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Intraneural Ganglion of the Suprascapular Nerve: Case Report
Intraneural Ganglion of the Suprascapular Nerve: Case Report James Sanger, MD, Wilberto Cortes, MD, Ji-Geng Yan, MD From the Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI.
We present a case of multicystic ganglion of the suprascapular nerve in an 18-year-old man. Pain and shoulder weakness were present and examination showed weakness and atrophy of the supraspinatus and infraspinatus muscles. Electromyography showed severe denervation of the infraspinatus and supraspinatus muscles. At surgery a multicystic lesion of the suprascapular nerve extending approximately 5.7 cm from its origin was resected and reconstructed by sural nerve grafting. (J Hand Surg 2006;31A:40 – 44. Copyright © 2006 by the American Society for Surgery of the Hand.) Type of study/level of evidence: Therapeutic, Level V. Key words: Intraneural ganglion, suprascapular nerve, nerve-sheath ganglion.
ntraneural ganglion is an unusual benign tumor that rarely affects the upper extremity.1 Those involving the brachial plexus are even more uncommon with only 2 cases reported affecting this site, neither of which involved the suprascapular nerve.2,3 The current report discusses a mononeuropathy of the suprascapular nerve caused by intraneural ganglion.
I
Case Report An 18-year-old right-hand dominant man was seen for evaluation of left shoulder pain and weakness of 7 months’ duration. He is an active rugby player and began having pain in the shoulder at the end of rugby season. He attributed the pain to repetitive daily drills with a blocking sled. In this exercise he pushed repetitively against the sled with the shoulders up against a padded buttress and his head between them while other players pushed from behind. Although he did not remember a specific injury, he reported a poorly defined burning pain around the left shoulder that radiated into the shoulder and upper back. With the onset of pain there was an intermittent decrease in upper-arm strength. He had no similar weakness distal to the shoulder and no complaints of paresthesias or sensory loss. He had a history of rotator cuff tear as a result of a rugby injury 2 years before the onset of symptoms that resolved after physical therapy. Physical examination of all muscles was performed. There were no sensory deficits in the upper arm, specifically in the axillary and musculocutane40
The Journal of Hand Surgery
ous nerve distribution. The posterior deltoid grade was 4 of 5 and the middle and anterior deltoid grades were 5 of 5. The supraspinatus and external rotators were extremely weak. The external rotator grade was 2 of 5. Other muscles of the arm were graded 5 of 5 in strength. On examination there was a positive Tinel’s sign when deep pressure was applied to the junction of the trapezius and supraspinatus that radiated into the upper scapula area. Magnetic resonance imaging (MRI) sagittal and axial T1 and T2 sequences of the cervical spine showed a well-defined oval mass extending proximally and distally through the suprascapular notch. This lesion was hyperintense on T2-weighted images and iso-intense on T1-weighted images. There were no muscular edema, atrophy, or fatty changes around the subscapularis, infraspinatus, supraspinatus, and teres minor. The acromioclavicular joint and posterior shoulder joint were normal with no evidence of capsular tear, labral tear, or intra-articular abnormalities. No communication was detected between the acromioclavicular joint or glenohumeral joint and the suprascapular nerve. The biceps tendon was normal. The cervical cord appeared normal with minimal central protrusion of the C4 –C5 disc without compression of the cord or nerve foramina. Nerve conduction of the left median motor and sensory division, left ulnar motor and sensory division, left superficial radial sensory, and dorsal ulnar cutaneous showed no focal abnormalities. Severe abnormalities were detected, however, on needle
Sanger, Cortes, and Yan / Intraneural Ganglion
Figure 1. Intraoperative appearance of the suprascapular nerve with proximal fusiform enlargement (arrow).
electromyography. The infraspinatus had 3⫹ to 4⫹ positive waves of up to 1.2 mV with no clear motor units recruited. The supraspinatus had 3⫹ positive waves of up to 0.8 mV with motor unit recruitment severely decreased and some motor units with fast response. The following muscles were tested and found to have no abnormalities: upper and middle trapezius, rhomboids, deltoid, biceps brachii, pronator teres, flexor carpi radialis, triceps brachii, flexor carpi ulnaris, and the lower and middle cervical paraspinal muscles. These findings showed a suprascapular nerve lesion with denervation of the infraspinatus and supraspinatus. This ultimately led to a surgical consultation for definitive treatment. The patient was taken for surgical exploration with a preoperative diagnosis of severe mononeuropathy of the left suprascapular nerve. A standard incision for brachial plexus exposure parallel to the clavicle and sternocleidomastoid muscle was performed. The skin and subcutaneous tissues were dissected and the platysma was transected. The omohyoid was divided and the upper nerve roots of C5 and C6 were identified. On inspection these had moderate fibrosis arising from the anterior scalene fascia and muscle extending onto the suprascapular nerve. The fibrosis was dissected from the origin of the suprascapular nerve. Approximately 1.5 cm after its origin from the C5 and C6 formation of the upper trunk the suprascapular nerve was thickened and enlarged with a cystic component (Fig. 1). The nerve was followed distally and a separate incision was made for better exposure on the posterior aspect of the shoulder overlying the trapezius. Through this incision the distal portion of the suprascapular nerve was visualized, showing further cystic enlargement. The suprascapular notch was explored and decompressed. At this point intraoperative-evoked potentials were recorded proximal and distal to the lesion showing an
41
absence of response in both infraspinatus and supraspinatus muscles to different currents and intensities. Because we could not identify any intact nerve fibers under magnification and there was no effective intraoperative nerve conduction by either conduction studies or electromyography, we resected a 5.7-cm segment of the suprascapular nerve. The nerve was reconstructed with a reversed sural nerve graft. The specimen was sent for pathologic analysis. The final report confirmed the diagnosis of intraneural ganglion cyst. Microscopically a compressed lumen was apparent without an epithelial lining. The cyst wall was composed of connective tissue undergoing myxoid degeneration. Areas of fibroblastic proliferation were present. Residual intact nerve tissue was scant and showed swelling of the myelin sheath and edema. Scattered chronic inflammatory cells composed of macrophages and lymphocytes were present within the residual nerve fibers and the cyst wall. Areas of Schwann cell proliferation also were observed. These findings are characteristic of a nerve sheath cyst (Fig. 2). The morphology seen was consistent with a chronic compressed lesion. Chronic nerve damage from the nerve sheath cysts was manifest as replacement of the cyst wall by fibrous tissue. Interstitial inflammation within nerve fibers, Schwann cell proliferation, and swelling of the myelin sheath were
Figure 2. Histologic cross-section shows the cyst (arrow) surrounded by unmyelinated nerve fibers. Notice a compressed lumen without an epithelial lining. The cyst wall is composed of connective tissue undergoing myxoid degeneration. There are areas of fibroblastic proliferation and scant residual intact nerve tissue with swelling of the myelin sheath and edema. There are scattered chronic inflammatory cells composed of macrophages and lymphocytes within the residual nerve fibers and the cyst wall and areas of Schwann cell proliferation. The overall morphology is consistent with a chronic compressed lesion. Hematoxylin-eosin, ⫻20.
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The Journal of Hand Surgery / Vol. 31A No. 1 January 2006
Figure 3. Total number of upper-extremity intraneural ganglion cases in the literature since 1895 and distributions of nerve. Notice the predominance of ulnar nerve involvement. , Median; d, ulnar; , radial; , superficial radial; o, posterior interosseous; , digital; p, brachial plexus.
seen as further evidence of the chronicity of the lesion. The patient was seen 10 months after surgery. He had notable improvement in his shoulder motion with complete resolution of the pain. He also was working out on a regular basis and had notably increased shoulder strength. On physical examination the supraspinatus clearly had more bulk. There is still a considerable depression in the infraspinatus area and persistent atrophy when the hands are placed on the hips and he is asked to move the shoulder forward. The shoulder strength in external rotation is better, with a grade of 3 of 5.
Discussion Intraneural ganglion cyst is a rare benign nerve sheath tumor.4 This tumor predominantly occurs in the lower extremity, with almost all cases involving the common peroneal nerve and its branches.5 It usually affects middle-aged men and presents with symptoms of compression neuropathy. Because this cystic lesion first was described by Zum-Bush according to Chick et al4 in 1895 and subsequently was confirmed histologically by Hartwell6 in 1901, only 33 upper-extremity cases have been reported in the literature (Fig. 3). The most common upper-extremity nerve involved is the ulnar nerve7–13 but other sites have been described including the median nerve,14 radial nerve,1 superficial radial nerve,15 pos-
terior interosseous nerve,16 digital nerve,1 and brachial plexus.2,3 There are many facts that make this case unusual. First, the age of presentation usually is between 30 and 50 years. More than 90% of affected patients are middle-aged adults.1– 4 Only 1 previously published case involved an intraneural ganglion cyst of the median nerve in an 18-year-old man.6 Second, the clinical presentation is atypical, with the presenting symptom being burning shoulder pain in a poorly defined nerve distribution, followed by muscle atrophy. Third, the multicystic nature of the mass on histologic examination was unexpected because most lesions of this nature are single cysts.1 Fourth, the MRI findings did not correlate with the intraoperative findings. The classic signs of muscle denervation including muscle edema, muscle atrophy, and fatty changes within and around the muscle were completely absent.17,18 This is in contrast to both the physical examination and the intraoperative findings of complete nerve block by electromyography, proximal fibrosis, and almost entire involvement of the nerve distal from its origin. All these data suggest that the multicystic ganglion might be a more aggressive type of tumor. Further studies are required to ascertain if there is a difference in behavior between single and multicystic ganglions. The suprascapular nerve is known to be susceptible to compression because of its relatively fixed anatomic position under the transverse scapular ligament and the spinoglenoid ligament and because of its relation to the rotator cuff muscles.19 These anatomic structures make this nerve vulnerable to compression even by small space-occupying lesions. Although the clinical presentation can be explained by the involvement of the nerve fascicles as a result of either extrinsic or intrinsic compression, the etiology of this intraneural ganglion continues to be an area of intense debate. The intraneural theory describes the cause as mucoid degeneration of fibrous tissue after repetitive microtrauma.14 The extraneural theory suggests that a ganglion originates from a joint adjacent to the nerve and invades its substance, compressing the nerve as it displaces the fascicles.13 There is conclusive literature that intraneural ganglions can arise from a joint and enter the nerve through an articular branch of the nerve. Spinner et al20 showed that intraneural ganglions of the peroneal nerve are in direct continuity with the superior tibiofibular joint capsule via connection to the articular branch of the nerve. We can extrapolate this theory to our patient based on the suprascapular nerve articular branches that innervate the acromioclavicular joint capsule and the posterior shoulder joint capsule and the proximity of this nerve to the joints already
Sanger, Cortes, and Yan / Intraneural Ganglion
mentioned. The suprascapular arises from the upper trunk of the brachial plexus. At approximately 4.5 cm proximal to the transverse scapular ligament it gives a superior articular branch that runs alongside the main stem to enter the transverse scapular ligament and continues laterally, giving off a small branch to the posterior aspect of the acromioclavicular joint capsule.21 At the level of the scapula spine a large inferior articular branch runs obliquely to terminate in the posterior shoulder joint capsule.21 Although a connection between the ganglion and the acromioclavicular joint or the posterior shoulder joint was not apparent during surgery or by MRI it still is possible that the articular connection might be normal externally,23 small in appearance,22 and not always obvious.22,23 Communication between the intraneural ganglion and the adjacent joint has been identified in the median nerve14 and in the ulnar nerve.9 In addition the proximity of the main stem nerve to the joints provides further support to the latter theory. The nerve lies 2.9 cm from the supraglenoid tubercle to the motor branches of the supraspinatus muscle and 2.1 cm from the posterior glenoid rim to the infraspinatus motor branches.24 In our patient repetitive trauma within a confined space was a likely etiologic factor. The patient described performing repetitive drills, however, that subjected both sides of the neck and shoulder to repetitive blows, yet only the left side was involved. He had a history of rotator cuff injury and could have had a small ganglion that entered the nerve over the articular branch. No ganglion was evident originating from the shoulder joint or the acromioclavicular joint on MRI and during surgery no apparent connection between the ganglion and the joint was found. The latter might have been obscured by the presence of prominent scar tissue in our case, making any connection imperceptible. One important physical finding that might confuse the clinician is the presence of Tinel’s sign, given the fact that the suprascapular nerve is a motor nerve. The suprascapular nerve contains both afferent and efferent components.25 As already mentioned there are 2 major articular branches that are causes of neurogenic pain and prone to compression. In addition the suprascapular nerve receives cutaneous sensory fibers from the upper lateral arm in 15% of patients.26 This cutaneous nerve also communicates with a branch of the supraclavicular nerve.26 These 2 nerve pathways might explain the presence of Tinel’s sign in this case. The diagnosis was made with clinical evaluation, electromyography, and MRI. With MRI this lesion showed a hyperintense signal on T2-weighted images and a low-intensity signal on T1-weighted images.1,2 Although ultrasonography of the brachial plexus has
43
been shown to provide useful information regarding the lesion site and the extent and anatomic relationship to blood vessels, we believe that MRI is more useful because of its high soft-tissue contrast.27 With better equipment ultrasonography is becoming a useful adjunct for the diagnosis of brachial plexus tumors.28 Surgery is the treatment of choice to preserve or restore nerve function, with expected recovery within months.1 In most cases the lesion can be removed or decompressed without compromising nerve function.1 For those lesions that seem to arise from a joint and enter the nerve through the articular branch of the nerve the cyst does not have to be resected but just drained, and a search for the intra-articular connection should be performed to prevent recurrence. Although some investigators do not recommended performing a nerve graft even if the lesion appears to be extensive,4 we believe that this was the best option for potential recovery of function and resolution of pain in this particular case. Our decision to excise the tumor was based not only on the physical examination, preoperative nerve conduction test, and electromyogram but also on the intraoperative findings of extensive proximal fibrosis, unidentifiable nerve fascicles, and intraoperative conduction block. All these findings suggested a complete loss of function requiring excision and reconstruction with a reverse sural nerve graft. This case shows that the natural history of intraneural ganglion cyst can be more aggressive than previously thought and a treatment plan for each case needs to be individualized based on surgical exploration, intraoperative conduction tests, and surgeon experience. The postoperative functional recovery after surgical intervention as it pertains to this unique suprascapular neuropathy currently is unknown. It is well established that most patients with suprascapular neuropathy will have immediate pain relief but minimal resolution of muscle atrophy.19 In our patient infraspinatus wasting was more obvious than supraspinatus partially because supraspinatus atrophy may be hidden by the trapezius muscle. Although at follow-up examination the patient was working out on a regular basis and had notably increased shoulder strength, this does not confirm necessarily a return of supraspinatus function. With relief of pain the supraspinatus compensation can be achieved by an increase in the posterior deltoid and teres minor muscle function. Nevertheless complete resolution of pain has been achieved and further functional recovery is expected. Intraneural ganglion cyst should be considered in the differential diagnosis of any suprascapular nerve neuropathy regardless of the patient’s age. If documented we recommend early surgical exploration
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and excision or drainage to avoid complete loss of nerve function. Also a search for an articular connection is imperative to prevent recurrence. In the worstcase scenario in which there are no identifiable fascicles and the nerve gap is too extensive after resection, a nerve graft should be considered. The authors wish to thank Beth Kaczmarek, editorial consultant for the Department of Plastic Surgery, Medical College of Wisconsin, for her assistance in the preparation and revision of this article. Received for publication March 30, 2005; accepted in revised form August 24, 2005. 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. Corresponding author: James Sanger, MD, Department of Plastic Surgery, Medical College of Wisconsin, 8700 Watertown Plank Rd, Milwaukee, WI 53226-3595; e-mail: [email protected]. Copyright © 2006 by the American Society for Surgery of the Hand 0363-5023/06/31A01-0008$32.00/0 doi:10.1016/j.jhsa.2005.08.010
References 1. Giele H, Le Viet D. Intraneural mucoid cysts of the upper limb. J Hand Surg 1991;22B:805– 809. 2. Arnold PM, Oldershaw JB, McDonald LW, Langer BG. Myxomatous cyst of the brachial plexus. Case report. J Neurosurg 1990;73:782–784. 3. Nakamichi K, Tachibana S. Intraneural ganglion of the brachial plexus. J Hand Surg 1998;23B:123–125. 4. Chick G, Alnot J-Y, Silbermann-Hoffman O. Intraneural mucoid pseudocysts. A report of ten cases. J Bone Joint Surg 2001;83B:1020 –1022. 5. Nucci F, Artico M, Santoro A, Bardella L, Delfini R, Bosco S, Palma L. Intraneural synovial cyst of the peroneal nerve: report of two cases and review of the literature. Neurosurgery 1990;26:339 –344. 6. Hartwell AS. Cystic tumor of median nerve; operation: restoration of function. Boston Med Surg J 1901;144:582– 583. 7. Bowers WH, Doppelt SH. Compression of the deep branch of the ulnar nerve by an intraneural cyst. Case report. J Bone Joint Surg 1979;61A:612– 613. 8. Inhofe PD, Moneim MS. Compression of the ulnar nerve at the elbow by an intraneural cyst: a case report. J Hand Surg 1996;21A:1094 –1096. 9. Uetani M, Hashmi R, Hayashi K, Nagatani Y, Narabayashi Y, Imamura K. Peripheral nerve intraneural ganglion cyst: MR findings in three cases [musculoskeletal imaging]. J Comput Assist Tomogr 1998;22:629 – 632. 10. Jenkins SA. Solitary tumours of peripheral nerve trunks. J Bone Joint Surg 1952;34B:401– 411. 11. Gurdjian ES, Larsen RD, Lindner DW. Intraneural cyst of
12. 13. 14.
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the peroneal and ulnar nerves. Report of two cases. J Neurosurg 1976;23:76 –78. Zielinski CJ. Intraneural ganglion of the ulnar nerve at the wrist. Orthopedics 2003;26:429 – 430. Allieu PY, Cenac PE. Peripheral nerve mucoid degeneration of the upper extremity. J Hand Surg 1989;14A:189 –194. Jaradeh S, Sanger JR, Maas EF. Isolated sensory impairment of the thumb due to an intraneural ganglion cyst in the median nerve. J Hand Surg 1995;20B:475– 478. Gillies RM, Burrows C. Nerve sheath ganglion of the superficial radial nerve. J Hand Surg 1991;16B:94 –95. Hashizume H, Nishida K, Nanba Y, Inoue H, Konishiike T. Intraneural ganglion of the posterior interosseous nerve with lateral elbow pain. J Hand Surg 1995;20B:649 – 651. Saifuddin A. Imaging tumours of the brachial plexus. Skeletal Radiol 2003;32:375–387. Ludig T, Walter F, Chapuis D, Molé D, Roland J, Blum A. MR imaging evaluation of suprascapular nerve entrapment. Eur Radiol 2001;11:2161–2169. Safran MR. Nerve injury about the shoulder in athletes, part 1: suprascapular nerve and axillary nerve. Am J Sports Med 2004;32:803– 819. Spinner RJ, Atkinson JL, Tiel RL. Peroneal intraneural ganglia: the importance of the articular branch. A unifying theory. J Neurosurg 2003;99:330 –343. Aszmann OC, Dellon AL, Birely BT, McFarland EG. Innervation of the human shoulder joint and its implications for surgery. Clin Orthop 1996;330:202–207. Spinner RJ, Atkinson JL, Scheithauer BW, Rock MG, Birch R, Kim TA, et al. Peroneal intraneural ganglia: the importance of the articular branch. Clinical series. J Neurosurg 2003;99:319 –329. Spinner RJ, Atkinson JL, Harper CM Jr, Wenger DE. Recurrent intraneural ganglion cyst of the tibial nerve. J Neurosurg 2000;92:334 –337. Warner JP, Krushell RJ, Masquelet A, Gerber C. Anatomy and relationships of the suprascapular nerve: anatomical constraints to mobilization of the supraspinatus and infraspinatus muscles in the management of massive rotator-cuff tears. J Bone Joint Surg 1992;74:36 – 45. Rose DL, Kelly CR. Shoulder pain. Suprascapular nerve block in shoulder pain. J Kans Med Soc 1969;70:135– 136. Ajmani ML. The cutaneous branch of the human suprascapular nerve. J Anat 1994;185:439 – 442. Graif M, Martinoli C, Rochkind S, Blank A, Trejo L, Weiss J, et al. Sonographic evaluation of brachial plexus pathology. Eur Radiol 2003;14:193–200. Rettenbacher T, Sögner P, Springer P, Fiegl M, Hussl H, zur Nedden D. Schwannoma of the brachial plexus: cross-sectional imaging diagnosis using CT, sonography, and MR imaging. Eur Radiol 2003;13:1872–1875.
We present a case of multicystic ganglion of the suprascapular nerve in an 18-year-old man. Pain and shoulder weakness were present and examination showed weakness and atrophy of the supraspinatus and infraspinatus muscles. Electromyography showed severe denervation of the infraspinatus and supraspinatus muscles. At surgery a multicystic lesion of the suprascapular nerve extending approximately 5.7 cm from its origin was resected and reconstructed by sural nerve grafting. (J Hand Surg 2006;31A:40 – 44. Copyright © 2006 by the American Society for Surgery of the Hand.) Type of study/level of evidence: Therapeutic, Level V. Key words: Intraneural ganglion, suprascapular nerve, nerve-sheath ganglion.
ntraneural ganglion is an unusual benign tumor that rarely affects the upper extremity.1 Those involving the brachial plexus are even more uncommon with only 2 cases reported affecting this site, neither of which involved the suprascapular nerve.2,3 The current report discusses a mononeuropathy of the suprascapular nerve caused by intraneural ganglion.
I
Case Report An 18-year-old right-hand dominant man was seen for evaluation of left shoulder pain and weakness of 7 months’ duration. He is an active rugby player and began having pain in the shoulder at the end of rugby season. He attributed the pain to repetitive daily drills with a blocking sled. In this exercise he pushed repetitively against the sled with the shoulders up against a padded buttress and his head between them while other players pushed from behind. Although he did not remember a specific injury, he reported a poorly defined burning pain around the left shoulder that radiated into the shoulder and upper back. With the onset of pain there was an intermittent decrease in upper-arm strength. He had no similar weakness distal to the shoulder and no complaints of paresthesias or sensory loss. He had a history of rotator cuff tear as a result of a rugby injury 2 years before the onset of symptoms that resolved after physical therapy. Physical examination of all muscles was performed. There were no sensory deficits in the upper arm, specifically in the axillary and musculocutane40
The Journal of Hand Surgery
ous nerve distribution. The posterior deltoid grade was 4 of 5 and the middle and anterior deltoid grades were 5 of 5. The supraspinatus and external rotators were extremely weak. The external rotator grade was 2 of 5. Other muscles of the arm were graded 5 of 5 in strength. On examination there was a positive Tinel’s sign when deep pressure was applied to the junction of the trapezius and supraspinatus that radiated into the upper scapula area. Magnetic resonance imaging (MRI) sagittal and axial T1 and T2 sequences of the cervical spine showed a well-defined oval mass extending proximally and distally through the suprascapular notch. This lesion was hyperintense on T2-weighted images and iso-intense on T1-weighted images. There were no muscular edema, atrophy, or fatty changes around the subscapularis, infraspinatus, supraspinatus, and teres minor. The acromioclavicular joint and posterior shoulder joint were normal with no evidence of capsular tear, labral tear, or intra-articular abnormalities. No communication was detected between the acromioclavicular joint or glenohumeral joint and the suprascapular nerve. The biceps tendon was normal. The cervical cord appeared normal with minimal central protrusion of the C4 –C5 disc without compression of the cord or nerve foramina. Nerve conduction of the left median motor and sensory division, left ulnar motor and sensory division, left superficial radial sensory, and dorsal ulnar cutaneous showed no focal abnormalities. Severe abnormalities were detected, however, on needle
Sanger, Cortes, and Yan / Intraneural Ganglion
Figure 1. Intraoperative appearance of the suprascapular nerve with proximal fusiform enlargement (arrow).
electromyography. The infraspinatus had 3⫹ to 4⫹ positive waves of up to 1.2 mV with no clear motor units recruited. The supraspinatus had 3⫹ positive waves of up to 0.8 mV with motor unit recruitment severely decreased and some motor units with fast response. The following muscles were tested and found to have no abnormalities: upper and middle trapezius, rhomboids, deltoid, biceps brachii, pronator teres, flexor carpi radialis, triceps brachii, flexor carpi ulnaris, and the lower and middle cervical paraspinal muscles. These findings showed a suprascapular nerve lesion with denervation of the infraspinatus and supraspinatus. This ultimately led to a surgical consultation for definitive treatment. The patient was taken for surgical exploration with a preoperative diagnosis of severe mononeuropathy of the left suprascapular nerve. A standard incision for brachial plexus exposure parallel to the clavicle and sternocleidomastoid muscle was performed. The skin and subcutaneous tissues were dissected and the platysma was transected. The omohyoid was divided and the upper nerve roots of C5 and C6 were identified. On inspection these had moderate fibrosis arising from the anterior scalene fascia and muscle extending onto the suprascapular nerve. The fibrosis was dissected from the origin of the suprascapular nerve. Approximately 1.5 cm after its origin from the C5 and C6 formation of the upper trunk the suprascapular nerve was thickened and enlarged with a cystic component (Fig. 1). The nerve was followed distally and a separate incision was made for better exposure on the posterior aspect of the shoulder overlying the trapezius. Through this incision the distal portion of the suprascapular nerve was visualized, showing further cystic enlargement. The suprascapular notch was explored and decompressed. At this point intraoperative-evoked potentials were recorded proximal and distal to the lesion showing an
41
absence of response in both infraspinatus and supraspinatus muscles to different currents and intensities. Because we could not identify any intact nerve fibers under magnification and there was no effective intraoperative nerve conduction by either conduction studies or electromyography, we resected a 5.7-cm segment of the suprascapular nerve. The nerve was reconstructed with a reversed sural nerve graft. The specimen was sent for pathologic analysis. The final report confirmed the diagnosis of intraneural ganglion cyst. Microscopically a compressed lumen was apparent without an epithelial lining. The cyst wall was composed of connective tissue undergoing myxoid degeneration. Areas of fibroblastic proliferation were present. Residual intact nerve tissue was scant and showed swelling of the myelin sheath and edema. Scattered chronic inflammatory cells composed of macrophages and lymphocytes were present within the residual nerve fibers and the cyst wall. Areas of Schwann cell proliferation also were observed. These findings are characteristic of a nerve sheath cyst (Fig. 2). The morphology seen was consistent with a chronic compressed lesion. Chronic nerve damage from the nerve sheath cysts was manifest as replacement of the cyst wall by fibrous tissue. Interstitial inflammation within nerve fibers, Schwann cell proliferation, and swelling of the myelin sheath were
Figure 2. Histologic cross-section shows the cyst (arrow) surrounded by unmyelinated nerve fibers. Notice a compressed lumen without an epithelial lining. The cyst wall is composed of connective tissue undergoing myxoid degeneration. There are areas of fibroblastic proliferation and scant residual intact nerve tissue with swelling of the myelin sheath and edema. There are scattered chronic inflammatory cells composed of macrophages and lymphocytes within the residual nerve fibers and the cyst wall and areas of Schwann cell proliferation. The overall morphology is consistent with a chronic compressed lesion. Hematoxylin-eosin, ⫻20.
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The Journal of Hand Surgery / Vol. 31A No. 1 January 2006
Figure 3. Total number of upper-extremity intraneural ganglion cases in the literature since 1895 and distributions of nerve. Notice the predominance of ulnar nerve involvement. , Median; d, ulnar; , radial; , superficial radial; o, posterior interosseous; , digital; p, brachial plexus.
seen as further evidence of the chronicity of the lesion. The patient was seen 10 months after surgery. He had notable improvement in his shoulder motion with complete resolution of the pain. He also was working out on a regular basis and had notably increased shoulder strength. On physical examination the supraspinatus clearly had more bulk. There is still a considerable depression in the infraspinatus area and persistent atrophy when the hands are placed on the hips and he is asked to move the shoulder forward. The shoulder strength in external rotation is better, with a grade of 3 of 5.
Discussion Intraneural ganglion cyst is a rare benign nerve sheath tumor.4 This tumor predominantly occurs in the lower extremity, with almost all cases involving the common peroneal nerve and its branches.5 It usually affects middle-aged men and presents with symptoms of compression neuropathy. Because this cystic lesion first was described by Zum-Bush according to Chick et al4 in 1895 and subsequently was confirmed histologically by Hartwell6 in 1901, only 33 upper-extremity cases have been reported in the literature (Fig. 3). The most common upper-extremity nerve involved is the ulnar nerve7–13 but other sites have been described including the median nerve,14 radial nerve,1 superficial radial nerve,15 pos-
terior interosseous nerve,16 digital nerve,1 and brachial plexus.2,3 There are many facts that make this case unusual. First, the age of presentation usually is between 30 and 50 years. More than 90% of affected patients are middle-aged adults.1– 4 Only 1 previously published case involved an intraneural ganglion cyst of the median nerve in an 18-year-old man.6 Second, the clinical presentation is atypical, with the presenting symptom being burning shoulder pain in a poorly defined nerve distribution, followed by muscle atrophy. Third, the multicystic nature of the mass on histologic examination was unexpected because most lesions of this nature are single cysts.1 Fourth, the MRI findings did not correlate with the intraoperative findings. The classic signs of muscle denervation including muscle edema, muscle atrophy, and fatty changes within and around the muscle were completely absent.17,18 This is in contrast to both the physical examination and the intraoperative findings of complete nerve block by electromyography, proximal fibrosis, and almost entire involvement of the nerve distal from its origin. All these data suggest that the multicystic ganglion might be a more aggressive type of tumor. Further studies are required to ascertain if there is a difference in behavior between single and multicystic ganglions. The suprascapular nerve is known to be susceptible to compression because of its relatively fixed anatomic position under the transverse scapular ligament and the spinoglenoid ligament and because of its relation to the rotator cuff muscles.19 These anatomic structures make this nerve vulnerable to compression even by small space-occupying lesions. Although the clinical presentation can be explained by the involvement of the nerve fascicles as a result of either extrinsic or intrinsic compression, the etiology of this intraneural ganglion continues to be an area of intense debate. The intraneural theory describes the cause as mucoid degeneration of fibrous tissue after repetitive microtrauma.14 The extraneural theory suggests that a ganglion originates from a joint adjacent to the nerve and invades its substance, compressing the nerve as it displaces the fascicles.13 There is conclusive literature that intraneural ganglions can arise from a joint and enter the nerve through an articular branch of the nerve. Spinner et al20 showed that intraneural ganglions of the peroneal nerve are in direct continuity with the superior tibiofibular joint capsule via connection to the articular branch of the nerve. We can extrapolate this theory to our patient based on the suprascapular nerve articular branches that innervate the acromioclavicular joint capsule and the posterior shoulder joint capsule and the proximity of this nerve to the joints already
Sanger, Cortes, and Yan / Intraneural Ganglion
mentioned. The suprascapular arises from the upper trunk of the brachial plexus. At approximately 4.5 cm proximal to the transverse scapular ligament it gives a superior articular branch that runs alongside the main stem to enter the transverse scapular ligament and continues laterally, giving off a small branch to the posterior aspect of the acromioclavicular joint capsule.21 At the level of the scapula spine a large inferior articular branch runs obliquely to terminate in the posterior shoulder joint capsule.21 Although a connection between the ganglion and the acromioclavicular joint or the posterior shoulder joint was not apparent during surgery or by MRI it still is possible that the articular connection might be normal externally,23 small in appearance,22 and not always obvious.22,23 Communication between the intraneural ganglion and the adjacent joint has been identified in the median nerve14 and in the ulnar nerve.9 In addition the proximity of the main stem nerve to the joints provides further support to the latter theory. The nerve lies 2.9 cm from the supraglenoid tubercle to the motor branches of the supraspinatus muscle and 2.1 cm from the posterior glenoid rim to the infraspinatus motor branches.24 In our patient repetitive trauma within a confined space was a likely etiologic factor. The patient described performing repetitive drills, however, that subjected both sides of the neck and shoulder to repetitive blows, yet only the left side was involved. He had a history of rotator cuff injury and could have had a small ganglion that entered the nerve over the articular branch. No ganglion was evident originating from the shoulder joint or the acromioclavicular joint on MRI and during surgery no apparent connection between the ganglion and the joint was found. The latter might have been obscured by the presence of prominent scar tissue in our case, making any connection imperceptible. One important physical finding that might confuse the clinician is the presence of Tinel’s sign, given the fact that the suprascapular nerve is a motor nerve. The suprascapular nerve contains both afferent and efferent components.25 As already mentioned there are 2 major articular branches that are causes of neurogenic pain and prone to compression. In addition the suprascapular nerve receives cutaneous sensory fibers from the upper lateral arm in 15% of patients.26 This cutaneous nerve also communicates with a branch of the supraclavicular nerve.26 These 2 nerve pathways might explain the presence of Tinel’s sign in this case. The diagnosis was made with clinical evaluation, electromyography, and MRI. With MRI this lesion showed a hyperintense signal on T2-weighted images and a low-intensity signal on T1-weighted images.1,2 Although ultrasonography of the brachial plexus has
43
been shown to provide useful information regarding the lesion site and the extent and anatomic relationship to blood vessels, we believe that MRI is more useful because of its high soft-tissue contrast.27 With better equipment ultrasonography is becoming a useful adjunct for the diagnosis of brachial plexus tumors.28 Surgery is the treatment of choice to preserve or restore nerve function, with expected recovery within months.1 In most cases the lesion can be removed or decompressed without compromising nerve function.1 For those lesions that seem to arise from a joint and enter the nerve through the articular branch of the nerve the cyst does not have to be resected but just drained, and a search for the intra-articular connection should be performed to prevent recurrence. Although some investigators do not recommended performing a nerve graft even if the lesion appears to be extensive,4 we believe that this was the best option for potential recovery of function and resolution of pain in this particular case. Our decision to excise the tumor was based not only on the physical examination, preoperative nerve conduction test, and electromyogram but also on the intraoperative findings of extensive proximal fibrosis, unidentifiable nerve fascicles, and intraoperative conduction block. All these findings suggested a complete loss of function requiring excision and reconstruction with a reverse sural nerve graft. This case shows that the natural history of intraneural ganglion cyst can be more aggressive than previously thought and a treatment plan for each case needs to be individualized based on surgical exploration, intraoperative conduction tests, and surgeon experience. The postoperative functional recovery after surgical intervention as it pertains to this unique suprascapular neuropathy currently is unknown. It is well established that most patients with suprascapular neuropathy will have immediate pain relief but minimal resolution of muscle atrophy.19 In our patient infraspinatus wasting was more obvious than supraspinatus partially because supraspinatus atrophy may be hidden by the trapezius muscle. Although at follow-up examination the patient was working out on a regular basis and had notably increased shoulder strength, this does not confirm necessarily a return of supraspinatus function. With relief of pain the supraspinatus compensation can be achieved by an increase in the posterior deltoid and teres minor muscle function. Nevertheless complete resolution of pain has been achieved and further functional recovery is expected. Intraneural ganglion cyst should be considered in the differential diagnosis of any suprascapular nerve neuropathy regardless of the patient’s age. If documented we recommend early surgical exploration
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The Journal of Hand Surgery / Vol. 31A No. 1 January 2006
and excision or drainage to avoid complete loss of nerve function. Also a search for an articular connection is imperative to prevent recurrence. In the worstcase scenario in which there are no identifiable fascicles and the nerve gap is too extensive after resection, a nerve graft should be considered. The authors wish to thank Beth Kaczmarek, editorial consultant for the Department of Plastic Surgery, Medical College of Wisconsin, for her assistance in the preparation and revision of this article. Received for publication March 30, 2005; accepted in revised form August 24, 2005. 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. Corresponding author: James Sanger, MD, Department of Plastic Surgery, Medical College of Wisconsin, 8700 Watertown Plank Rd, Milwaukee, WI 53226-3595; e-mail: [email protected]. Copyright © 2006 by the American Society for Surgery of the Hand 0363-5023/06/31A01-0008$32.00/0 doi:10.1016/j.jhsa.2005.08.010
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