a tear of the rotator cuff or cervical disc disease. Treatment ... recovery after surgery. Koppel and ..... two had a fair recovery with a difference of between 20 and.
Entrapment of the suprascapular nerve Th. Fabre, C. Piton, G. Leclouerec, F. Gervais-Delion, A. Durandeau From the Groupe Hospitalier Pellegrin, Bordeaux, France
perative release for entrapment of the suprascapular nerve was carried out in 35 patients. They were assessed at an average of 30 months (12 to 98) after operation using the functional shoulder score devised by Constant and Murley. The average age at the time of surgery was 40 years (17 to 67). Entrapment was due to injury in ten patients and no cause was found in three; 34 had diffuse posterolateral shoulder pain. The strength of abduction was reduced in all the patients. The average Constant score, unadjusted for age or gender, before operative release was 47% (28 to 53). In 25 of the patients both the supraspinatus and infraspinatus muscles were atrophied and seven had isolated atrophy of the infraspinatus muscle. The average conduction time from Erb’s point to the supraspinatus muscle and to the infraspinatus muscle was 5.7 ms (2.8 to 12.8) and 7.4 ms (3.4 to 13.4), respectively. In two patients MRI revealed a ganglion in the infraspinatus fossa and, in another, a complete rupture of the rotator cuff. The average time from the onset of symptoms to operation was ten months (3 to 36). A posterior approach was advocated. The average Constant score, after operative release, unadjusted for age or gender was 77% (35 to 91). The overall result was excellent in ten of the patients, very good in seven, good in 14, fair in two, and poor in two. The symptomatic and functional outcome in our series confirmed the usefulness and safety of operative decompression for entrapment of the suprascapular nerve.
O
J Bone Joint Surg [Br] 1999;81-B:414-9. Received 14 May 1998; Accepted after revision 31 October 1998
Th. Fabre, MD, Orthopaedic Surgeon C. Piton, MD, Chief Clinical Assistant G. Leclouerec, MD, Chief Clinical Assistant F. Gervais-Delion, MD, Chief Clinical Assistant A. Durandeau, MD, Professor of Orthopaedic Surgery Groupe Hospitalier Pellegrin, Place Amélie-Raba Léon, 33076 Bordeaux Cedex, France. Correspondence should be sent to Dr Th. Fabre. ©1999 British Editorial Society of Bone and Joint Surgery 0301-620X/99/39113 $2.00 414
Entrapment of the suprascapular nerve may cause pain in the shoulder which may be attributed wrongly to tendinitis, a tear of the rotator cuff or cervical disc disease. Treatment is often delayed until there is atrophy of the supraspinatus, infraspinatus, or both. Such delay impedes functional recovery after surgery. 1 Koppel and Thompson described compression of the nerve in the suprascapular notch, and others have reported 2-6 this. The mechanisms of entrapment, the clinical picture and diagnosis have all been thoroughly described else4,7,8 9 where. Rengachary et al, Mestdagh, Drizenko and 10 11 12 Ghestem, Bigliani et al and Warner et al have undertaken anatomical studies which have helped to clarify the 13 pathogenesis of the condition. Various sporting activities, particularly those involving repetitive movements of the 14,15 arm, have been identified as causes of the syndrome. Enlargement of the suprascapular nerve may be associated with a tear of the rotator cuff and may indeed be caused by 12 it. 16 Ganzhorn et al and Thompson, Schneider and Ken17 nedy reported cases of compression of the suprascapular nerve by a ganglion. Many publications on the subject have appeared in the literature as a result of the increasing use of 18-21 MRI. We present a series of 35 patients who had entrapment of the suprascapular nerve, treated by surgical release.
Patients and Methods Between 1985 and 1995, 41 patients were operated on by the senior author (AD) for entrapment of the suprascapular nerve. Five of these patients were lost to review and one has since died; 35 (85%) were included in this long-term postoperative assessment (Table I) in which 30 were examined by an independent assessor. The other five were both questioned by telephone and returned a detailed questionnaire. There were 26 men and 9 women, with a mean age at operation of 40 years (17 to 67). The right shoulder was involved in 19 patients, in 17 of whom it was the dominant side. Eighteen patients reported their occupational activity to be very demanding on their shoulders. Four had overexerted their affected shoulder in sports, one at volleyball, two while swimming and one in throwing the javelin. Three of the 35 patients had idiopathic entrapment THE JOURNAL OF BONE AND JOINT SURGERY
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Table I. Details of the 35 patients with entrapment of the suprascapular nerve before surgery. The Constant score was not adjusted for age or gender
Case
Gender
Age (yr)
Professional activity
Aetiology
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
M F M M M M M M M F F M F F M F M F M M M M F F M M M M M M M M M M M
33 22 59 27 42 30 26 52 63 67 48 38 66 40 21 26 17 59 34 29 36 36 57 43 63 24 55 28 50 17 24 54 26 51 48
Agriculturist Student Retired Assistant director Turner Driver Manufacturer Mason Doctor Retired Violinist Driver Retired Maid Workman Maid Student Housewife Carpenter Agriculturist Qualified workman Office worker Retired Housewife Retired Military Retired Unemployed Carpenter Student Student Qualified workman Carpenter Qualified workman Baker
Overuse Overuse sport Overuse Overuse sport Overuse Overuse Overuse Overuse Overuse Overuse Overuse Overuse Overuse Overuse Overuse Overuse Overuse sport Overuse Overuse Overuse Overuse Overuse sport Unknown Unknown Unknown Trauma Trauma Trauma Trauma Trauma Trauma Trauma Trauma Trauma Trauma
volleyball swimmer
javelin
swimmer
Preoperative Constant Preoperative score delay (%) (mth)
Postoperative Constant score Affected side/ opposite side (%)
Follow-up (mth)
43 48 39 46 * 49 53 49 45 46 47 49 * * * 48 51 47 53 51 51 49 * 42 * 48 * * * 51 51 43 49 28 49
77 75 74 89 75 88 84 75 71 66 56 79 60 83 80 80 82 70 70 88 92 92 84 71 74 91 78 91 75 91 95 50 84 35 85
18 18 18 22 60 20 18 18 19 49 42 20 82 72 72 35 37 25 18 33 19 20 96 24 98 19 96 72 84 47 18 18 24 32 18
7 5 36 6 36 3 13 3 8 6 36 12 12 8 5 7 10 10 12 8 3 8 6 4 5 5 7 3 6 5 4 23 3 9 24
93 87 83 93 87 91 91 90 82 83 81 91 80 89 93 89 97 87 91 95 95 95 85 85 83 94 90 95 87 91 95 87 87 83 91
* patients operated on before 1991 were not evaluated using the Constant score
of the suprascapular nerve for which no obvious cause was established. Direct injury to the shoulder had occurred in ten patients. In this group, four (cases 24, 30, 32 and 34) presented with incomplete palsy of the upper trunk of the brachial plexus (C5-C6). In one patient this was associated with fracture of the neck of the humerus (case 32) and in another (case 34) with a tear of the rotator cuff; both had been operated on before referral. The four patients with palsy of the brachial plexus had almost fully recovered before the operation, since only the deficit of the suprascapular nerve persisted at that time. One (case 33) of the ten patients who had suffered direct trauma had a fracture of the scapula, and another (case 26) a fracture of the clavicle. Neither osseous nor nerve lesions were localised in four of the patients who had suffered direct trauma to the shoulder. Function was assessed by the rating system of Constant 22 and Murley (Table II) with 15 points for freedom from pain, 20 for a full range of function, 40 for active range of movement, and 25 for full strength. The mean Constant score before surgery (Table I) unadjusted for age or gender was 47 (28 to 53) from a maximum, normal score of 100 patients. VOL. 81-B, NO. 3, MAY 1999
All patients with the exception of one (case 7) suffered deep, diffuse posterolateral pain in the shoulder which, in some cases, radiated to the upper arm, the neck or the front of the chest (Table II). The mean preoperative score for pain was 8 points (1 to 14). All 35 patients reported tenderness on palpation over the suprascapular notch or over the spinoglenoid notch. Abduction averaged 80° (50 to 170), forward elevation 150° (50 to 170), external rotation at 0° of abduction 20° (0 to 45) and internal rotation to reach L1 ( 4 levels). The mean preoperative score for painfree movement was 26 (8 to 37). The measurement of strength was carried out as descri6 bed by Narakas with weights applied at the wrist with the forearm in pronation, the elbow extended and the arm abducted 90° in the plane of the scapula. The weight, up to 11 kg, must be maintained for five seconds, five times. The average abducting force before surgical treatment was 1.5 kg (0 to 3.5). Atrophy of the supraspinatus and infraspinatus muscles was classified subjectively as mild, barely discernible, moderate, easily discernible or severe with obvious flattening of the muscle mass in each fossa. A total of 25 patients
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TH. FABRE,
C. PITON,
G. LECLOUEREC,
Table II. Preoperative scores for 26 patients and postoperative scores for 22 35 patients for the rating scale of Constant and Murley. Values are given as the average (SD) Constant score
Preoperative
Postoperative
Absolute score (scale 0 to 100) Pain (scale 0 to 15) Function (scale 0 to 20) Painfree range of motion (scale 0 to 40) Strength (scale 0 to 25)
47 8 10 26 3
77 13 18 36 10
± ± ± ± ±
3.5 2.0 1.5 3.0 0.5
± ± ± ± ±
9.0 2.0 1.5 2.0 2.0
had atrophy of both muscles, moderate atrophy in seven and severe in 18. Seven patients had isolated atrophy of the infraspinatus muscle, mild in one and moderate in six. Both muscles appeared normal in three of the patients. The crossover adduction test, carried out by 21 of the patients, was positive in eight. The diagnosis was confirmed by electrophysiological studies in all 35 patients. The mean conduction time from Erb’s point to the supraspinatus muscle on the affected side was 5.7 ms (2.8 to 12.8) and to the infraspinatus muscle, 7.4 ms (3.4 to 13.4). All electrophysiological studies were carried out using a coaxial needle. In 20 patients signs of nerve degeneration were found, including a block in conduction and denervation changes, namely, increased insertional activity, positive sharp waves and fibrillation potentials. Isolated denervation of the infraspinatus muscle was seen in only four patients (cases 2, 3, 6, 31). MRI or CT arthrography was carried out in 11 patients. In two (cases 3 and 31), MRI showed a ganglion at the base of the spine of the scapula extending into the infraspinatus fossa, and in another (case 18) a complete rupture of the rotator cuff involving the supraspinatus muscle near its insertion. Non-operative treatment, including active exercise of the rotator cuff and the scapular stabilising muscles with massage, was always given for at least two months before a decision was made regarding surgery. The mean time from the onset of symptoms to operation was ten months (3 to 36). This was less than six months for 12 patients, between six and 18 months for 18, and over 18 months for five. The patients were operated on in a semiprone position with the arm draped free and the head turned away. The skin incision was made parallel and slightly proximal to the spine of the scapula. The trapezius was split in the axis of its fibres. The suprascapular muscle was retracted backwards with a layer of fatty tissue. The index finger was used to locate the suprascapular ligament, which was excised, with care being taken to avoid injuring the suprascapular artery and vein lying deep to it in the suprascapular notch. The suprascapular nerve was identified using electrical stimulation and decompressed focally. The trapezius muscle was repaired and the wound closed. Active movements within the limits of pain were allowed beginning on the first day after operation. The same posterior approach was extended to expose the spinoglenoid notch and infraspinatus fossa in two patients in
F. GERVAIS-DELION,
A. DURANDEAU
whom preoperative electrophysiological studies had shown isolated involvement of the infraspinatus (cases 2 and 6); both the suprascapular and spinoglenoid ligaments were excised. A ganglion arising from the posterior scapulohumeral joint caused entrapment of the suprascapular nerve in the spinoglenoid notch in two patients (cases 3 and 31) and in these, the deltoid and trapezius insertions were detached to facilitate removal of the cyst. In one patient (case 18) a complete rupture of the supraspinatus muscle near its insertion was repaired during the same operation.
Results A final examination was made at a mean follow-up of 38 months (18 to 98) after the operation, at which time the mean Constant score, unadjusted for age or gender (Table I), was 77% (35 to 95) with no difference according to the aetiology. There was an excellent result in ten of the patients in whom the difference in the Constant score between the affected and healthy shoulder was five or less. Seven had a very good result with a difference between the affected shoulder and healthy shoulder of between six and ten, 14 had a good result with a difference of between 11 and 20, two had a fair recovery with a difference of between 20 and 30 and two were poor with a difference in the Constant score of greater than 30. There were no intraoperative or early postoperative complications. A tear of the rotator cuff was diagnosed at follow-up in three patients, two of whom were reoperated on in our unit (cases 11 and 13); the other refused surgery (case 32). Influence of the operation on pain. On the subjective scale, 22 of the 34 patients who had pain before operation, had none at the final review (15 points). One still had slight pain (13 or 14 points) and eight had moderate pain (10 to 12 points). All eight of these patients reported that their pain was very much less than before the operation; four of them (cases 10, 11, 32, 34) reported pain during light activities (7 or 8 points). Influence of the operation on everyday activities. Among the 15 patients who overexerted their shoulder during the course of professional use, 14 were able to participate in all of their previous activities without restriction; one patient was obliged to change his job (case 5). One (case 24) in whom the cause of the lesion was unknown was able to return to her previous professional tasks. Of the ten patients who had an injury to the shoulder, seven recovered a normal level of function, one was placed on sick leave (case 34), and the remaining two were unable to resume their former job (cases 29, 32). Three of the four patients who practised sports recovered their previous level of proficiency. The javelin thrower, at the time of review at 37 months, was free from pain but had not yet attained his previous standard of performance. The other five patients, who were retired, recovered their previous level of everyday activity. THE JOURNAL OF BONE AND JOINT SURGERY
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Influence of the operation on range of motion. A painfree range of active movement was achieved by 25 patients, including flexion, abduction, external and internal rotation, all of which were symmetrical and normal; none had disorders of the contralateral shoulder. Active mobility was less than perfect in nine patients (mean score, 34 out of the 40 possible points) two of whom were operated on for a complete tear of the rotator cuff (cases 11 and 18), and another refused further treatment for the same lesion (case 13). There was a severe deficit of active movement in one patient (case 34), who had been operated on elsewhere for an injury to the rotator cuff one year before decompression of the suprascapular nerve (16 out of 40 points). Influence of the operation on strength. The mean force of abduction which was attained at follow-up was 5 kg (mean 0.5 to 10). For comparison, the mean abduction force in the contralateral unaffected shoulder was 7 kg (3 to 11). Influence of the preoperative delay. The mean improvement in the Constant score after surgery for patients operated on within six months was 36 (20 to 46). For comparison the mean improvement for patients operated on after six months was 23 (7 to 43). Influence of the operation on atrophy. Of the 25 patients who had atrophy of both muscles, 13 had full recovery of muscle bulk. In seven atrophy became less marked and in five there was no noticeable atrophy of the supraspinatus while that of infraspinatus became less marked. Isolated atrophy of infraspinatus, which was found in seven patients before surgery, persisted in four.
Discussion The anatomy of the suprascapular nerve has been well 11,12 described. Most cases of entrapment occur when it courses under the transverse scapular ligament. The nerve then runs obliquely across the supraspinatus fossa toward the rim of the glenoid fossa and enters the infraspinatus fossa around the base of the spine of the scapula coursing beneath the spinoglenoid ligament, 23,24 which is a much less common site of entrapment before giving off three to four branches to the infraspinatus muscle. The causes of entrapment in our series include direct injury, traction and repetitive activities which led to overuse of the upper limb. Several authors have reported tethering of the nerve as it passes through the notch 23,25,26 beneath the suprascapular ligament. Rengachary et 9 al attributed the clinical manifestations to kinking of the nerve beneath the transverse scapular ligament. Movement of the shoulder and the scapula puts traction on the suprascapular nerve, causing inflammation and constriction. For this reason we decided to include the four patients who had had incomplete injuries to the brachial plexus which had completely recovered except for the suprascapular branch. The abnormal kinematics of the VOL. 81-B, NO. 3, MAY 1999
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scapula, caused by temporary palsy of the brachial plexus, were probably responsible for the damage to the suprascapular nerve explaining the isolated persistence of this deficit. A ganglion in the spinoglenoid notch is another cause of 8,16,18,19,21,27 entrapment of the suprascapular nerve. More rarely, a ganglion extending into the supraspinatus fossa has also been reported to compress the nerve in the supra7,28 scapular notch. In the present series the patients who were operated on within six months of the onset of symptoms had better recovery than those who had the operation after more than six months. In the light of our experience, we recommend that electrophysiological studies and MRI should always be used when clinical findings suggest entrapment of the suprascapular nerve. The motor deficits are confirmed on the basis of decreased conduction velocities from Erb’s 2,17,25 The point to the supraspinatus, infraspinatus or both. test can also distinguish between entrapment in the suprascapular notch and the spinoglenoid notch. Differentiation between patients with tears of the rotator cuff and those 13 with lesions of the suprascapular nerve may be difficult. Moreover, the two syndromes can coincide as was the case in one of our patients. MRI will reveal damage to the rotator cuff. If such damage warrants repair, this should be carried out during the operative decompression of the suprascapular nerve. This was done in one of our patients with a good result. The four patients with poor recovery after operation probably had compression of the nerve in association with an undiagnosed rupture of the rotator cuff. They were managed surgically in three cases with a twostage procedure which compromised the final result; the other refused further operation. MRI will demonstrate or exclude the presence of a ganglion either in the spino17,20,29 glenoid notch, where it will cause isolated paralysis of the infraspinatus, or in the supraspinatus fossa compressing the branches to the supraspinatus muscle in the supra7,19,27 scapular notch. 9 There are many opinions concerning the indications and timing for operative decompression of the suprascapu5,6,13 lar nerve. Patients who have dysfunction of the nerve without muscular atrophy or evidence of a space-occupying lesion are usually prescribed non-operative treatment, 30 consisting of rest, followed by physiotherapy. After three to four months, if the symptoms persist, we advocate operative decompression of the nerve. If there is evidence of muscular atrophy or severe pain, not controlled by drugs, the operation should not be delayed beyond three months. In our series, the patients who were operated on within six months of the onset of symptoms, showed better recovery than those who had surgery after a longer inter8,16,17,27 val. Most authors agree that operative excision is indicated in patients whose symptoms result from compression of the nerve by a ganglion. If the patient experiences a decrease in pain or increase in strength, and the
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TH. FABRE,
C. PITON,
G. LECLOUEREC,
electrophysiological findings show improvement during the preoperative period, the operation should be postponed or cancelled. When this occurs, the patient will usually recover spontaneously, particularly if the entrapment fol5,25 lows trauma. Patients who have entrapment at the spinoglenoid notch not caused by a ganglion, often recover completely without 8,14,31 operation. In our series, two patients had entrapment by a ganglion in the spinoglenoid notch with pain, weakness and atrophy of the infraspinatus. One of these, a 24-year-old rugby football player (case 31), showed an improved Constant score of 95 after surgical excision of the ganglion and ligament. Despite slight persistence of the atrophy, he continued to play rugby. The other patient (case 3), aged 59 years, recovered muscle bulk and attained a Constant score of 74. He returned to his previous level of daily activity. There has been some discussion as to the surgical approach that should be used for decompression of suprascapular nerves. Some authors prefer an anterior approach 32,33 but over the medial aspect of the coracoid process, 2,5,6,25 4 most gain access posteriorly. Post and Mayer recommended a posterior approach with release of the insertion of trapezius from the spine of the scapula. We prefer to divide trapezius along the line of its fibres following the 2 5 recommendation of Clein and Callahan et al. This approach gives quick and ample access to the suprascapular notch. Simple excision of the transverse scapular ligament allows the nerve and fat pad to slip from the suprascapular notch and makes extensive neurolysis of the 3,25 nerve unnecessary. A nerve stimulator was used in some cases to distinguish the nerve from the surrounding fat. 26 Primary resection of the notch, as reported by Rask, is not used systematically by most authors. We enlarged the notch in two patients early in the series but later discontinued this practice because the nerve was observed to bulge from the notch after excision of the suprascapular ligament. The approach through the trapezius muscle can be enlarged to provide access to the spinoglenoid notch and infraspinatus fossa, if necessary. Since isolated compression of the fascicles of the infraspinatus nerve in the suprascapular notch could occur, we recommend excision of both the suprascapular and spinoglenoid ligaments during the same operation in patients who have an isolated lesion of the infraspinatus muscle which has been confirmed by electrophysiological studies. The use of a functional assessment score is helpful in the 22 management of disorders of the shoulder. We found the Constant scoring system to be simple, reliable, cheap and easy to use in a clinical setting. Assessments are made of both shoulders; the score can be adjusted for age and gender. The symptomatic and functional outcome in this series of 35 patients confirms the usefulness and safety of operative decompression for entrapment of the suprascapular nerve.
F. GERVAIS-DELION,
A. DURANDEAU
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
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30. Martin SD, Warren RF, Martin TL, et al. Suprascapular neuropathy: results of non-operative treatment. J Bone Joint Surg [Am] 1997;79-A: 1159-65. 31. Black KP, Lombardo JA. Suprascapular nerve injuries with isolated paralysis of the infraspinatus. Am J Sports Med 1990;18:225-8. 32. Murray JWG. A surgical approach for entrapment neuropathy of the suprascapular nerve. Orthop Rev 1974;3:33-5. 33. Shupeck M, Onofrio BM. An anterior approach for decompression of the suprascapular nerve. J Neurosurg 1990;73:53-6.
