Ask Dr Gary: Pain has long reach

I'm 38 years old and have continuous pain in my left shoulder and shoulder blade. Any movement and my arm goes numb. Even when I rest my arm on the armchair it goes numb down the whole arm, and I get extreme pain in the shoulder itself. What's happening? - DS

Pain radiating down a limb can be a sign of an injured nerve. The nerve can be pinched as it leaves the spine and travels through the shoulder and down the arm. The compression can be from arthritic changes in the bones of the spine, or from the nerve being compressed between layers of muscles, tendons and ligaments.

Any simple swelling in the shoulder, such as from overuse or a rotator cuff injury, can also press on the brachial plexus, a tangle of nerves that courses through the shoulder and eventually supplies sensation and movement to the arm, forearm and hand.

When the pain follows the path of the nerve from the spine outwards, we call it "radicular" pain, from the Latin for root. Radicular pain usually subsides as the inflammation dies down. Anti-inflammatories like ibuprofen and analgesics like paracetamol are used to treat it. Injected steroids can reduce inflammation in some cases. In others, physiotherapy and splints are used.

In very rare cases, the nerve is pinched so severely it stops working, causing severe pain, weakness and even loss of control of affected muscles. They may be candidates for surgery at this point, though its worth clarifying what the goal is: relief of pain or preservation of muscle function.

Other causes of shoulder pain and arm numbness can be tumours, tendon inflammation, arthritis, rotator cuff injuries. Even blood clots can cause intense shoulder or arm symptoms.

Your GP is the right person to start the work-up. Some cases may require MRI or nerve conduction tests. Hope this helps explain things a bit. Let me know how it turns out.

Gary Payinda, MD, is an emergency physician who would like to hear your medical questions. Email drpayinda@ gmail.com. This column gives general information and is not a substitute for the advice of your doctor.