Suprascapular Neuropathy
Abstract & Commentary
Synopsis: A unique functional outcome study evaluating electrodiagnostic studies and method of treatment for suprascapular neuropathy found pretreatment electromyographic findings were predictive of treatment response, with minimal EMG changes predicting a limited response to treatment and vice versa. Spinoglenoid notch cysts responded significantly better with an operative approach with arthroscopic and open surgery providing similarly good results. Overuse and viral neuritic etiologies should be treated nonoperatively.
Source: Antoniou J, et al. Suprascapular neuropathy. Variability in the diagnosis, treatment, and outcome. Clin Orthop. 2001;386:131-138.
This study by Antoniou and colleagues evaluated their results for treatment of suprascapular neuropathy seen among "all comers" to their Shoulder and Elbow Service. Fifty-three patients were evaluated at least 1 year from time of surgery (n = 36) or nonoperative treatment (n = 17). Etiologies included previous trauma, overuse, traction injuries, viral neuritis (Parsonage Turner Syndrome), 19 cases related to a spinoglenoid notch cyst, and 7 cases attributable to compression by the spinoglenoid ligament. Spinoglenoid notch cysts responded significantly better to operative treatment than to nonoperative treatment. Open and arthroscopic treatment of spinoglenoid notch cysts were equally effective. Electromyographic findings were evaluated and all patients underwent pre- and post-treatment EMGs (48 of 53 patients tested by the same neurologist, and all EMGs were read by the same neurologist, blinded to the individual patient outcome). Interestingly, EMG findings did not directly correlate to pretreatment function or score, but were partly predictive of functional outcome after treatment, especially in the presence of a spinoglenoid notch cyst. More severe EMG changes were associated with significant functional improvement after treatment of the nerve lesion. Antoniou et al note that traditional nonoperative treatment is advisable for all types of suprascapular nerve palsies and recommend nonoperative measures as the definitive treatment for traction lesions, repetitive overuse nerve lesions, and viral neuritis etiologies. Spinoglenoid notch cysts and compressive neuropathies responded significantly better to operative treatment than to nonoperative treatment.
Comment by Robert C. Schenck, Jr., MD
This useful clinical study is an excellent assessment of a large series of patients treated for a problem only seen occasionally in a sports medicine practice. The suprascapular nerve enters the posterior aspect of the shoulder passing beneath the transverse scapular ligament (with the suprascapular artery and vein passing over the ligament), then innervates the supraspinatus.1 As the neurovascular bundle travels distally, it passes through a narrow fibro-osseous tunnel formed by the spine of the scapula and the spinoglenoid ligament. As seen with the study by Antoniou et al, spinoglenoid notch cysts show normal EMG activity of the supraspinatus in most cases; whereas patients with viral neuritis or traumatic etiologies had involvement of both the supraspinatus and infraspinatus with varied severity. What I find in my clinical practice is underlined in the following statement by Antoniou et al, "In the case of the ganglion cyst at the spinoglenoid notch, the cause of the cyst (labrum tear) may be more important as a cause of pain than the EMG findings. Careful evaluation and treatment of all other intraarticular and extraarticular disease is recommended." With spinoglenoid notch cysts, treatment of the labral pathology (most commonly a SLAP tear) is as important as aspiration or removal of the cyst, and should be performed simultaneously.
Reference
1. Cummins CA, et al. Current concepts review. Suprascapular nerve entrapment. J Bone Joint Surg Am. 2000;82-A(3):415-424.
Dr. Schenck, Jr., Deputy Chairman, Department of Orthopaedics, University of Texas Health Science Center, San Antonio, TX, is Associate Editor of Sports Medicine Alert.
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