Texas Equine Veterinary Association

www.teva-online.org • Page 9 suprascapular nerve Injury ("shoulder sweeny") Suprascapular nerve damage is usually the result of direct trauma to the point of the shoulder where the nerve courses around the scapula neck. The suprascapular nerve innervates the infraspinatus and supraspinatus muscles that lie on each side of the scapular spine. The infraspinatus muscle is responsible for a majority of the shoulder joint lateral support (acts as a collateral ligament). Following loss of innervation to the infraspinatus muscle, there is typically pronounced lateral instability/shoulder slip during weight bearing. Lameness is variable and can be severe (grade 3/5 to 5/5) at the time of initial injury. "Shoulder slip" is usually not present immediately following injury, but becomes more apparent three to seven days after injury. Unfortunately, it is impossible to determine the degree of nerve injury based on clinical signs and lameness; there is currently no diagnostic method to determine if nerve regeneration will occur. Diagnosis can be confirmed with an electromyography; however, this is only useful seven days following injury. Shoulder radiographs should be obtained to insure no other pathology is present. Both conservative and surgical management for treatment of suprascapular nerve injury have been advocated. 9,10 Conservative management consists of stall rest and has yielded a good return to function. In the few available case studies, average time for complete shoulder stability to return is seven months. In addition to stall rest, non-steroidal, anti-inflammatory medications, topical cold therapy/hydrotherapy, vitamin E, and intravenous DMSO can be used as adjunct treatment options. 9 Surgical management consisting of suprascapular nerve decompression has also been advocated as a treatment option. It has been suggested that surgical suprascapular nerve decompression can expedite return of lateral stability, decrease muscle atrophy, and accelerate the return to function in comparison to conservative management. 10 The potential benefits of surgical therapy should be weighed against potential risks associated with surgery. Reported risks following surgery are supraglenoid tubercle fracture or scapular neck fracture. Many times suprascapular nerve injuries are treated conservatively; however, if little to no improvement is noted after three to four months, surgical suprascapular nerve decompression is recommended. Accupuncture may be of some value as an alternative therapy. Of the few reports evaluating the long-term success following damage to the suprascapular nerve, prognosis for return to soundness with both conservative and surgical management is good. Even following return to functional soundness, complete resolution of supraspinatus and infraspinatus muscle atrophy may not completely resolve. Bicipital tendonitis/Bursitis Primary lameness attributable to bicipital bursa inflammation or biceps brachii tendonitis is uncommon (Figure 8). 11 Lameness is typically associated with cranial shoulder trauma or a penetrating wound resulting in septic bursitis; bicipital bursitis can present as a septic or non-septic condition. The biceps brachii tendon originates on the supraglenoid tubercle, passes over the cranial aspect humeral intertubercular groove (which contains a bursa), and inserts along the medial aspect of the radius. Lameness originating from the biceps brachii tendon or bicipital bursa often yields a painful response when the tendon is pulled laterally. Definitive diagnosis of biceps brachii tendon or bicipital bursa lameness should be confirmed with bicipital bursa intrasynovial anesthesia. The biceps brachii tendon should be evaluated by ultrasound to confirm the presence of tendon damage and/or an increased amount of bicipital bursa fluid. Additionally, skyline radiographs of the intertubercular groove radiographs should be obtained. 12 Treatment is highly dependent on the pathology present. Conservative management consisting of rest and rehabilitation (controlled exercise) is preferred in cases of biceps brachii Figure 7. Craniocaudal (left) and mediolateral (right) radiographs approximately four months following closed reduction of the above (Figure 6) shoulder luxation. The horse still has some lateral instability; however, at this time there are minimal signs of secondary osteoarthritis post reduction. (Photo courtesy of Dr. Ashlee Watts, Texas A&M University)

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