Suprascapular Nerve related pain often plays a part in difficult to diagnose localized or ill defined shoulder pain. Difficult to diagnose pain or ill defined pain can be very frustrating for the patient and physician.
Suprascapular Nerve Injury Pain
A complex network of nerves from the neck and cervical spine (levels C4-T1) called the brachial plexus supplies sensation and power from the chest and shoulder girdle down to the fingers.
Why get a second opinion? Because the nerve origins are fixed at their origin from the spinal cord in the neck and the girdle is very mobile (only attached to the trunk by clavicle) and they are relatively superficial (not covered by lots of muscles), these nerves are particularly susceptible to injury from stretch and compression. Studies have shown that stretching a nerve by as little as 6% can lead to abnormalities in its ability to conduct a signal. The blood supply to a nerve can be compromised with a stretch of 8% and is totally occluded when stretched 15%. The same types of changes occur in nerve function with compression. Of course the amount of injury or damage to a nerve depends on the magnitude and duration of the insult, but it is easy to imagine that irreversible changes and damage can be done both with a large single event and chronic multiple small events or some combination of both.
Click here to watch a video about suprascapular nerve surgery.
Aside from injury, a relatively rare (2-3/100,000/year) and not entirely understood syndrome that most likely is the result of multiple underlying causes that can also result in severe pain and nerve dysfunction is called Neuralgic Amyotrophy (sometimes also called Parsonage-Turner Syndrome). Neuralgic Amytrophy is thought to most likely have an autoimmune component, meaning that the nerves may be under attack by the patient’s own immune system. Neuralgic Amytrophy is typically characterized by a sudden or acute onset of severe pain without a defined injury. Some triggers known to at times initiate the autoimmune cascade are recent infection, exercise, surgery, pregnancy, vaccination, stress, and even minor injury.
Hereditary Neuralgic Amytrophy
There is also a hereditary version called Hereditary Neuralgic Amytrophy that is an autosomal dominant hereditary trait as a result of a mutation (PMP22 deletion) in the SEPT9 gene that predisposes these patients to these attacks at a younger age and with increased frequency. These patients are also much more susceptible to pressure palsies, meaning sleeping with the arm in an unusual position may trigger the process much more easily in these patients. In our experience, the scope and number of nerves involved in Neuralgic Amyotrophy can be highly variable from having just one isolated nerve (mononeuritis) to multiple nerves and locations (mononeuritis multiplex) depending on the nature and extent of the presumed autoimmune process. Many of these patients will have concurrent shoulder pathology develop after a Neuralgic Amyotrophy attack-the most common are frozen shoulder, rotator cuff pathology, and unstable shoulder.
Suprascapular Nerve Dysfunction
One of the most common nerves involved in pain and dysfunction is the suprascapular nerve. The suprascapular nerve takes its origin from the C5, C6, and sometimes the C4 levels at the superior trunk and supplies sensation to the shoulder joint and surrounding tissues as well as power to the supraspinatus and infraspinatus portions of the rotator cuff. Because of its location and route the suprascapular nerve is particularly susceptible to injury. For instance, it can be injured following a clavicle fracture (collarbone). Because it makes a sharp turn at the suprascapular notch, it can also be injured from acute trauma that suddenly pulls down or up on the shoulder girdle such as fall from a height, contact sports, motor vehicle accident, etc.
There is also considerable variability in the size and shape of the suprascapular notch and this may also predispose some patients to suprascapular nerve injury. The suprascapular nerve can also be stretched with the extremes of motion as in overhead and repetitive sports: volleyball, swimming, baseball, tennis, etc. The use of crutches can also create traction injury to the suprascapular nerve. Based on its location, surgery near the nerve as in rotator cuff repair, clavicle surgery, labrum repair, and unstable shoulder repair can injure the nerve if the surgeon is not fully familiar with the location and position of the nerve. The suprascapular nerve may also be compressed (pinched) by anything that reduces the available space for the nerve such as tumors, bone fragments, or a ganglion cyst as seen in with SLAP tears and posterior labrum tears. Because the suprascapular nerve is relatively tethered at the suprascapular notch, large and massive rotator cuff tears particularly with retraction can also result in traction or stretching of the nerve. A better look at the anatomy of the suprascapular nerve is available here.
Depending on the mechanism of injury and duration of symptoms, patients may experience a variety of symptoms ranging from severe pain in the neck, shoulder blade, suprascapular nerve injury, and posterior shoulder to just a mild ache with offending activities. Sometimes the motor portion of the nerve is preferentially involved resulting in painless muscle wasting of the supraspinatus and infraspinatus.
The diagnosis can be suspected based on the clinical history and examination and is typically confirmed with further diagnostic tests. An EMG/NCV or electromygraphic study helps localize the nerve involvement as well as provide useful information about the type of injury and prognosis. Although the diagnostic criteria for EMG study of the suprascapular nerve have been well defined, we find the quality of EMG studies to be highly variable and recommend patients consult us for referral to an EMG specialist with significant experience and expertise in evaluating the brachial plexus and suprascapular nerve rather than have to repeat the test. We may also recommend advanced imaging of the shoulder and brachial plexus (MRI with or without contrast) depending on the root cause and clinical suspicion.
Treatment primarily depends on the cause of nerve injury as well as duration and severity. For mild symptoms without significant nerve conduction block and no other shoulder pathology, a regimen of physiotherapy for scapular control and stabilization as well as avoidance of offending activities can be very successful. Some patients may also benefit from a selective block of the suprascapular nerve with corticosteroids both as a confirmatory diagnostic test and often as a therapeutic maneuver as well. For patients with refractory symptoms or who have associated pathology (rotator cuff tear, frozen shoulder, unstable shoulder, labrum tear, ganglion cyst, etc.), our preferred approach is an arthroscopic decompression of the suprascapular nerve (keyhole surgery or minimally invasive surgery) combined with arthroscopic treatment of the associated pathology. We developed and published an arthroscopic technique for decompression of the suprascapular nerve.
If you are suffering from poorly characterized or difficult to diagnose shoulder pain consider the possibility that it may be due to nerve pain and schedule a consultation with an experienced specialist.