Shoulder injuries are found in 21% of the adult population. In athletes, especially those who play overhead sports such as baseball, volleyball or tennis, shoulder injuries are much more prevalent. Most of the time these injuries are simply chronic inflammatory issues such as rotator cuff tendonitis or impingement. In these instances your health care provider, athletic trainer, physical therapist or physician may prescribe a non-specific rehabilitation program, which usually works. However if the diagnosis is wrong, rehabilitation may fail.
A differential diagnosis to chronic shoulder inflammation is Suprascapular Nerve Palsy. Suprascapular nerve palsy is a condition in which the suprascapular nerve – sits above the shoulder blade – is entrapped and nerve supply to the supraspinatus muscle and potentially the infraspinatus muscle is cut off. The suprasacpular nerve arises out of the C5/C6 nerve roots and passes through the suprascapular notch under the suprascapular ligament, which lie under the upper trapezius muscle. After it passes through this notch the nerve bifurcates with one branch innervating the supraspinatus muscle and the other branch innervating the infraspinatus muscle.
In some instances, the nerve will get entrapped and cause palsy and subsequent muscle wasting in the one or both of these rotator cuff muscles. The most common cause is nerve compression caused by ganglion cyst in the notch. Athletes, particularly overhead, such as baseball, volleyball, tennis, players are at risk for developing the palsy secondary to rotator cuff tears, repetitive microtrauma, or scarring of the muscle, which in turn entraps the nerve, thus causing palsy.
If palsy occurs there will be weakness for external rotation and Glenohumeral abduction. Pain may or may not be present. The athlete may experience additional shoulder issues such as, tendonitis, subacromial impingement or tears secondary to decreased rotator cuff stability which may cause pain and mask the true injury. Upon evaluation there will likely be visible wasting in the supraspinous or infraspinous fossa when compared bilaterally. If nerve palsy is suspected a surgeon will order an EMG to test nerve velocity and transmission.
Rehabilitation involves focused activation exercises for the rotator cuff muscles, beginning with isometric exercises with progression to single plane, full range of motion strengthening with final progression to multiplanar strengthening. Avoid exacerbating activity such as throwing and overhead movements. If the issue does not resolve decompression surgery will be required.
Like many shoulder pathologies, Suprascapular Nerve Palsy can be prevented. Repetitive motion can precipitate poor joint mechanics and poor muscle activation patterns. A focused program designed to correct muscle imbalances, obtain proper Glenohumeral arthrokinematics and acquire optimal neuromuscular force coupling will help prevent the palsy.
If you have shoulder pain which is not subsiding with traditional therapy, seek a second opinion to find out what else could be going on.