Neuropathy of the suprascapular nerve and massive rotator cuff tears: a prospective electromyographic study

doi:10.1016/j.jse.2013.07.039

Journal of Shoulder and Elbow Surgery

Volume 23, Issue 1, January 2014, Pages 28-34

https://doi.org/10.1016/j.jse.2013.07.039 Get rights and content

Background

An association between massive rotator cuff tear (RCT) and suprascapular nerve neuropathy has previously been suggested. The anatomic course of the suprascapular nerve is relatively fixed along its passage. Thus, injury to the nerve by trauma, compression, and iatrogenic reasons is well documented. However, the association between retraction of the RCT and development of neuropathy of the suprascapular nerve remains unclear.

We aimed to prospectively evaluate the suprascapular nerve for preoperative neurodiagnostic abnormalities in shoulders with massive RCT.

Methods and materials

A prospective study was performed in 2 centers. Fifty patients with retracted tears of both supraspinatus and infraspinatus were evaluated. This was confirmed with preoperative computed tomography arthrography, and the fatty infiltration of the affected muscles was graded. Forty-nine preoperative electromyograms were performed in a standardized fashion and the results analyzed twice.

Results

Of 49 shoulders, 6 (12%) had neurologic lesions noted on electromyography: 1 suprascapular nerve neuropathy, 1 radicular lesion of the C5 root, 1 affected electromyogram in the context of a previous stroke, and 3 cases of partial axillary nerve palsy with a history of shoulder dislocation. No difference or diminution of the latency or amplitude of the electromyographic curve was found in the cases that presented significant fatty infiltration.

Conclusion

This study did not detect a suprascapular lesion in the majority of cases of massive RCT. With a low association of neuropathy with massive RCT, we find no evidence to support the routine practice of suprascapular nerve release when RCT repair is performed.

Section snippets

Patient selection

Between January 2008 and January 2009, all patients who were seen for massive RCT by the authors were considered potentially eligible for inclusion in this prospective multicentric study. All patients gave a written approval according to the ethical approval agreement. The inclusion criteria were patients (1) aged 65 years or younger, (2) without previous history of shoulder surgery, (3) with a massive RCT, and (4) with a tendon retraction of grade ≥II according to Patte assessed by CT

Results

During the study period, 50 patients met the inclusion criteria. One declined to participate. Thus, 49 EMG/NCS evaluations in 49 patients were performed. The study group was composed of 28 men and 21 women with a mean age of 56.2 years (range, 45.2 to 65.4 years). Thirty-eight patients had combined supraspinatus and infraspinatus tears, and 12 had an associated subscapularis tear. A fatty infiltration of stage 2 or greater was noted on CT arthrograms in 32 patients with supraspinatus tears and

Discussion

The current study demonstrated a low prevalence (2%) of SSNN, as defined by EMG/NCS, in a population of massive RCTs and seems to confirm the results of Vad et al,²⁸ who looked at 25 patients with RCT and clinical atrophy and found that only 2 patients (8%) had isolated SSNN. Contrarily, the rest of the published literature suggests that SSNN has a more frequent occurrence in the setting of massive RCT.8, 10, 15, 31 In the study of Boykin et al,⁶ 43% of electromyograms showed abnormalities, and

Conclusion

An electromyographic study did not detect a suprascapular lesion in the majority of cases of massive RCT. With a low association of neuropathy with massive RCT, there is no support for routine suprascapular nerve release when RCT repair is performed.

Disclaimer

The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

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Cited by (52)

Does suprascapular nerve release provide additional benefits for rotator cuff repair: a systematic review and meta-analysis
2022, Journal of Shoulder and Elbow Surgery
Citation Excerpt :
Therefore, SSNR may not be necessary to prevent SSN injury during the repair of massive RCT. Collin et al4 and Vad et al31 reported a low prevalence (2%) of SSN neuropathy in a population with massive RCT. Yang et al36 had confirmed the incidence of SSN neuropathy in patients with posterosuperior rotator cuff tears to be 8.7%.
There is still a lack of consensus regarding whether suprascapular nerve decompression should be routinely performed with rotator cuff repair. Therefore, this meta-analysis aimed to evaluate whether additional suprascapular nerve release (SSNR) could improve shoulder functional outcomes and pain relief more than rotator cuff repair alone.
We performed a literature review of electronic databases for noncomparative and comparative studies investigating the effect of SSNR in patients undergoing rotator cuff repair. The primary outcome was the change in shoulder function scores from the preoperative status, and the secondary outcome was the change in the visual analog scale (VAS) score of pain after surgery. A subgroup analysis was conducted based on the study design (noncomparative studies vs. comparative studies).
Nine studies comprising 279 participants were included. Our analysis demonstrated that the group that underwent SSNR had a better shoulder functional score after surgery than at preoperative assessment (standardized mean difference [SMD], 1.333, 95% confidence interval [CI], 0.708-1.959). No significant differences were identified in shoulder function improvement between those with and without SSNR, with an SMD of 0.163 (95% CI, −0.091 to 0.418). Likewise, the group with SSNR showed a decreased VAS score after surgery compared to their preoperative status (SMD, 0.910; 95% CI, 0.560-1.260). However, there was no significant difference in VAS change between those with and without SSNR, with an SMD of 0.431 (95% CI, −0.095 to 0.956).
The present meta-analysis revealed that SSNR might not be routinely needed in rotator cuff tendon repair as no additional benefits in functional improvement or pain relief were identified compared to rotator cuff tendon repair alone.
Aging Aggravates the Progression of Muscle Degeneration After Rotator Cuff Tears in Mice
2022, Arthroscopy - Journal of Arthroscopic and Related Surgery
Citation Excerpt :
Liu et al.20 reported that muscle atrophy can occur with tendon resection alone, but that muscular fatty infiltration and fibrosis cannot be induced without muscle denervation in young mice. However, whether the suprascapular nerve is damaged in humans after RCT still remains controversial.23-25 Given that RCT is a common injury in elderly patients and that muscle degeneration can be effectively induced in aged mice, as shown in the present study, it would be rational to use aged, but not young, animals to study the pathology of muscular fatty infiltration after RCT.
The purpose of this study was to evaluate the impact of aging on muscle degeneration after rotator cuff tear (RCT) in mice.
Young (12-week-old) and aged (50-to-60-week-old) female C57BL/6 mice were used (n = 29 for each group). The rotator cuff was transected, and the proximal humerus was removed to induce degeneration of the rotator cuff muscles. The mice were euthanized 4 and 12 weeks after the procedure (referred to as RCT-4wk mice and RCT-12wk mice, respectively) and compared with the sham-treated mice. The supraspinatus muscles were collected for histology, Western blot analysis, and gene expression analyses.
There was a significant increase in fat tissue in aged RCT-4wk mice (P = .001) and aged RCT-12wk mice (P < .001) compared with sham-treated aged mice, and aged RCT-12wk mice had a significantly increased fat area ratio compared with aged RCT-4wk mice (P < .001). The fat area was significantly larger in both the aged RCT-4wk (P = .002) and RCT-12wk mice (P < .001) than in the corresponding young mice. Muscular fibrosis was significantly increased in aged RCT-12wk mice compared with aged sham-treated mice (P = .005) and young RCT-12wk mice (P = .016). There were also significant increases in the expression of perilipin and transcripts of adipogenic and fibrogenic differentiation markers in aged RCT mice compared with young RCT mice.
The present results show that aging is critically involved in the pathology of muscular fatty infiltration and fibrosis after RCT, and muscular degeneration progresses over time in aged mice.
Aging promotes the progression of muscle degeneration in a mouse RCT model. Furthermore, this study shows that muscle degeneration occurs in aged mice even without denervation and that the model described in the present study is a useful tool for studying the pathology of muscle degeneration.
Suprascapular nerve decompression in addition to rotator cuff repair: a prospective, randomized observational trial
2020, Journal of Shoulder and Elbow Surgery
Tear and retraction of the supraspinatus (SS) and infraspinatus (IS) musculotendinous units and/or their repair may be associated with traction damage to the suprascapular nerve, potentially responsible for pain or weakness of the rotator cuff (RC). Arthroscopic release of the transverse scapular ligament at the suprascapular notch has been advocated to prevent or treat suprascapular nerve impairment associated with RC retraction and/or repair. The effect of this procedure on preoperative normal nerve function is, however, not well studied.We hypothesize that (1) decompression of the suprascapular nerve without preoperative pathologic neurophysiological findings will not improve clinical or imaging outcome and (2) suprascapular decompression will not measurably change suprascapular nerve function.
Nineteen consecutive patients with a magnetic resonance arthrography documented RC tear involving SS and IS but normal preoperative electromyography (EMG)/nerve conduction studies of the SS and IS were enrolled in a prospective, controlled trial involving RC repair with or without suprascapular nerve decompression at the suprascapular notch. Nine patients were randomized to undergo, and 10 not to undergo, a decompression of the suprascapular nerve. Patients were assessed clinically (Constant score, mobility, pain, strength, subjective shoulder value), with magnetic resonance imaging and neurophysiology preoperatively and at 3- and 12-month follow-up.
There was no clinically relevant difference between the release and the non-release group in any clinical parameter at any time point. At magnetic resonance imaging, there was a slightly greater increase of fatty infiltration of the IS in the release group without any other differences between the 2 groups. Electromyographically, there were no pathologic findings in the non-release group at any time point. Conversely, 3 of the 9 patients of the release group showed pathologic EMG findings at 3 months, of whom 2 had recovered fully and 1 only partially at 12 months.
In the presence of normal EMG findings, suprascapular nerve release added to arthroscopic RC repair is not associated with any clinical benefit, but with electromyographically documented, postoperative impairment of nerve function in 1 of 3 cases. Suprascapular nerve release does not therefore seem to be justified as an adjunct to RC repair if preoperative EMG findings document normal suprascapular nerve function. Based on these findings, the ongoing prospective randomized trial was terminated.
Preoperative Issues With Rotator Cuff Surgery
2020, Complications in Orthopaedics: Sports Medicine
Influence of a nerve injury proximal to the suprascapular nerve on healing of repaired rotator cuff tear
2020, Journal of Orthopaedic Science
Massive rotator cuff tears have a high rate of re-injury because of severe fatty infiltration. Our data showed that injuries proximal to the suprascapular nerve may be one cause of massive rotator cuff tears. The purpose of this study was to evaluate, using a rat model, how brachial plexus injury associated with a massive rotator cuff tear influences healing of the rotator cuff repair.
Seventy Sprague–Dawley rats were divided into three groups: rotator cuff tear with BP injury (DT group) (n = 28), rotator cuff tear without brachial plexus injury (T group) (n = 28), and a sham-operated group (n = 14). In the DT group, the rotator cuff tear was made and repaired 4 weeks after brachial plexus ligation. The gross assessment (evaluated the wet weight), biomechanical testing (evaluated the yield stress and the Young's modulus) and histological analyses (using the Bonar scale) were performed at baseline in the sham group, and at 4 and 12 weeks postoperatively in the DT and T groups (n = 7/group/time).
Mean wet weight and yield stress were significantly lower in the DT group than in the T group. Additionally, the mean Young's modulus was significantly higher in the DT group than in the T group. Histologically, greater tendon degeneration was observed around the musculotendinous junction in the DT group than in the T group.
The gross, biomechanical and histological data show that the repaired rotator cuff tendon with brachial plexus injury in rats does not heal as well as a repaired tendon without an accompanying brachial plexus injury. This suggests that more proximal neuropathy is one risk factor for re-tear of a repaired rotator cuff tendon.
Histological analysis and biomechanical evaluation of fatty infiltration after rotator cuff tear and suprascapular nerve injury in a rat model
2018, Journal of Orthopaedic Science
Rotator cuff tears are the most common shoulder injury, and little is known about the underlying etiology of fatty infiltration after rotator cuff tear. Previous studies speculated that rotator cuff tears lead to neural injury due to tethering of the suprascapular nerve at the notch. This study aimed to evaluate fatty infiltration after suprascapular nerve injury and rotator cuff tears.
Ninety adult male Sprague–Dawley rats were used and were divided into four groups: sham, tendon transection only, suprascapular nerve ligation, and tendon transection plus suprascapular nerve ligation. The suprascapular nerve injury models were created by tying the suprascapular nerve. At 2, 4, and 8 weeks postoperatively, histological analysis and biomechanical testing were performed to evaluate fatty infiltration and elastic change in the supraspinatus muscles.
The amount of fatty infiltration in the supraspinatus muscle was significantly higher in both the suprascapular nerve ligation and tendon transection plus suprascapular nerve ligation groups than in the tendon transection only group at 2, 4, and 8 weeks. The ultimate failure load and tensile strength were significantly different among the tendon transection only, suprascapular nerve ligation, and tendon transection plus suprascapular nerve ligation groups at 8 weeks postoperatively. Furthermore, the mean Young's modulus of the muscle was significantly greater in the tendon transection plus suprascapular nerve ligation group than in both the tendon transection only and suprascapular nerve ligation groups at 8 weeks postoperatively.
In this study, based on the results of histological and biomechanical examinations in our rat models, the etiology of fatty infiltration after massive rotator cuff tear might be different from the suprascapular nerve injury.

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ShoulderNeuropathy of the suprascapular nerve and massive rotator cuff tears: a prospective electromyographic study

Background

Methods and materials

Results

Conclusion

Section snippets

Patient selection

Results

Discussion

Conclusion

Disclaimer

J Shoulder Elbow Surg

J Shoulder Elbow Surg

Arthroscopy

J Shoulder Elbow Surg

J Orthop Res

Arthroscopy

J Shoulder Elbow Surg

J Shoulder Elbow Surg

J Shoulder Elbow Surg

Exp Neurol

Suprascapular neuropathy after intensive progressive resistive exercise: case report

Arch Phys Med Rehabil

Suprascapular neuropathy. Variability in the diagnosis, treatment, and outcome

Clin Orthop Relat Res

Nerve injuries about the shoulder in sports

J Bone Joint Surg Am

Axillary nerve palsy following blunt trauma to the shoulder region: a clinical and electrophysiological review

J Neurol Neurosurg Psychiatry

Neural cell adhesion molecule (N-CAM) accumulates in denervated and paralyzed skeletal muscles

Proc Natl Acad Sci U S A

Shoulder
Neuropathy of the suprascapular nerve and massive rotator cuff tears: a prospective electromyographic study