By Howard LeWine, M.D.
Q: What is a trapped nerve? How does it happen?
A: The term “trapped nerve” refers to a condition in which a nerve is compressed or pinched. This causes pain, numbness, weakness or other symptoms. There are many sites and causes of nerve compression. Here are some of the common ones:
A disc problem in the back or neck. Spinal discs can bulge or tear, pressing on nerves as they travel to and from the spinal cord; sciatica is a common example of a “trapped nerve” that may be due to disc disease.
Swelling in the wrist from fluid retention or arthritis. The median nerve travels through the carpal tunnel, a tight space in the wrist that is easily compressed by swelling in the joint.
Enlarged tissues. Growth of a lymph node, an abscess (an infection) or a tumor can compress a nearby nerve.
Injury. A nerve can be compressed by swelling, fracture or bleeding following trauma. Or the injury might be minor, such as simply leaning on your elbow. This can compress the ulnar nerve that travels just under the skin.
After reviewing your symptoms and performing a physical exam, your doctor can often tell which nerve is compressed. Some tests, such as magnetic resonance imaging (MRI) for disc disease, may be necessary to confirm the location of the nerve entrapment and the specific cause.
Treatment of an entrapped nerve depends on the cause. It may be as simple as wearing a wrist splint for carpal tunnel syndrome or not leaning on your elbows. Medications, such as anti-inflammatory drugs for arthritis, may improve symptoms of nerve compression. However, surgery may be recommended for if these other measures are not effective.
(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)