Nerve Entrapment

Definition

Nerve entrapment occurs when a nerve becomes compressed by muscles or tissues around it, resulting in pain, numbness, or loss of function.

Demographics

The incidence of nerve entrapment varies by the type of condition. Carpal tunnel syndrome, in which a nerve is compressed as it passes through a narrow space in the wrist, is the most common is newly diagnosed nerve entrapment syndrome. Each year in about three in every 1,000 individuals in the United States develop carpal tunnel syndrome, and approximately 50 of every 1,000 individuals have carpal tunnel at any one time. Whites are more likely than African Americans to have carpal tunnel syndrome, and it is about three times more common in women than it is in men. It is most likely to develop in individuals between the ages of 45 add 60.

Estimates suggest that between 15% and 40% of individuals will experience sciatica, in which a nerve in the lower back is compressed, at some time in their life. Most of these cases, however, resolve without medical treatment. Each year between 1% and 5% of individuals will experience sciatica.

Description

Nerves run throughout the human body. The nervous system allows the human body to feel sensations such as heat and control movements such as walking and grasping. The brain is the center of the nervous system, and all nerves lead to the spinal cord, and through the spinal cord to the brain. The brain processes the input it receives from all of the nerves in the body.

Nerve entrapment is a condition in which a nerve is compressed by bone, muscle, tendon, or other tissues that surround it. The compressed nerve cannot function and send electrical impulses correctly. This leads to a number of symptoms including numbness, weakness, and pain.

Some of the most common nerves that become entrapped are nerves of the hand (such as in carpal tunnel syndrome), the lower back (such as in sciatica) and the elbow. However, nearly any nerve in the body can become compressed. Athletes are more likely to experience compression of the nerves that are in areas subjected to repetitive movements or repeated trauma. For example, tennis players may be more likely to experience compression of nerves in the elbow due to the repeated friction caused when swinging a racket.

Risk factors

The risk factors for nerve entrapment vary somewhat by the location of the problem. Women are at greater risk for carpal tunnel syndrome than men. It is not entirely clear why this is the case; however, some experts believe that it is due to women having a smaller carpal tunnel to begin with, making even small amounts of swelling more likely to cause symptoms.

Obese individuals are a higher risk for nerve entrapment. There is some debate over whether a job that requires repetitive movements or involves high levels of vibration (such as using a jackhammer) increases the risk of nerve entrapment. Athletes who participate in sports or recreational fitness activities that require repetitive movements such as tennis or ballet may be at an increased risk of nerve entrapment. Elite athletes who practice movements thousands of times may also be at increased risk. Some experts believe that repetitive tasks put individuals at greater risk of nerve entrapment, but others provide evidence that individuals who participate in these types of activities are at no greater risk than the general population. Research is ongoing to resolve this debate.




Several common examples of nerve entrapment affecting various parts of the body.

KEY TERMS
Corticosteroids—
A group of hormones that are sometimes used as an injection to treat inflammation.
Magnetic resonance imaging (MRI)—
MRI uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.
Nonsteroidal anti-inflammatory drugs (NSAIDs)—
A class of drugs that is used to relieve pain, and symptoms of inflammation, such as ibuprofen and ketoprofen.

Causes and symptoms

Nerve entrapment is caused when tissues, bones, or muscles around a nerve push against the nerve and compressing it. This compression makes the nerve unable to function correctly. Nerve compression can occur for a number of reasons. In many cases, the cause is inflammation of the tissue in the surrounding area. When tissue is inflamed it expands or swells, and pushes against anything in the area. When a nerve is nearby, the inflamed tissue can press up against it, causing compression.

Tissue can become inflamed for many reasons. Overuse is one of the most common causes. Extremely repetitive movements can cause overuse of joints, tendons, and muscles, and the repeated friction between various internal structures can cause inflammation. Poor posture can also cause nerve entrapment, as this can causes areas of the body to move in ways that were not intended, placing stress on them.

The symptoms of nerve entrapment can vary somewhat depending on the nerve affected and the individual. In general, compression of a nerve causes feelings of tingling (similar to the “pins and needles” feeling that occurs when a hand or foot “falls asleep”). A feeling of numbness is common, and the affected area may not be able to fully feel normal sensations. In many cases, the area will be weak, and in some cases, the compressed nerve may cause slight twitching movements. In many cases, nerve compression causes a moderate to severe level of pain. This pain may be worse at night or upon waking up in the morning.

Diagnosis

Nerve entrapment is diagnosed using a history of the symptoms present in conjunction with one or more diagnostic tests.

Magnetic Resonance Imaging (MRI) uses a large magnet and radio waves to create pictures of the internal structures of the body. This can help doctors look for various kinds of damage, and can help rule out other possible problems that have symptoms similar to nerve entrapment.

One common way to diagnose nerve entrapment is through tests that examine how well the nerve thought to be compressed is transmitting impulses. Compressed nerves do not transmit electrical signals as effectively as nerves that are not compressed. A nerve conduction study uses electrodes placed on the skin to send a test impulse through the affected nerve. How quickly the impulse moves through the nerve is then measured.

Treatment

The majority of cases of nerve entrapment can be treated successfully with noninvasive interventions. The first treatment typically suggested for nerve entrapment is to rest the problem area. This can help reduce swelling that will, in turn, reduce the compression on the nerve. It is especially important to stop doing any of the activities that may have caused the nerve entrapment. For example, if the compressed nerve occurs in the elbow it is advisable to stop playing tennis to give the area time to heal.

Physical therapy may be recommended, depending on the area of the compressed nerve. Physical therapy can provide strengthening exercises for the muscles around the compressed nerve that can take some of the pressure off the problem area. In some cases, posture can be improved through physical therapy, which may be able to help nerve entrapment that occurs in the back.

Nonsteroidal anti-inflammatory medications (NSAIDs) such ibuprofen may help reduce the swelling and can treat any pain associated with the compressed nerve. For individuals who have a lot of pain caused by nerve entrapment that is not adequately treated by NSAIDs, corticosteroid injections may be recommended. Corticosteroid injections are given directly to the affected area and are very successful in reducing swelling.

QUESTIONS TO ASK YOUR DOCTOR
  • Would nighttime splinting help reduce my symptoms?
  • Is it likely that taking an anti-inflammatory could help improve my condition?
  • Is it likely that surgery will be necessary for me?
  • How soon will I be able to resume by usual sports and fitness activities?
  • Are there any exercises or stretches I can do to improve my condition?
  • Do I need a referral to a specialist?

Prognosis

The prognosis for nerve entrapment is generally quite good. The significant majority of individuals can find relief through a combination of rest, splinting, and anti-inflammatory medications. In a minority of cases, surgery is required. Surgery is generally quite successful at reducing the compression of the nerve and providing relief. In cases of nerve entrapment that are left untreated or for which treatment was not successful, permanent nerve damage can occur.

Prevention

There is no certain way to prevent nerve entrapment. However, some things can help reduce the risk. Maintaining a healthy weight can help reduce pressure on nerves. Regular strength training, especially for areas likely to be affected such as the back, can help increase muscle tone, improve posture, and relieve pressure that may lead to nerve compression. Maintaining good posture in general can help prevent nerve entrapment in the spine. Avoiding doing repetitive activities and taking frequent breaks to stretch can help prevent some kinds of nerve entrapment, especially carpal tunnel syndrome.

Resources

BOOKS

Akuthota, Venu, and Herring, Stanley A., eds. Nerve and Vascular Injuries in Sports Medicine. New York: Springer, 2009.

Fonseca, David J., and Martins, Joanne L., eds. Sciatic Nerve: Blocks, Injuries, and Regeneration. Hauppauge, NY: Nova Science, 2012.

Michael-Titus, Adina, Patricia Revest, and Peter Shortland. The Nervous System: Basic Science and Clinical Conditions, 2nd ed. New York: Churchill Livingstone, 2010.

PERIODICALS

Atroshi, Isam, et al. “Incidence of Physician-Diagnosed Carpal Tunnel Syndrome in the General Population.” Archives of Internal Medicine 171, no. 10 (May 23, 2011): 943–4.

Kovacevic, David, Michael Mariscalco, and Ryan Goodwin. “Injuries About the Hip in the Adolescent Athlete.” Sports Medicine and Arthroscopy Review 19, no. 1 (March 2011): 64–74.

Kox, Ida K., and Susan E. Mackinnon. “Adult Peripheral Nerve Disorders: Nerve Entrapment, Repair, Transfer, and Brachial Plexus Disorders.” Plastic and Reconstructive Surgery 127, no. 5 (May 2011): 105e–18e.

WEBSITES

Hanna, Amgad Saddik, et al. “Nerve Entrapment Syndromes.” Medscape. November 11, 2015. http://emedicine.medscape.com/article/249784-overview (accessed January 20, 2017).

“Pinched Nerve.” Mayo Clinic. March 1, 2016. http://www.mayoclinic.org/diseases-conditions/pinched-nerve/basics/definition/con-20029601 (accessed January 20, 2017).

ORGANIZATIONS

American Medical Society for Sports Medicine, 4000 W 114th St., Ste. 100, Leawood, KS, 66211, (913) 327-1415, Fax: (913) 327-1491, http://www.amssm.org .

American Neurological Association, 1120 Route 73, Ste. 200, Mount Laurel, NJ, 08054, (856) 380-6892, info@myana.org, https://myana.org .

American Orthopaedic Society for Sports Medicine, 9400 W Higgins Rd., Ste. 300, Rosemont, IL, 60018, (847) 292-4900, Fax: (847) 292-4905, http://www.sportsmed.org .

Tish Davidson, AM

  This information is not a tool for self-diagnosis or a substitute for professional care.