up of 1.3 years, the average preoperative ESW score improved to 3.3 ± 0.8 (P < .0001), which was 1.5 ± 0.6 before surgery.

Figure 7. Indicates the surgical result of ESW and the time to injury do not significantly correlate (R = 0.02, P =.3).

Figure 8. Displays a linear association between pre- and postoperative shoulder forward flexion (R = 0.3, P < .0001). The overall improvement in shoulder flexion (mean 168° ± 11°) after surgery was statistically significant compared with the preoperative mean of 127° ± 30° (P < .0001). 

Figure 9. Depicts a linear association between pre- and postoperative shoulder abduction (R = 0.54, P < .001). The postoperative shoulder abduction (mean 165° ± 16°) was statistically significant compared with the preoperative mean of 122° ± 29° (P < 0.0001).

The relationship between the surgical outcomes and surgery delay was not significant (R = 0.02, P < .3; Table 2). Follow-up time was weakly associated with the surgical outcomes of ESW (R = -0.2) and AROM (R = 0.12; P < .001). The association between the CMAPs of all 4 muscles evaluated during IONM before and after surgery was moderate to strong: serratus anterior (R = 0.6), supraspinatus (R = 0.28), deltoid (R= 0.57), and biceps (R = 0.59; P < .001; Table 2)

Figure 10. A 29-year-old male patient with moderate WS and decreased shoulder AROM (shoulder flexion and abduction, 15° and 50°, respectively). (A) Preoperative image. (B) Postoperative image 3 months after surgery. Postoperative image shows a fully corrected scapula, no winging, and complete overhead movements of 180°.

Figure 11. A 34-year-old female patient with (A) severe scapular winging and (B) decreased shoulder abduction before surgery. Four months after surgery, the patient recovered (C) a normal scapula and (D)180° of shoulder abduction.

After surgery, no patient experienced a worsening of their preoperative symptoms.

Patients with winged scapula and decreased shoulder functional movements due to UTBP and LTN injuries can result in permanent impairment with pain that can limit patients' quality of life and daily tasks if untreated.^1,9 These patients have considerable difficulty and pain in abducting and flexing the arm at shoulder level.^1,2 In addition, severe scapular winging gives an abnormal shoulder appearance and posture, resulting in permanent cosmetic defects. Injuries can occur due to accidents/falls (acute) or repetitive overuse (chronic).¹⁰ Weightlifting or intense physical activity^11,14 was the cause of injury in 18 of 50 patients among the 10 causes in this report. Chronic compression and pressure on the nerve can damage the endoneurial capillaries and cause intraneural edema,¹⁶ which leads to axonal demyelination and malfunction of the internodal ion channels,¹⁷ and neural cell structures,¹⁸ followed by undesirable remyelination. Further, this impairs the transport of signaling molecules, thereby blocking the stimulation of muscle contraction.¹⁸

Nonsurgical interventions such as physical therapy, bracing, and pain control have been suggested to alleviate symptoms and maintain shoulder function.^9,12,13,19 However, no conservative management is universally accepted and effective.^9,20 Studies investigating bracing therapy¹⁹ have reported conflicting results and low patient compliance. Early detection and treatment can prevent a substantial loss of activity time or recurrence.²¹ Timely referrals are essential for patients who require surgical management, as muscles undergo atrophy if treatment is delayed.²¹ Early surgical intervention can result in a functional return.^22-27 In stubborn, symptomatic WS patients, late surgical alternatives such as arthrodesis, tendon, and free muscle transfers are critical.^{26 -29} According to recent findings from the Monte Carlo Stimulation,³⁰ indirect costs may be reduced if surgery and other interventions maximize patients' ability to return to work after severe brachial plexus and accessory nerve injuries.³¹

Neurolysis and surgical decompression are simpler, more physiologic, and less morbid than other surgeries, such as scapulothoracic fusion or pectoralis to scapula tendon transfers.² These nerve procedures relieve the source of nerve constriction, subsequently improving Na+/K+ ATPase activity and the action potentials to regenerate,¹⁷ allowing the nerve to restore muscle function rapidly.^2,18 Rapid functional recovery after decompression and neurolysis has been demonstrated.^2,32 Burton et al³² recently reported that patients with prominent scapular winging and pain recovered near-complete symptom-free, significantly improved function and returned to regular activity 3 months after decompression and neurolysis. Klifto and Dellon^33,34 have successfully demonstrated alleviating pain after neurolysis in diabetic patients.

Our present study is the first to report that decompression and neurolysis of the UTBP, in addition to the LTN, provide motor recovery to all 4 UE muscles (supraspinatus, biceps, deltoid, and serratus anterior) tested by IONM and significantly decreased WS and improved shoulder functional movements after a mean follow-up of 1.3 years. Reduced CMAP of the 4 UE muscles examined before surgery shows these patients had not only injuries to the LTN but also to the UTBP. CMAP decrease of 50% relates to muscle strength scores less than 3/5.³⁵

IONM monitors the immediate effects of neurolysis and predicts surgical outcomes based on CMAP results.^36,37 Alon and Riohkind^36,37 have demonstrated a significant improvement in CMAPs between the onset and completion of external and interfascicular neurolysis in peripheral-nerve injuries (PNIs). PNI is one of the most frequent complications during surgeries, yet the occurrence of PNI is low in studies that measure nerve conduction (CMAP) during surgeries.^17,36-38.

Typically, early nerve surgery is shown to provide a better outcome. However, studies have shown³⁹ no correlation between surgery delays and postoperative shoulder functional outcomes in nerve injury patients. Since the relationship between the time to surgery and the CMAPs during IONM was neutral and not significantly associated with the 4 UE muscles tested, 9 of our patients in this report who had significant functional deficits that had persisted for over 6 years improved remarkably after surgery. The duration of injury and the length of follow-up time had no significant impact on the surgical outcomes, as we and other investigators demonstrated that decompression and neurolysis rapidly improved shoulder functional movements.^2,32 A significant improvement in shoulder abduction was shown in WS patients who had neurolysis compared to nerve-grafting.⁴⁰ The effectiveness and low morbidity of nerve surgery make it the treatment of choice.

This is a single-center retrospective study.

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 and decompression of the LTN and UTBP immediately increased the nerve conduction to the UE muscles assessed intraoperatively. In addition, UE functional movements improved, and scapular winging decreased in 98% of the patients in a mean follow-up of 1.3 years.