Shoulder pain is a common reason for visits to primary care physicians, who are most likely to diagnose it as rotator cuff tendinitis1,2—often erroneously. The complexity of the joint and the overlapping pathologies that may present as shoulder pain highlight the need to take a closer look when dealing with this diagnostic challenge. Often, a targeted medical history—including the mechanism of injury and pain-provoking and pain-relieving factors—and a problem-based physical examination (incorporating many of the maneuvers highlighted in the text and tables that follow) will lead to an accurate diagnosis without the need for imaging studies. We recommend that imaging be reserved for patients who don’t respond to conventional treatments, cases in which the diagnosis is in doubt, and instances in which surgical intervention is being considered.
The 3 cases* that follow, and the take-away message incorporated in each, will give you an opportunity to test—and to hone—your shoulder pain diagnostic skill.
The history: Jesse, a 17-year-old student who’s active in football and track, came in during track season complaining of severe left shoulder pain. He denied any traumatic event or previous injury to the shoulder, but reported that any motion involving the shoulder caused pain. It hurt at night, the patient said, when he lay on his left side.
The physical: No muscle atrophy, redness, or swelling was evident, nor was there any indication of asymmetry or ecchymosis in the affected area. Jesse’s neck range of motion was normal; he had a very hard time with any active motion of the shoulder, however, because of the pain. Evaluation of scapular motion demonstrated scapular dyskinesis3,4 without winging. Passive motion of the glenohumeral joint was much better than active motion. Strength testing appeared to be grossly intact but was limited by the pain. Shoulder impingement testing was positive. Sensation and deep tendon reflexes were intact.
WHAT’S THE DIAGNOSIS?
Subacromial bursitis, suggested by the patient’s pain and altered scapular motion, was our working diagnosis, and we administered a subacromial injection of corticosteroid with lidocaine, for diagnostic as well as therapeutic purposes. Reexamination after the injection revealed immediate partial improvement in resting pain, range of motion, and strength. We referred Jesse to physical therapy with a focus on scapular stabilization and rotator cuff strength. Three months later, Jesse returned to our office, complaining of weakness in his left shoulder. The pain had subsided a week after his first appointment, so he’d never gone to physical therapy. The weakness, which he had first noticed about 2 months after starting a lifting program in preparation for football season, was limited to resistance exercises, especially overhead shoulder presses and bench press. There were no other changes in his history, and he reported no reinjuries. Physical examination revealed atrophy of the supraspinatus and infraspinatus muscles (FIGURE 1) and external rotation and shoulder abduction (in the scapular plane) resistance tests revealed weakness of these muscles. There was no scapular winging. The cervical spine exam was normal, and neurovascular status was intact in both upper extremities.
Severe shoulder pain, followed by weakness
Physical examination reveals atrophy of the patient’s supraspinatus (^) and infraspinatus (+) muscles.
New evidence points to nerve injury. Based on Jesse’s current history and physical, nerve injury was our new working diagnosis. (We considered the possibility of a rotator cuff tear, but this was not corroborated by the history). We ordered an electromyogram/nerve conduction velocity study to localize the lesion. The test revealed a brachial plexitis/neuritis (also known as Parsonage-Turner syndrome or brachial amyotrophy). The etiology of most atraumatic brachial plexopathies is unknown, and most are thought to be viral or autoimmune in nature.5,6
A classic case of Parsonage-Turner syndrome. The typical presentation of Parsonage-Turner syndrome (like Jesse’s) is one of acute, intense shoulder pain for no known reason. After 1 to 3 weeks, the pain resolves and the patient is left with weakness, usually of the supraspinatus and infraspinatus muscles. The weakness typically resolves with time, but full resolution may take 6 to 9 months.5,6 (In Jesse’s case, it took about 6 months.)
The take-away message: Look beyond the shoulder
As this case illustrates, not all shoulder pain originates in the shoulder. When evaluating shoulder pain, it is essential to consider other causes. The differential diagnosis for shoulder pain includes cervical spine disorders, cholecystitis (right shoulder), diaphragmatic irritation (eg, in the case of splenic rupture, usuallyinvolving the left shoulder), cardiac disease, and thoracic outlet syndrome.7 Evaluation of the cervical spine should be part of a complete shoulder examination. It is vital to follow a systematic approach that carefully assesses the cervical region for the possibility of nerve root impingement and radicular dysfunction masquerading as a primary shoulder disorder. (TABLE 18,9 details pain and sensory distribution patterns, reflex involvement, and potential motor impairments associated with various spinal nerve root levels.)
Assessing the cervical spine
Adapted from: Miller JD, et al. Am Fam Physician. 20008; Eubanks JD. Am Fam Physician.20109
Practitioners should develop their own approach to “clearing the neck.” A logical order is to note posture of the head/neck/shoulders, observe active motion, perform palpation and provocative tests, and then assess neurologic function with sensation/reflex/strength testing. Provocative tests that can help to identify cervical involvement relating to shoulder pain include Spurling’s maneuver, axial compression test, abduction relief sign, and Lhermitte’s sign.10,11
The history: Mark, a 17-year-old, right-handed volleyball player, presented with right shoulder pain, which he felt whenever he spiked or served the ball. The pain started last season, Mark said, diminished during the months when he wasn’t playing, then got progressively worse as his activity level increased. The pain was in the posterior aspect of the shoulder.
The physical: Physical examination revealed a well-developed, but thin (6’4”, 170 pounds) young man who was not in distress. The general examination was benign, and a joint-specific exam showed no asymmetry or atrophy on inspection and no tenderness to palpation over the posterior and anterior soft tissues of the right shoulder. Rotator cuff testing yielded intact strength for all 4 muscles, but external rotation and supraspinatus testing elicited pain. The crank test, drawer sign, load and shift test, relocation test, and sulcus sign, detailed in TABLE 2,12-14 were all positive for shoulder instability; the Clunk and O’Brien tests were negative, and the contralateral shoulder exam was within normal limits. General joint laxity was observed, with the ability to oppose the thumb to the volar forearm and hyperextension noted in both elbows and knees. There were no outward signs of connective tissue disease. Because of the chronicity of Mark’s pain and the progressive nature of his symptoms, we ordered radiographs, including anterior-posterior, lateral axillary, and scapular Y views. These films showed a nearly skeletally mature male without bony abnormalities; the humeral head was well located in the glenoid.
Testing for shoulder instability 12-14
*Perform only if apprehension test is positive.
ROM, range of motion
WHAT’S THE DIAGNOSIS?
Multidirectional instability with recurrent subluxations and probable acute rotator cuff tendinitis was our provisional diagnosis. Treatment focused on physical therapy, with a concentration on scapular stabilization and rotator cuff strengthening. Shoulder instability is relatively common and represents a spectrum of disorders ranging from dislocation to subluxation to simple laxity.12,13 A complete loss of humeral articulation within the glenoid fossa is evidence of dislocation, whereas subluxation includes approximation of the humeral head to the limits of the glenoid rim. Dislocation typically results from trauma, whereas subluxation can be the result of microtrauma and repetitive overuse injury. Anterior instability is the most common type and is reported in as many as 95% of all dislocations.13
The take-away message: Rule out instability
The shoulder is one of the most complex joints in the body. The rotator cuff structures, the glenoid labrum, and the collective capsular ligaments provide structural stability to the glenohumeral joint.12,13 The shoulder is vulnerable to instability because the shallow glenoid fossa offers little bony support for the humeral head. Thus, instability should always be included in an assessment of shoulder pain. Key factors to consider in identifying shoulder instability include the location of the pain, the direction of traumatic force applied, the presence of a known complete dislocation vs apprehension with specific movement, the position of the arm in which pain is elicited, a previous occurrence of instability (subluxation or dislocation), and the presence of tingling or numbness.12-14 The maneuvers detailed in TABLE 212-14 can help identify instability, as they did in this case. Patients with hypermobility are at increased risk for shoulder instability, so a targeted exam and patient history aimed at identifying signs and symptoms of hypermobility is needed, as well.
Ask the patient to attempt to: