A twenty-one-year-old male, right-hand-dominant volleyball player developed pain in the anterior aspect of the right shoulder when spiking the ball. The pain had persisted for more than a year as of the time that the patient presented to our institution, but there was no history of trauma. Physical examination revealed tenderness on compression of the area over the coracoacromial ligament. The examination findings did not suggest shoulder instability, and the patient had no limitation of motion in the shoulder. There was no evidence of local heat, a mass, muscle weakness, or muscle atrophy. The O'Brien test, a provocative test for a superior labral anterior posterior (SLAP) lesion, was positive. The Neer impingement sign6 and the results of the active compression test7 were positive, but the Hawkins sign8 was negative. When the scapula was stabilized in the supine position, the right shoulder demonstrated glenohumeral inflexibility with a difference in horizontal flexion as compared with the result in the left shoulder. The patient had pain in the follow-through phase of the overhead motion. Radiographs of the shoulder demonstrated no abnormality. We therefore diagnosed impingement syndrome with muscle dysfunction and instructed the patient to perform stretching around the shoulder girdle; however, he returned because of shoulder pain within one month. MRI acquired at that time revealed a 12 mm × 12 mm × 6 mm (long axis/short axis/thickness) cystic mass under the coracoacromial ligament and no rotator cuff tear (Fig. 1). Ultrasonography acquired with the shoulder in the neutral position demonstrated a low-echoic mass (Fig. 2), which, when the shoulder was positioned in 90° of abduction and slight internal rotation, compressed the coracoacromial ligament from below. Aspiration of the cyst was performed under ultrasonographic guidance, yielding a clear yellow fluid with a jelly-like consistency. We suspected the cyst to be a ganglion, but the location of the stalk was unclear. The shoulder pain was relieved immediately after the aspiration procedure, and the patient was able to return to playing volleyball without pain. However, after several weeks, the pain recurred and aspiration of the ganglion became necessary eight times in the course of a year. Corticosteroid medication was also injected into the cyst on two of those occasions. Arthroscopic resection of the cyst was recommended. For this purpose, it was necessary to determine the precise location of the ganglion stalk in order to resect it completely so that the ganglion would not recur. MRI and ultrasonography proved ineffective for this purpose; we therefore performed three-dimensional CT. Under ultrasonographic guidance, we pierced the ganglion cyst with a needle, aspirated the content, and then injected the same volume of iodinated contrast material into the cyst, enabling us to perform three-dimensional CT. This allowed accurate visualization of the stalk of the ganglion cyst. The cyst was located between the coracoacromial ligament and the supraspinatus, and leakage of contrast medium into the subacromial bursa was evident. The ganglion stalk therefore arose from the subacromial bursa (Figs. 3-A and 3-B), and arthroscopic subacromial bursectomy was planned. An examination performed while the patient was under anesthesia revealed a full range of glenohumeral motion with no evidence of occult anterior or posterior instability. Arthroscopic examination revealed no evident articular lesion, no rotator cuff tear, no acromioclavicular joint lesion, and slight convexity of the bursa surface on the cuff side. Although the stalk of the ganglion was not clearly visualized, preoperative cystographic three-dimensional CT was helpful in determining the bursectomy area. We performed cuff-side and acromial-side bursectomy from the subcoracoacromial ligament area to the subacromial area with the use of a shaver and radiofrequency probe, and we preserved the coracoacromial ligament. The patient was managed with rest and immobilization of the shoulder in a sling for one week. Passive range-of-motion exercise was begun on the first day after the operation, and, at one week postoperatively, general active motion was allowed. At six weeks postoperatively, general sports activity was allowed after confirming that the shoulder girdle muscles were strong, and, at ten weeks postoperatively, the patient was able to make a complete return to volleyball without shoulder pain. There was no recurrence of the impingement, and ultrasonography showed no ganglion cyst at one year after surgery. The patient was able to play volleyball at the same level as that before the development of shoulder pain.
Oblique sagittal fat-suppressed T2-weighted magnetic resonance image of right shoulder, demonstrating a monolocular cyst below the coracoacromial ligament.
Ultrasonogram showing hypoechoic cystic lesion below the coracoacromial ligament (arrowhead). The letter "A" denotes the acromion, and the letter "C" indicates the coracoid process.
Figs. 3-A and 3-B Cystographic three-dimensional CT views showing a ganglion cyst (asterisk) located between the coracoacromial ligament and the supraspinatus as well as leakage of contrast medium (arrowhead) into subacromial bursa.
Chronic shoulder pain is common among athletes who use frequent overhead arm movements1-3,9,10, and, in young athletes, scapular dyskinesis or other muscle dysfunction is common. When these patients are examined for the first time, muscle dysfunction of the shoulder girdle should be investigated, and, when dysfunction is found, it must be treated with physical therapy3. Occasionally, impingement syndrome may be the result of a rotator cuff tear, shoulder instability, or a superior labral anterior posterior (SLAP) lesion10. In refractory cases, when physical examination has not been useful in determining the cause of the pain, MRI is employed. Generally, cystic masses about the shoulder are uncommon11-15. Recently, however, there have been a number of reports of ganglia compressing the suprascapular nerve and causing chronic shoulder pain5,16. Cysts located near the labrum, on the spinoglenoid notch, are referred to as paralabral or labral cysts5,15,16. Some authors have suggested that there may be a causal relationship between glenoid labral cysts and glenoid labral tears12,17,18. However, in the case of our patient, the cyst was not located near the labrum; rather, it was below the coracoacromial ligament and arose from the subacromial bursa. Ganglion cysts in this area are extremely rare. Chiou et al. reported that fifteen of 3000 patients with chronic shoulder pain had ganglion cysts demonstrable with ultrasound. The cysts were located below the coracoacromial ligament in five patients13. There have been no previous reports of impingement syndrome due to ganglion cysts located below the coracoacromial ligament in athletes who use overhead arm movements. With use of dynamic ultrasonographic examination, Wu et al. demonstrated that, during throwing simulation in such athletes, displacement of the coracoacromial ligament in the painful shoulder was significantly greater than that of the asymptomatic shoulder19. In the case of our patient, ultrasonography showed that the ganglion compressed the coracoacromial ligament when the shoulder was in 90° of abduction and in internal rotation, and that the symptom improved immediately after ultrasound-guided aspiration of the cyst, leading us to postulate that the impingement syndrome was caused by the ganglion cyst.
MRI or ultrasound is effective for detection of cystic lesions. However, these imaging modalities make it difficult to gain a three-dimensional appreciation of the lesions. Several reports have indicated that cystography is a good method for investigating the accurate location of a ganglion12,20. Therefore, to obtain a more accurate and clearer image, we performed cystographic three-dimensional CT after puncture of the cyst under ultrasonographic guidance. To our knowledge, the previous use of this method has not been reported. While arthroscopic decompression or open resection has been the treatment of choice for glenoid labral cysts, several recent reports have indicated the advantage of arthroscopic resection of these cysts over the traditional open procedure5,21. Although our patient did not have a glenoid labral cyst, arthroscopic bursectomy was effective because we had visualized the location of the ganglion cyst accurately. We therefore believe that precise localization of the lesion is essential in patients presenting with cysts in uncommon locations.
Confirmation of the location of the ganglion stalk during the arthroscopic surgery is essential to prevent local recurrence. However, the placement of instruments during arthroscopic surgery may rupture the ganglion cyst before its location can be confirmed. Therefore, accurate preoperative localization of the stalk is necessary with the help of diagnostic imaging. Cystographic three-dimensional CT is very useful in the precise localization of a ganglion cyst when the cyst is in an unusual location, as was the case with our patient, and it is also helpful in the planning of surgical management. Moreover, the procedure can be performed with minimal invasiveness with use of ultrasound. Following this protocol, our patient was relieved of shoulder pain immediately after the operation and returned to playing volleyball at the same level as before the onset of shoulder pain.