n sports medicine update Suprascapular Vascular Anomalies as a Cause of Suprascapular Nerve Compression Carlton Houtz, MD; Patrick C. McCulloch, MD ticle describes one such com- atrophic changes were seen on Abstract: The vascular anatomy at the spinoglenoid and su- pressive etiology and reviews inspection of the periscapular prascapular notches appears to be more variable than previ- the literature on vascular muscles. Magnetic resonance ously thought. In patients presenting with signs of suprascap- anomalies at the suprascapu- arthography demonstrated ular nerve compression, vascular causes must be considered. lar and spinoglenoid notches. edema and moderate atrophy Especially when considering percutaneous or arthroscopic within the supraspinatus and treatment, awareness of these entities may help to guide treat- CASE REPORT infraspinatus muscles consis- ment decisions, aid in identification of the anatomy, and pre- A 52-year-old man who tent with acute-on-chronic de- vent unwanted vascular insult. had undergone 2 previous nervation, but no evidence of a failed shoulder surgeries for tear. No lesion was identified presumed rotator cuff tear pre- within the suprascapular notch he first report of compres- or bone tumors, cysts second- sented with pain and progres- (Figure 1). Tsion of the suprascapular ary to capsulolabral pathol- sive weakness of forward ele- A second electromyogram nerve was by Schilf in 1952.1 ogy, and fractures. Several vation, abduction, and external and nerve conduction study Since then, the understanding authors have described su- rotation of his left shoulder. obtained 12 weeks after the of this neuropathy and its pos- prascapular nerve palsy in No rotator cuff tear was seen first studies showed dysfunc- sible etiologies has improved patients with a massive rota- during the previous surgeries, tion of the suprascapular substantially. Those thought tor cuff tear associated with and a subacromial decompres- nerve at or proximal to the to be at highest risk include fatty infiltration or muscle at- sion with acromioplasty was suprascapular notch, with the athletes engaging in repetitive rophy.7-10 At times, anatomic performed. Although he ini- supraspinatus and infraspina- overhead activity, especially variants of the neurovascular tially reported being unable to tus demonstrating evidence tennis and volleyball play- structures may lead to com- play basketball and participate of both acute and ongoing ers.2-6 Nerve compression has pression of the suprascapular in weight lifting, his symp- denervation and chronic been attributed to a stenotic nerve; however, this has been toms progressed to limiting his changes. The decision was notch, an ossified transverse sparsely described in previous ability to work. made to proceed with supra- scapular ligament, soft tissue literature.8,11 The current ar- Electromyography and scapular nerve decompression nerve conduction studies dem- at the suprascapular notch. onstrated mild denervation in With the patient in the The authors are from the Highland Clinic (CH). Shreveport, Louisiana; and the Methodist Center for Sports Medicine (PCM), The Methodist the infraspinatus and supraspi- beach-chair position, a thor- Hospital, Houston, Texas. natus muscles. Physical thera- ough diagnostic arthroscopy The authors have no relevant financial relationships to disclose. py failed to improve his weak- was performed. Evidence Correspondence should be addressed to: Carlton Houtz, MD, Highland ness or discomfort, which existed of a previous ac- Clinic, 1455 E Bert Kouns Industrial Loop, Ste 210, Shreveport, LA 71105 ([email protected]). he localized to the posterior romioplasty and some scar- doi: 10.3928/01477447-20121217-07 scapular region, and some ring of bursal tissues, but no 42 ORTHOPEDICS | Healio.com/Orthopedics n sports medicine update evidence existed of a rota- tor cuff tear. A lateral view- ing portal was established in the subacromial space. The coracoacromial ligament was identified and followed down to the base of the coracoid. A straight medial Nevasier portal was made under direct vision with a spinal needle, similar to the technique de- scribed by Lafosse et al.12 Just medial to the conoid 1A 1B ligament, the transverse scap- Figure 1: Sagittal magnetic resonance imaging anatomy sequence showing mild decreased muscle bulk and early fatty ular ligament was identified, change of the supra- and infraspinatus consistent with acute-on-chronic changes (A). Fat-suppressed, fluid-sensitive and both the suprascapular ar- sequence showing significant interstitial edema of muscles consistent with acute denervation changes (B). tery and nerve were identified passing beneath the ligament. throscopic cautery device and DISCUSSION ligament is approximately Two smaller branches of the then divided. The artery then The suprascapular nerve 1.3 cm posterior to the poste- suprascapular artery originat- lifted superiorly off the nerve, has contributions from C4- rior aspect of the clavicle, 2.9 ing proximal to the ligament leaving the nerve freely mo- C6 via the upper trunk of the cm medial to the acromiocla- were traveling with the main bile in the notch (Figure 4). brachial plexus. It is a mixed vicular joint, and 4 cm deep to trunk of the suprascapular Six months postopera- nerve with sensory branches the skin surface.13 The nerve artery under the ligament. tively, the patient had no to the acromioclavicular joint, then courses approximately These 3 arterial vessels were pain, full range of motion, coracoacromial ligament, and 3 cm medial to the supragle- compressing the nerve within and 5/5 rotator cuff strength. glenohumeral joint capsule noid tubercle and 1.8 cm me- the notch (Figure 2). Electromyography demon- and has 2 motor branches that dial from the posterior glenoid A narrow arthroscopic bit- strated significant interval innervate the supraspinatus rim at the base of the scapular er was then used to divide and improvement with no signs muscle. The nerve descends spine.14 The distance from the resect the transverse scapular of active denervation, normal through the posterior triangle palpable posterolateral corner ligament. However, the artery recruitment, and a full 100% of the neck before passing of the acromion to the base of was still tethered medially by interference pattern. At 1-year beneath the superior trans- the scapular spine is approxi- the smallest of the branch- follow-up, the patient re- verse scapular ligament in mately 4.5 cm.15 It then trav- es (Figure 3). This branch mained symptom free and had the suprascapular notch. The els beneath the inferior trans- was cauterized using an ar- returned to manual labor. superior transverse scapular verse scapular ligament in 2 3 4 Figure 2: Arthroscopic image of the suprascapular Figure 3: Arthroscopic image after release of the Figure 4: Arthroscopic image of ligation of the artery passing under the transverse scapular ligament. ligament showing the pulsatile artery in the notch, smallest branch allowing the artery to lift superi- tethered by a small medial branch. orly out of the notch, exposing the nerve. JANUARY 2013 | Volume 36 • Number 1 43 n sports medicine update the spinoglenoid notch before superior transverse scapular notch to avoid placing the ar- in nerve compression.23 The innervating the infraspinatus ligament, after which it typi- tery at risk.11 patient underwent an open muscle via 2 or more motor cally gives off branches that Recently, Yang et al22 dis- vessel ligation and resection branches.14,15 supply the supraspinatus mus- sected 103 cadaveric shoulders with good clinical improve- Suprascapular nerve inju- cle. The artery then continues and found a single suprascapu- ment. They noted that the ad- ries are common in repetitive distally, traveling beneath the lar artery that passed under dition of intravenous contrast overhead athletes, such as ten- inferior transverse scapular the superior transverse supra- when performing magnetic nis, volleyball, and throwing ligament before forming an scapular ligament in 26.2% of resonance imaging may help athletes, for 2 main reasons. anastamosis with the scapular the shoulder specimens. They to differentiate this from the First, this nerve is vulnerable circumflex artery and descend- noted that the venous anatomy more common ganglion cyst.23 to stretch injuries because it ing branch of the transverse was more variable, with 21.3% The vascular anatomy at takes a circuitous course and cervical artery.18 having multiple veins, and all the spinoglenoid and supra- can become tethered in several The most common ana- of the vessels passing superior scapular notches appears to be places, such as the suprascapu- tomic arrangement at the su- to the ligament only 59.4% of more variable than previously lar and spinoglenoid notches. prascapular notch is that the the time. The same vascular thought. In patients presenting Second, those sports are often artery travels superior to the arrangement described in the with signs of suprascapular associated with labral pathol- transverse scapular ligament current case (with the supra- nerve compression, vascular ogy, which can lead to nerve while the nerve travels under scapular vein crossing over the causes must be considered. compression from paralabral it. This spawned the classic transverse scapular ligament Especially when considering cysts. The resultant loss of rota- teaching pneumonic that when and the artery running under) percutaneous or arthroscopic tor cuff strength can cause de- faced with an obstacle, “the occurred