Shoulder Pain After a Stroke

Possible causes:

• shoulder subluxation
• adhesive capsulitis
• impingement syndrome
• rotator cuff injury
• complex regional pain syndrome
• irritation of the brachial plexus (the nerves that run from the neck, through the shoulder area, into the arm)
• bursitis
• any combination of the above

Shoulder Subluxation

–  the joint is partly dislocated, or in other words, there is decreased stability of the joint.  The shoulder joint depends significantly on the tension of the muscles surrounding the joint (rotator cuff muscles and deltoid especially), so when these muscles are paralyzed or partially paralyzed (paretic), the only remaining support of the joint are the ligaments, which often become stretched and don’t hold the shoulder snugly in it’s correct position.  Once these ligaments are stretched, there isn’t much that can be done to restore their proper tension at the shoulder joint (other than surgery), so prevention of subluxation is critical.

How to prevent or counteract subluxation?

The key here is PREVENTING subluxation.  If your arm is very weak, or flaccid, have your PT or OT help you obtain the right type of sling for your needs.  Wearing a sling for part of the day, when you are not using your arm for rehab exercises, can help to decrease the chances of shoulder subluxation.

The use of a sling that holds your elbow bent, and your arm across your stomach or chest is generally NOT recommended because it can lead to frozen shoulder and accentuate the development of contractures.  The use of a sling that has some kind of bulky portion in the armpit area is also NOT recommended, because it could displace the joint away from the body, increasing the risk or harm of subluxation.  See Arm Slings for more information on the various types available.

Part of the cause of shoulder subluxation in the hemiplegic shoulder is a downward rotation of the shoulder blade.  As far as I know, there is no sling on the market that can prevent or correct this “drooping” of the shoulder blade, which permits more stretching of the shoulder ligaments, and thereby contributes to subluxation.  You need to perform active scapula retraining exercises with a PT or OT.  And if your arm is very weak or flaccid,  you also need to keep your arm supported on the arm rest of your chair, or on your table or tray-table whenever you are sitting.

Treatment for subluxation pain with electrical stimulation:

Research supports the idea that using NMES (NeuroMuscular Electrical Stimulation) on certain muscles around the shoulder can help to decrease subluxation and improve the mechanics and the integrity of the joint, with an accompanying decrease in pain.  This can be done with a transcutaneous system, in which the electrical stimulation is provided through electrodes placed on the surface of the skin.  Or it can be accomplished through intramuscular systems, which use small devices implanted in the shoulder area.  Both forms of electrical stimulation have been shown to decrease shoulder pain related to subluxation.  However, the amount of use time required to obtain results is substantial…..usually up to 6 hours every day for about 6 weeks.  With this amount of use time, pain is often provoked from the electrical stimulation itself.  In fact, 30% of patients cannot tolerate using such a device (1).  The intramuscular system has the advantages of being implanted directly at the required location to stimulate muscle contraction, thereby decreasing the intensity of stimulation required, and resulting in less stimulation of nociceptors in the area (in other words, less pain).  It is also more easily applied by the patient at home once the electrodes are implanted; however it runs the small risk of infection that accompanies any invasive procedure. (1)

To find out more about NMES, read my article called “Electrical stimulation in Stroke Rehab.”

Frozen Shoulder – also known as Capsulitis, or Adhesive Capusilitis

This could, in a way, be considered the opposite of shoulder subluxation.  In frozen shoulder, the ligamentous capsule around the shoulder joint becomes fibrotic, and forms adhesions, thereby restricting the range of motion significantly.  The exact reason that some individuals develop frozen shoulder after period of immobility or inflammation, and others do not, is still not fully determined.  After a stroke, spasticity of the shoulder internal rotators could play a role in frozen shoulder.  The restriction of motion typically has a pattern.  The most limited motions are lifting the arm out to the side, and external rotation of the shoulder so that  the hand moves away from the stomach.  This condition is often painful, and very slow to improve.  Your options for treatment are range of motion interventions under the care of a physical therapist, and perhaps injection of steroid medications directly into the shoulder joint.  As with most conditions, prevention is the best treatment.  Avoid prolonged use of shoulder slings that keep your arm across your body, and be diligent with your range of motion exercises.

Impingement Syndrome and Rotator Cuff Injury

This refers to the compression of a tendon or ligament in the subacromial space, which is the space between the top of your humerus (upper arm bone) and the socket of your shoulder joint (or between the ball in the socket).  The most common structure that can be pinched in this space is the supraspinatus tendon, which is one of the 4 muscles that comprise the rotator cuff.   Repetitive pinching, or impinging of the supraspinatus tendon leads to inflammation and pain, and can eventually lead to tearing of the tendon (commonly called a torn rotator cuff).  Some other structures that can also be pinched and become inflamed in this space are: biceps tendon, subacromial bursa, and coracohumeral ligament.

The reason these structures (especially the supraspinatus tendon) are vulnerable to becoming pinched, or impinged, is that the mechanics of the shoulder can be disrupted from paralysis or partial paralysis of the muscle that control the shoulder.  Too much laxity of the joint (subluxation) or not enough laxity (from spasticity and/or developing frozen shoulder) can cause impingement when the arm is raised up overhead or out to the side (flexion or abduction).

• The most vulnerable position for impingement is lifting the arm out to the side and up, with your shoulder internally rotation (thumb pointing downward).  If you’ve ever heard of the “empty can exercise,”  THAT is the exact motion to avoid.  Overhead pulley exercises can also contribute to impingement, especially if the arm is not externally rotated (thumb pointing toward ceiling).  And you might also be careful about bearing weight through your affected elbow when sitting, which is a common position for those who have decrease trunk strength from hemiplegia.

Working with a physical or occupational therapist to improve the positioning and mechanics of your shoulder can help with impingement.  If you have adequate muscular control, retraining the way you move your shoulder blade, and avoiding slumped sitting positions can help.

Bursitis

As mentioned above, impingement syndrome can affect the bursa of the shoulder, which is a fluid filled sac that acts as a buffer between tendons and the bony parts of the shoulder.  When this bursa is repetitively pinched, it becomes inflamed, and is then called bursitis.  Bursa (fluid filled sac) + itis (inflammation) = bursitis.  Read the tips above for preventing and treating impingement.

Brachial Plexus Injury/Irritation (and other nerves)

The brachial plexus is the group of nerves that come from your neck and run down through your shoulder into your arm and hand.  Subluxation seems to be the culprit in this source of pain, as well.  Too much stretching on these nerves can cause pain and injury to the nerve, which displays itself in burning pain, numbness, and tingling in the arm or hand.  The axillary nerve is one of the branches of this brachial plexus that can often be overstreched.  So when shoulder subluxation is present, the joint is not drawn up into the socket as it should be, and too much stretch, or even a small of amount of stretch for too long, can injure the nerve.

This can be treated with similar interventions described above for subluxation.

Complex Regional Pain Syndrome (casualgia, shoulder-hand syndrome, reflex sympathetic dystrophy)

The source of pain in this condition is not well understood.  Theories include an exaggerated immune system response, or certain parts of the nervous system getting “stuck” in a hyper-responsive state.  It can occur after a significant nerve injury, or sometimes even after mild injuries to the soft tissue of the limb.  Symptoms usually include extreme burning pain, changes in skin temperature and color (sometimes alternating between warm and cold, and between red and white), changes in hair and nail growth, changes in perspiration (often sweaty), stiffness, and decreased strength.

Possible treatment for CRPS:

• Medications – your doctor might prescribe analgesics, antidepressants (amitriptyline for example), or anticonvulsants (Neurontin for example) to decrease the nerve type pain.
• Applying heat and cold
• Topical analgesics/creams – which contain medications such as lidocaine or a combination of ketamine, clonidine and amitriptyline.
• Physical therapy. ROM and gentle exercise are sometimes helpful in gradually restoring ROM and decreasing sensitivity to movement and pressure
• Sympathetic nerve-blocking medication. Injection of an anesthetic to temporarily block the pain signals from transmitting along the affected nerves.
• Transcutaneous electrical nerve stimulation (TENS) – small amounts of electrical simulation are thought to block the pain signals going to your brain, thereby decreasing your perception of pain.  To find out more about TENS, read my article called electrical stimulation.