Shoulder impingement syndrome refers to pain in the shoulder due to entrapment of the supraspinatus tendon and subacromial bursa between the greater tuberosity of the humerus and ventral-caudal corner of the acromion during forward flexion and internal rotation of the shoulder. Chronic impingement may lead to attritional degeneration of the rotator cuff (RC) tendon. Tendon injury typically progresses from edema to tendinosis and finally ending with a tear of the RC in chronic cases. In chronic cases, eventual degeneration and tear of the long head of the biceps tendon may also occur. These patients present with a painful shoulder with activity, especially in the overhead position. Unlike cervical pathology, the pain associated with RC tear may be referred along the deltoid muscle, rarely extends below the elbow, and is reported as radiating proximally (3). Additionally, patients with an RC tear often complain of pain at night when lying on an abducted shoulder along with weakness with overhead activities.

Physical examination maneuvers to differentiate this entity from C5 and C6 radiculopathy include the shoulder abduction test, as well as the Neer and Hawkins impingement tests (1,4). Shoulder abduction classically relieves nerve root tension and results in pain relief with radiculopathy but exacerbates pain in patients with shoulder pathology. However, this overhead position will relieve nerve root tension and diminish pain associated with radiculopathy. A Spurling’s sign is indicative of cervical rather than shoulder pathology and is elicited by neck extension and ipsilateral rotation reproducing radiating shoulder and arm pain. The Neer impingement test is performed by forward elevation overhead and internal rotation of the shoulder, which worsens RC impingement. The Hawkins impingement test is performed by forward elevation to 90 degrees and internal rotation of the shoulder, which exacerbates the
symptoms associated with supraspinatus tendon impingement. A diagnostic subacromial injection with lidocaine can also help to differentiate shoulder impingement from cervical pathology as well. RC tears from other causes, such as trauma, can be distinguished from cervical pathology in the same manner as above. Additionally, unlike cervical pathology, distal sensation and deep tendon reflexes should be unaffected with shoulder pathology.

Glenohumeral instability may present as a “dead arm” syndrome where the patient may describe ventral shoulder pain and vague arm numbness and weakness. They may also report a “feeling of slipping” out of the joint. Axillary nerve injury is common in this disorder and may present as deltoid weakness and atrophy. A positive apprehension test will differentiate this from a patient with a C5 radiculopathy.

Osteoarthritis of the shoulder can affect the glenohumeral, acromioclavicular (AC), sternoclavicular, and scapulothoracic joints and may result in vague shoulder pain. Etiologies may be idiopathic, posttraumatic, or inflammatory in nature. Patients present with a painful shoulder with weak abduction and external rotation. Additionally, patients present with stiffness and limited external rotation and forward elevation as the anterior capsule of the shoulder and subscapularis muscle from a contracture (1). Associated labral tears may form resulting in glenoid ganglion cysts that rarely impinge upon the suprascapular nerve. A positive shoulder impingement sign, magnetic resonance imaging (MRI) of the shoulder, and pain relief with glenohumeral injection with lidocaine are useful to differentiate shoulder pain and weakness caused by a glenoid cyst rather than cervical radiculopathy (5).

The physical examination must be correlated with advanced imaging studies. Asymptomatic patients have been reported to have abnormal findings in up to 25% of cervical MRI and up to 54% of shoulder MRI scans depending on the age of the patient (1).

Osteoarthritis of the AC joint results in ventral shoulder pain with forward flexion and adduction. A special Zanca anteroposterior radiograph with 10 degrees of cephalic tilt may be used to better visualize the AC joint. A diagnostic AC joint anesthetic injection can help differentiate osteoarthritis from C5 radiculopathy, along with intact deltoid strength and distal sensation.

Upper cervical radiculopathy (C2-C4) may also present with neck and/or shoulder and must be considered when evaluating the patient with chronic upper girdle pain. Patients typically describe a prolonged history of pain along the neck, upper back, and chest wall in the absence of any motor deficit. They may have a positive Spurling’s sign and shoulder abduction test, which would reproduce pain in the patient with an internal shoulder disorder.

Lateral and medial epicondylitis refer to tendonosis of the extensor carpi radialis brevis and wrist flexor-pronator tendon origins, respectively. Lateral epicondylitis, commonly called tennis elbow, results in lateral elbow pain with activity. On examination, resisted extension of the long finger (Maudsley’s test) exacerbates the symptoms. Tennis elbow may mimic radial tunnel syndrome or C5-C6 radiculopathy. Preserved distal sensation along with intact deltoid and biceps strength helps differentiate this entity from cervical radiculopathy. Medial epicondylitis (commonly called golfer’s elbow) results in medial elbow pain and may be associated with concomitant cubital tunnel syndrome, mimicking C8 radiculopathy. Painful resisted wrist pronation and tenderness over the medial humeral epicondyle, along with preserved distal sensation helps differentiate this entity from C8 radiculopathy. A diagnostic anesthetic injection at the respective humeral epicondyle can also help confirm the diagnosis.

DeQuervain’s disease refers to stenosing tenosynovitis around the first dorsal tendon compartment, affecting the abductor pollicis longus and extensor pollicis brevis. Symptoms include pain along the distal radial forearm and wrist. Finkelstein’s test is a provocative maneuver, where symptoms are reproduced with ulnar deviation of the wrist while placing the thumb in a fist. This entity can be differentiated from C6 radiculopathy because of preserved biceps strength and absence of radiating pain above the elbow.