Extrinsic compression or traction on the suprascapular nerve by various sources can result in suprascapular neuropathy.7 Ganglion cysts occurring at the spinoglenoid notch can cause extrinsic compression of the suprascapular nerve,5 as the fixed position of the suprascapular nerve combined with the close proximity of the rotator cuff muscles make the nerve susceptible to compression by even small cysts. These ganglia may develop when labral or capsular tears allow synovial fluid to be forced into the tissues, creating a one-way-valve effect. A similar mechanism, by which meniscal tears lead to meniscal cysts of the knee, has been widely accepted and has led to the belief that many shoulder ganglion cysts are the direct result of a capsulolabral injury.18
These ganglion cysts tend to be painful and often can present with neurologic symptoms (ie, nerve compression causing pain and weakness). Ganglion cysts that present with suprascapular neuropathy are treated most effectively with decompression and subsequent evaluation of the glenoid labrum. Although traditional therapy has involved open surgical excision,3,11,12,15-17 the association of ganglion cysts with labral tears has made arthroscopic treatment of ganglion cysts increasingly more common, as it facilitates labral repair.2 Some investigators have suggested that repair of the glenoid labrum may be indicated in greater than ⅔ of patients with spinoglenoid cysts.1,13,18 Surgeons have anecdotally noted similar outcomes in patients having spinoglenoid notch cyst (SGNC) decompression or SGNC decompression with labral repair. Others have suggested that arthroscopic treatment of these ganglion cysts is preferable to open treatment4 because the arthroscopic approach obviates the need for taking down the deltoid origin or splitting the fibers of the infraspinatus muscle during the operative approach. In addition, arthroscopic treatment of ganglion cysts shares the same short-term benefits of other arthroscopic procedures; namely, the ability to perform the procedure on an outpatient basis, less patient morbidity, and a faster return to sedentary work.
We sought to evaluate the outcomes of arthroscopically treated SGNC using validated outcome measures and to directly compare the outcomes of patients having SGNC decompression with labral repairs with outcomes of patients having SGNC decompression alone. We hypothesized that patients with ganglion cysts who were treated arthroscopically would have return to near normal function of their shoulders and that the outcomes for patients with ganglion cysts and associated superior labral anterior posterior (SLAP) tears would be no different than the outcomes for patients treated for ganglion cysts without associated labral tears.
MATERIALS AND METHODS
We retrospectively evaluated 18 consecutive patients who were treated arthroscopically for SGNC between 1999 and 2002 by one of two fellowship-trained shoulder surgeons. Of the 18 patients in our study, nine had an isolated arthroscopic decompression of a SGNC while the other nine had an arthroscopic decompression of a SGNC with a labral repair because of an associated SLAP tear. Our patient population included 17 male patients and one female patient, with the average age being 33 years (range, 17-49 years). The right shoulder was involved in 14 patients and the left shoulder was involved in four; the dominant extremity was involved in 12 patients. We included all patients with SGNC or patients with SGNC with associated SLAP tears. We excluded patients who had previous surgery on the affected shoulder, patients involved in workers' compensation claims, patients with litigation pending, or patients with less than 24-months followup. Applying these exclusion criteria, two patients were excluded from our study (Table 1). The average followup was 40 months (range, 24-58 months).
All patients were evaluated preoperatively by one of two attending orthopaedic shoulder surgeons (GRW, MLR) at our tertiary care referral center. All patients had a clinical examination, magnetic resonance imaging (MRI) (18/18), and electromyography (EMG) (18/18). Clinical examination included direct inspection of the shoulder musculature, strength testing of selected muscle groups, and range of motion (ROM) testing. Patients also were assessed using a validated shoulder questionnaire at the time of their initial evaluation. Patients often presented with posterior shoulder tenderness, external rotation weakness, and infraspinatus atrophy. On preoperative history, five of 18 (28%) patients had a history of trauma; the remaining 13 patients experienced insidious onset of pain without antecedent trauma. Several patients were involved in overhead sports including softball (n = 2), baseball (n = 1), tennis (n = 2), and volleyball (n = 3). We presumed the cyst was the source of pain after other sources (eg, impingement, rotator cuff tears, radiculopathy) were ruled out.
Magnetic resonance imaging was used to provide essential information regarding potential causes of suprascapular nerve compression. In addition, electrodiagnostic studies were used to confirm the diagnosis and localize the site of pathologic changes. Preoperatively, six of 18 (33%) patients had a positive EMG. This included three patients in the SGNC group without labral repair and three patients in the SGNC group with labral repair. All patients with positive EMGs had muscle atrophy noted on physical examination in the supraspinatus and/or infraspinatus fossa, whereas none of the patients with negative EMG findings had muscle atrophy. On MRI, the average ganglion cyst measured 2.4 cm × 1.8 cm (range, 1-5.9 cm) (Fig 1). The indication for operative intervention was severe pain and/or loss of function unresponsive to activity modification, nonsteroidal antiinflammatory medication, and physical therapy. Patients with positive EMG findings and associated atrophy were encouraged to have decompression to maximize the potential for neurologic recovery.
Arthroscopic decompression was considered for each patient after diagnostic evaluation. Magnetic resonance images were reviewed before surgery to define the extent and location of the ganglion cysts relative to known anatomic structures (ie, biceps tendon, glenoid labrum, scapular spine).
Patients were positioned in the beach chair position with their heads supported in horseshoe headrests and their shoulders off the side of the operating room table. The arthroscope was introduced through a posterior portal, and an anterosuperior portal was established from within the joint. Diagnostic arthroscopy of the glenohumeral joint was done to identify any concomitant intraarticular disorders. Particular attention was paid to the area of the glenoid and posterior capsule adjacent to the ganglion cyst. The arthroscope then was moved to the anterosuperior portal and an accessory posterolateral arthroscopy portal established to allow an approach more parallel to the posterior glenoid neck. This portal was located approximately 1 to 2 cm inferior to the posterolateral corner of the acromion, thereby allowing a more parallel approach to the glenoid neck.
If a labral tear was identified in the region of the ganglion cyst, a rosette knife was introduced through the defect, and the capsule was dissected subperiosteally from the glenoid neck. A probe then was introduced through this defect toward the spinoglenoid notch until the cyst was decompressed through the defect into the joint. Manual pressure on the skin over the ganglion cyst assisted in cyst evacuation. Finally, the labrum was repaired to the glenoid neck using bioabsorbable suture anchors.10
If an area of labral detachment was not apparent, a capsulotomy was performed near the junction of the capsule and the labrum and the glenoid neck were bluntly dissected at this level. In these cases, capsulotomy obviated the need for repair provided the defect was 1 cm or smaller.
Approximately 4 weeks postoperatively, a self-directed home exercise program of physical therapy was prescribed to obtain full glenohumeral motion and to strengthen the rotator cuff muscles, the deltoid, and the periscapular musculature. Special attention was directed toward establishing proper posture with scapular retraction exercises and strengthening of the trapezius, the rhomboids, and the serratus musculature.
The ASES6,14 and the Penn8 shoulder scores, both validated outcomes measures, were used to evaluate patients initially and at their latest followup. Subjective data included pain, function, and overall satisfaction; objective data involved physician assessment of active ROM on physical examination.
Pain levels were determined by patients using a visual analog scale ranging from 0 to 10 points, with 10 denoting disabling pain. Patients were asked to assign four different pain scores for pain present on that day, pain with the arm at rest by the side, pain with normal activities (eating, dressing, and bathing), and pain with strenuous activities (lifting, pushing and/or pulling, and throwing). The final pain score was an average of the four scores.
Patients rated their function by answering a questionnaire assessing their abilities to perform activities of daily living with the involved shoulder.6,8,14 The questionnaire was administered to the patients by an orthopaedic surgery fellow. The questionnaires assessed patients' abilities to use a back pocket, put on a coat, wash their opposite underarms, eat with a utensil, comb hair, use their arm at shoulder level, carry 10 pounds with the arm to the side, dress, pull, use their hands overhead, throw, do usual work, and participate in sports. The scale ranged from 0 to 3 points, with a score of 0 denoting complete inability to perform the task in question and 3 representing the ability to perform it without difficulty. The functional capacity for each patient was calculated by totaling the individual numeric responses and dividing it by the maximum score allowed for a percentage.
Patient satisfaction scores were determined by patients using a visual analog scale ranging from 0 to 10 points, in increasing order of satisfaction.
Active forward flexion and external rotation in adduction were assessed in the standing position using a goniometer. Range of motion was recorded in degrees for forward elevation and external rotation; internal rotation was recorded as the highest posterior spinal vertebra reached by the thumb. Range of motion was recorded for bilateral upper extremities preoperatively and at the latest followup.
Statistical analysis was performed using the two-tailed Student's t test for numeric data. Statistical significance was set at p < 0.05.
As we hypothesized in our introduction, we found that patients treated arthroscopically for SGNC had improved (p = 0.02) ASES and Penn shoulder scores (Table 2). In addition, there was better (p = 0.01) overall satisfaction when comparing preoperative and postoperative Penn scores. The average Penn satisfaction score preoperatively was 4/10 (range, 0-7), whereas the average Penn satisfaction score postoperatively was 9.3/10 (range, 8-10). All 16 patients were satisfied with their postoperative shoulder function.
We also found that patients treated arthroscopically for SGNC and labral tears had improved (p = ) ASES and Penn shoulder scores (Table 2). Although there was a difference in functional outcomes when comparing preoperative and postoperative ASES and Penn scores for the SGNC group (p = 0.03) and the SGNC/labral repair group (p = 0.02) (Tables 3, 4), there was no difference in outcomes when comparing the two groups (Tables 2, 4).
With additional evaluation, we found there was a difference in pain scores when comparing preoperative and postoperative ASES and Penn scores for the SGNC group (p = 0.01) and the SGNC/labral repair group (p = 0.01) (Tables 5, 6). However, we found that the postoperative ASES and Penn pain scores for patients who had SGNC decompression and patients who had SGNC decompression with labral repair were no different (Table 6). In addition, all patients preoperatively and postoperatively had ROM in the affected shoulder recorded as compared with the contralateral shoulder. There was no difference in ROM from preoperative to the latest postoperative examination within the specific groups or between patient groups.
Finally, all 18 patients achieved healing without any complications.
We hoped to evaluate surgical outcomes of patients treated for SGNC arthroscopically; we also sought to determine whether outcomes were different if the ganglion cysts were associated with labral tears. For the purposes of our study, we used the Penn and ASES shoulder scores, which are both validated outcome measures.
In the past, studies have shown that suprascapular neuropathy caused by extrinsic compression from a ganglion cyst should be treated with surgical decompression of the cyst openly or arthroscopically. Although open decompression of a SGNC has been associated with good to excellent results in many patients,3,11,12,15-17 in 1996, the first report of arthroscopic decompression for SGNC was presented.4 Three patients with suprascapular neuropathy secondary to a ganglion cyst were treated with arthroscopic decompression.4 All patients in this study had excellent outcomes and it was concluded that arthroscopic decompression of SGNC had the advantage of effectively treating associated intraarticular lesions and avoiding the morbidity of an open procedure. These intraarticular lesions are actually very common, as one MRI-based study showed that 89% of patients with a SGNC had an associated posterosuperior labral tear.18 Other studies have confirmed a high incidence of labral tears with arthroscopy being done before the open decompression of the spinoglenoid cyst.9 In our study, 50% of patients who presented with SGNC also had arthroscopically proven associated SLAP tears. Therefore, given that MRI and arthroscopy have shown a high association of SGNC with posterosuperior labral tears, treatment of a potential labral tear and decompression of the SGNC arthroscopically is recommended.
This study has the largest consecutive series of patients with SGNC who were treated arthroscopically, followed up for at least 2 years, and assessed using validated outcome measures. Although arthroscopic decompression of the cyst is technically challenging, results of our study indicate that it is an effective method for treatment of a SGNC, and may provide more rapid recovery because the deltoid and rotator cuff are not substantially violated. In addition, all patients treated for SGNC arthroscopically (regardless of the need for a labral repair) had improvement in their Penn and ASES scores.
The limitations of this study are as follows: (1) this was a retrospective review; (2) no patients had followup imaging studies to assess for ganglion cyst recurrence despite clinical improvement; (3) none of the with patients with positive EMGs had followup EMGs done to assess whether their preoperative neuropathies had been reversed; (4) and the arthroscopic surgeries all were done by fellowship-trained shoulder surgeons with advanced arthroscopic training (much more experienced in arthroscopy than the average orthopaedist). However, despite these limitations, results of our study show that arthroscopic treatment of SGNC is effective.
Most patients with SGNC will have pain on presentation and some will present with external rotation weakness. Magnetic resonance imaging confirms the diagnosis and defines the margins of the cyst; an associated postero-superior labral tear often is found. Nerve involvement can be identified and the site of neuropathy localized by EMGNCV. The goal of the treatment is to resolve the patient's symptoms, which can be accomplished arthroscopically by decompression of the cyst and repair of the labral tear when present. Our data suggest that in the hands of an appropriately trained arthroscopist, arthroscopic decompression of a SGNC (with labral repair when indicated) can lead to resolution of the patient's symptoms and complete functional recovery.
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