Supra-scapular nerve neuropathy in combination with massive ruptures of the rotator cuff: clinic, diagnosis, treatment. An overview of modern concepts.

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Introduction. Shoulder joint pain is a very common problem of the musculoskeletal system. Complaints of pain directly related to the shoulder joint are most often associated with damage to the bone and cartilage structures of the shoulder joint itself, the acromioclavicular joint, the sternoclavicular joint, as well as the rotator cuff and other soft tissues of the shoulder complex [1, 2]. Thus, according to some studies, it has been proven that 20-40% of patients have asymptomatic ruptures of the rotator cuff, which suggests that structural pathology may not always manifest itself clinically, as well as impair the function of the shoulder joint [3, 32]. Over the past 30 years, many scientific articles have been published on the occurrence, causes, risk factors, and possible options for conservative and surgical treatment of supra-scapular nerve neuropathy in combination with massive rotator cuff rupture, but there is no consensus on treatment tactics, according to the literature.

Materials and methods. The literature was searched using the PubMed database headers. This review includes publications on the topic "supra-scapular nerve neuropathy" from the time of writing to 2024. The inclusion criteria were the availability of data on supra-scapular nerve neuropathy in combination with rotator cuff tears, the results of surgical treatment of this pathology in the form of arthroscopic decompression of the supra-scapular nerve in combination with rotator cuff suture. The key words in choosing the studies were the search queries: "supra-scapular nerve", "supra-scapular nerve neuropathy", "supra-scapular tenderloin" and "spinoglenoidal tenderloin", "arthroscopic decompression (release) of the supra-scapular nerve", "massive ruptures of the rotator cuff of the shoulder".  The main subject of the study was the assessment of the current state of the clinic, diagnosis and treatment of supra-scapular nerve neuropathy in combination with massive ruptures of the rotator cuff of the shoulder. A total of 46 publications were found, but only 9 of them described the results of surgical treatment of supra-scapular nerve neuropathy in combination with massive ruptures of the rotator cuff of the shoulder. The analysis of the main results of surgical treatment based on clinical results was carried out.

Relevance. According to a number of researchers [1, 4], it was claimed that the incidence of general morbidity in patients with shoulder pain ranged from 0.9 to 2.5%, with an average incidence of 30.3 cases [1, 4, 5, 6]. The prevalence of diseases associated with pathology of the shoulder joint and rotator cuff is generally higher in women (15-26%) than in men (13-18%) [1, 7]. Pathology of the supracapular nerve has recently become one of the common causes of pain and weakness in the shoulder joint [32]. Recent clinical studies have suggested that signs of supra-scapular nerve neuropathy occurred in 30% of patients with massive rotator cuff tears and contributed to the development of pain syndrome and muscular atrophy [14].

Anatomy. The description of supra-scapular nerve compression syndrome should nevertheless begin with an understanding of the corresponding anatomy. The supra-scapular nerve is mixed, formed by branches of the upper trunk of the brachial plexus (Fig. 1) [15]. It enters the supraclavicular notch of the scapula under the upper transverse scapular ligament. This is the first anatomical site of possible nerve compression [16]. Next, the nerve enters the supraspinatus fossa [17]. In the supraspinatus, branches branch off from the supraspinatus nerve to the capsule of the shoulder joint, the supraspinatus muscle, and the acromioclavicular joint, then encircle the base of the scapula and enter the subacute fossa, innervating the subacute muscle (Fig. 2) [12]. The presence of anatomical variations of the supra-scapular notch (Fig. 3) can cause a narrowing of the space in which the nerve passes, making it vulnerable to compression [19, 20].

Pathophysiology. Pain and restriction of movement and, as a result, dysfunction of the shoulder joint can be associated not only with ruptures of the rotator cuff of the shoulder, but also with pathology of the supra-scapular nerve [8, 9, 10, 11]. Nerve compression is possible with fractures of the scapula, in the presence of additional formations: soft and bony formations such as lipomas and intraosseous ganglion cysts [22, 23]. Currently, much attention is being paid to the possible relationship between supra-scapular neuropathy and rotator cuff tears with significant fiber retraction. Albritton and co-authors in their study [24] noticed that medial retraction of the supraspinatus tendon dramatically increases nerve tension. Although it has been established that there is a tension limit during lateralization of the supraspinatus and subclavian muscles during the suture of the rotator cuff of the shoulder, as this can lead to excessive tension of the branches of the supra-scapular nerve [25].  There are also suggestions that there is a connection between an increased range of motion in the shoulder joint and isolated weakness of the scapular muscle [26, 27]. 

Clinical manifestations and physical examination. The clinical picture of neuropathy often depends on the location and causes of compression of the supracapular nerve [13, 14, 19]. However, upon careful examination and interview of patients, it is possible to establish that the pain is localized in the scapula area, increases when the shoulder is brought with internal rotation, or when bending at the shoulder joint, or when turning the head in the opposite direction [35]. Palpation of the supraspinatus fossa can be sharply painful, positive stretching tests are determined [36] and the Planchet test[37].At the same time, it is worth paying attention to the condition of both shoulders: in case of supraspinatus nerve neuropathy, pronounced hypotrophy of the supraspinatus and subclavian muscles is observed, compared with the healthy side (Fig. 4). Compression of the nerve in the supraspinatus tenderloin can lead to a loss of more than 75% of force during abduction and external rotation [33, 35]. Compression of the supracapular nerve in the area of the spinoglenoid notch manifests itself as isolated hypotrophy of the subclavian muscle and does not cause pain [34]. Differential diagnosis should be performed with radiculopathies of the C5 level of the cervical spine, with spinal muscular amyotrophy, as well as secondary neuropathies [37].

Exam. If supra-scapular neuropathy is suspected, standard radiography should be performed first to exclude bone pathology. The literature describes a "Stryker's supra—scapular tenderloin" (Fig. 5). This is a special image for assessing the supra-scapular tenderloin and spinoglenoidal tenderloin, which should be included in the X-ray examination [38]. If necessary, it is worth performing a CT scan, which can be useful for detecting bone damage or anatomical features that can compress a nerve. The gold standard of the study is an MRI scan, as the most accurate way to identify bulky formations. It allows you to assess changes (damage) in the muscles of the rotator cuff of the shoulder, the degree of retraction of damaged tendons, and identify hypotrophy/atrophy of the supraspinatus and subclavian muscles. This method also makes it possible to assess the degree of fatty degeneration, the presence of additional formations in the supraspinatus and spinoglenoidal notch of the scapula [35]. With an MRI scan, you need to look for three main signs. These are edema, the degree of damage, and fatty degeneration of the muscles. Edema of the supraspinatus and subclavian muscles is a pathognomonic sign of supra-scapular neuropathy. Pronounced retraction according to Patta 2-3 (Fig. 6), fatty degeneration according to Gutalle 3 (Fig. 7), the presence of fluid formations in the supraspinatus notch of the scapula (Fig. 8) may indicate compression of the supracapular nerve [39]. Neuropathy can be detected as a few days after injury or, in some cases, when abnormalities appear on electromyography (ENMG). An important aspect of the diagnosis of neuropathy, which makes it possible to determine the level of damage, is to conduct an ENMG study. The main symptom of peripheral neuropathy is an increased delay in motor impulse and signs of denervation in the form of fibrillation and sudden waves. However, with long-term neuropathic shoulder pain, ENMG data give negative results [36]. This may be due to the fact that the method does not allow detecting damage to smaller fibers, or to a part rather than the whole nerve.

Treatment. The origin of neuropathy itself, as well as its combination with other pathological changes in the shoulder joint, are the most important factors in choosing the appropriate treatment [36]. There is no consensus on where to start treatment. Most authors are inclined to believe that neuropathy treatment should be started without surgery, unless nerve compression is caused by a tumor or a scapula fracture [38]. If conservative treatment does not help, surgical decompression of the supracapular nerve is recommended.  However, the optimal duration of nonoperative treatment remains unclear [40]. If there is no muscle atrophy, there are no obvious changes on the ENMG, there are no signs of lip rupture or ganglion cyst, but weakness and pain are present, a 6-month course of non-surgical treatment is recommended before considering the possibility of surgery. Literature data indicate that conservative treatment often gives unsatisfactory results in patients with symptoms lasting more than six months, as well as in patients with severe muscle hypotrophy and atrophy, as well as with bulky lesions and extensive ruptures of the rotator cuff. The reasons why patients' condition improves with conservative treatment have not been precisely established, most likely it may be due to compensatory mechanisms of other muscles of the shoulder girdle [38].

Surgical treatment. Indications for surgical treatment are nerve compression by bulky formations, massive ruptures of the rotator cuff of the shoulder and the ineffectiveness of conservative treatment [38]. It has been proven that in patients with a supra-scapular nerve compressed by soft tissues, surgical treatment gives the best results, and, if possible, arthroscopic intervention should be preferred over open methods [13,36]. According to modern concepts, arthroscopic intervention itself is the gold standard for the treatment of supra-scapular nerve neuropathy [41, 42, 43, 44, 45, 46], as well as the treatment of concomitant pathology of the rotator cuff of the shoulder [47, 48, 49].. Results. According to modern publications, there is no clear answer to the question of whether arthroscopic decompression is indicated for patients with massive ruptures of the rotator cuff. Previously, improvements in functional parameters were reported in patients with massive ruptures of the rotator cuff in combination with arthroscopic release of the supracapular nerve. L.Lafosse [36] analyzed the results of arthroscopic decompression in a series of 10 patients and found improvements in condition and function in all patients. Costuros et al. reported on six patients with neuropathy associated with extensive rotator cuff rupture. He found sustained improvement in function in four patients and partial recovery in two [50]. In the study by Shah et al., 21 out of 24 (87.5%) patients had deep pain in the back of the shoulder and supracapular nerve neuropathy according to the ENMG. After decompression of the supra-scapular nerve, 17 out of 24 (71%) of these patients had decreased pain intensity and improved ASES scores 9 weeks after surgery [51]. However, in a previously unpublished series of 75 patients with extensive rotator cuff rupture who underwent rotator cuff repair surgery, L.Lafosse [36] identified concomitant supra-scapular nerve neuropathy in 29 (39%) patients with ENMG before surgery.  In this group, there were no statistically significant differences between patients with nerve release and those without it. Colin and co-authors [14], as well as Yang [41] and co-authors reported that in groups with arthroscopic release of the supracapular nerve in combination with suture of massive ruptures of the rotator cuff of the shoulder, there was no statistically more significant decrease in pain syndrome, assessed on a visual analog scale, compared with the group without it. In addition, there was no significantly more pronounced improvement on the UCLA scale in the decompression group compared to the group without it. In addition, there were no significant differences between the two groups in terms of continuous assessment and frequency of discontinuities. The study data also confirmed that the incidence of supra-scapular nerve neuropathy in patients with ruptures of the posterior part of the rotator cuff is 8.7%. Sachinis and co-authors [46] conducted a randomized controlled trial to find out whether rupture repair alone can be a successful treatment method even in patients with established supra-scapular nerve neuropathy. They found no significant differences in improving shoulder function between eliminating the rotator cuff tear directly and eliminating the tear with an additional option in the form of a supracapular nerve release. In addition, their study also showed that shoulder function is inversely proportional to fat infiltration on the subscapular muscle, which may occur secondarily in relation to supra-scapular nerve neuropathy. A study by K.Yamakado [43] of 31 cases of supra-scapular nerve neuropathy in combination with rotator cuff tears did not reveal a significant difference between the two groups in all measurements at the final follow-up: UCLA scores and VAS scale data did not make up a statistically significant difference in the 2 comparison groups. However, the results showed that arthroscopic release of the supra-scapular nerve, in addition to arthroscopic tendon repair, eventually leads to recovery, improving the condition compared to preoperative. Thus, it can be established that most publications describe the absence of a statistically significant difference in the clinical results of rotator cuff reconstruction with and without arthroscopic release procedure.

Conclusion. Supra—scapular nerve neuropathy is an increasingly common pathology of the shoulder joint. However, the diagnostic search remains a difficult task, requiring not only a thorough medical history and physical examination, but also the use of appropriate research methods. Timely diagnosis is of paramount importance, as chronic diseases have worse prognoses than acute lesions. Isolated compression should primarily be treated conservatively, while a combination of supra-scapular nerve neuropathy and massive rotator cuff tears often requires immediate surgical treatment. Despite the obvious connection between the pathology of the supracapular nerve and the retraction of the rotator cuff, the role of arthroscopic decompression of the supracapular nerve during recovery is still controversial.  In conclusion, it should be noted that the currently published studies provide some evidence of a link between supra-scapular nerve compression syndrome and massive rotator cuff tears and indicate good postoperative results, but ultimately provide mixed data. Further studies on larger patient populations are required.

About the authors

Oksana Ushkova

Family Medicine Clinic "Eucalyptus", Voronezh

Author for correspondence.
Email: ushkovaoksana@yandex.ru
ORCID iD: 0009-0003-0641-4351

orthopedic traumatologist, Trauma department

Russian Federation

Sergei Yu. Dokolin

Vreden National Medical Center for Traumatology and Orthopedics

Email: sdokolin@gmail.com
ORCID iD: 0000-0003-1890-4342
SPIN-code: 1993-2304

MD, Dr. Sci. (Med.)

Russian Federation, Saint Petersburg

Vladislava I. Kuzmina

Vreden National Medical Center for Traumatology and Orthopedics

Email: tasha_777@bk.ru
ORCID iD: 0000-0001-7866-5545

врач травматолог ортопед

Санкт-Петербург

Andrei M. Shershnev

Vreden National Medical Center for Traumatology and Orthopedics

Email: andreyshersh@gmail.com
ORCID iD: 0000-0001-6623-2144

врач травматолог ортопед

Санкт-Петербург

References

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