A pinched nerve is caused by some anatomical structure putting pressure on a nerve and impairing its function. This problem may occur in many different areas of the body. The most common places are those in which a nerve must travel through a small space. Examples include the region where the nerve roots exit the spine called the intervertebral foramen, and the carpal tunnel at the wrist, where a nerve must travel through a tunnel created by the wrist bones and ligaments.
A pinched nerve may go by several different names. It may be called nerve compression, entrapment, or impingement. Many problems involving pinched nerves will be called syndromes. Examples include carpal tunnel syndrome, thoracic outlet syndrome, and piriformis syndrome. If the nerve is pinched right near its root where it attaches to the spinal cord it is often called a radiculopathy.
The nerves that exit the spine and go down the upper limb and lower limb are gathered together in groups. Each group of nerves is called a plexus. In the neck region the nerves that leave the neck and go down the upper arm make up the brachial plexus. In the low back region, the nerves that go down the leg may come from the lumbar plexus or the sacral plexus. If a nerve is pinched where it is part of a plexus, it may be called a plexopathy. If the nerve is pinched farther along its length after it has left the plexus it is called a neuropathy.
A nerve is responsible for carrying two different types of signals. It carries sensory information, such as sensations of heat, pressure, texture, pain, or body position back to the spinal cord where that information will eventually be transmitted directly to the brain. These sensory signals that travel through the nerves are called afferent signals. A nerve also carries motor signals from the brain and spinal cord that tell the muscles when and how much to contract in order to create movement in the body. These motor signals that go from the brain and spinal cord out to the muscles are called efferent signals. When a nerve is pinched it may cause dysfunction with either the sensory (afferent) or motor (efferent) signals.
Causes & symptoms
A pinched nerve may occur from a direct blow. Most people are familiar with this sensation when they bang their elbow on a hard surface and get a sharp pain or prickling sensation down the arm. The symptoms of this kind of pinched nerve are usually very short-lived and are not a significant problem unless the force of the impact was severe.
What is much more common is the sensation of small amounts of pressure on the nerve from such adjacent structures as bones, muscles, tendons, and ligaments. This pressure most often occurs when the nerve has to travel through a small space between these structures. The nerve may get compressed with a small amount of pressure for a long period of time. It is the long time period of pressure on the nerve that causes the most damage. In many cases these long periods of pressure are related to the person's job. Occupations in which a person must hold the wrist, forearm or shoulder in one position for long periods of time and/or perform repetitive movements have a high rate of workers with pinched nerve syndromes. Dental hygienists, keyboard instrumentalists, violinists, data entry workers, assembly line and construction workers, and professional athletes are examples of workers at risk for pinched nerve syndromes.
When pressure is placed on the nerve a person may feel a variety of different symptoms. Paresthesia (the sensation of pins and needles) is often felt first. The sensations of paresthesia are usually felt anywhere along the nerve from the site of compression toward the far end of the extremity. Symptoms may also go from the site of compression toward the spinal cord, but it is not as common. In addition to paresthesia sensations, a person with a pinched nerve may also feel sharp, shooting pain, or pain that feels like an electrical shock going down the extremity. All of these symptoms are from impairment of the afferent (sensory) nerve signal transmission. The sensation is not necessarily near the area where the pressure is occurring.
Motor (efferent) signals can also be impaired from nerve compression. This will most likely show up as muscle weakness or problems with coordination. For example, people with carpal tunnel syndrome will frequently report losing grip strength. This is because the nerve has been compressed and signals are not getting through to the muscles of the hand that produce the grip.
Most pinched nerve conditions can be diagnosed with physical examination. The practitioner will take a thorough history, including an occupational history, and investigate the nature of the signs and symptoms to see if they indicate the likelihood of nerve compression. A number of physical examination tests may also be performed to see if nerve compression is aggravated with specific movements or pressure in certain areas. In addition to physical examination and information from the patient's history, nerve conduction tests may be run to see if the nerves are transmitting signals at the proper rate. If a nerve compression problem exists, there will be a slowing in the velocity of signal transmission in that nerve and it will likely be detected by the nerve conduction velocity test.
As of 2003, diagnostic imaging is being increasingly used to aid in the diagnosis of nerve entrapment and compression syndromes. Recent refinements in ultrasound and magnetic resonance imaging (MRI) provide doctors with detailed pictures of the anatomy of peripheral nerves and the changes that take place in them with compression syndromes.
Alternative therapy practitioners who specialize in such manual therapy methods as chiropractic, osteopathy, or massage therapy will look closely at the mechanical factors in the region of pain to identify what is pinching the nerve. If it is determined that the nerve is being compressed by some structure like a muscle that is pressing on the nerve, then therapy will be aimed at reducing tightness in that muscle so that it no longer presses on the nerve. This will generally be done through a variety of soft tissue therapy methods. In some instances there are other postural or mechanical distortions that may lead to nerve compression, and those will be addressed through manual therapy or various movement retraining methods.
Treatment will also focus on changing mechanical factors that may have led to nerve compression. For example, in carpal tunnel syndrome it is often some repetitive use activity that has led to the problem. If that activity can
Acupuncture can be quite helpful in treating pinched nerves since it has been shown to be a very effective method for producing pain relief. The primary goals of an acupuncture treatment will be both to reduce pain sensations and to get proper energy moving along the pathways that have been impaired. Needles will be inserted in areas that will help encourage proper neurological flow through the involved area. Acupuncture with electrical stimulation of the needles may also be used for treating pinched nerves.
In addition to acupuncture, other approaches from traditional Chinese medicine may be used. Both topical and oral herbal preparations may be used to help restore proper function and address any underlying causes of the pinched nerve symptoms. Cupping may be used to help free soft tissue restrictions that may be compressing the nerve structures in the area.
Traditional allopathic treatment for pinched nerves will also focus on the site of nerve compression and try to manage the symptoms first through conservative therapy. Oral medications may be given to relieve pain or reduce any inflammation that may be contributing to the nerve compression. Physical therapy may be used to help address any mechanical factors that may be contributing to the nerve compression. Physical therapy approaches are likely to include stretching, joint mobilization, soft tissue treatments, or such other modalities as ultrasound to address the causative factors of the nerve compression. Splinting is an additional conservative approach to nerve compression syndromes.
Depending on where the nerve compression is located, surgical treatment may sometimes be necessary. Surgery is often performed for such common nerve compression problems as carpal tunnel syndrome and thoracic outlet syndrome. Most of these surgical procedures will be aimed at relieving pressure on the affected nerve.
Some newer allopathic treatments that are used to relieve the pain of pinched nerve syndromes include low-level laser therapy (LLLT) and transcutaneous electrical nerve stimulation (TENS). In LLLT, a continuous-wave red-beam laser is aimed at acupuncture points on the affected area. In TENS, the affected nerve is stimulated with high-frequency electrical signals, which disrupt the transmission of pain impulses along the nerve so that the pain is no longer felt. Both these approaches give good results in treating pinched nerve syndromes, as they are noninvasive and painless.
In some cases in which the pinched nerve is related to the patient's job, a change of occupation may be necessary.
Most problems with pinched nerves will be resolved as soon the pressure on them is released. If the symptoms have been present for a long time, the relief of the condition may not be immediate. The longer the pressure has been applied, the longer it is likely to take for the symptoms to be resolved.
Most pinched nerve conditions can be avoided with proper body mechanics. Repetitive motions of the upper extremity are notorious for causing pinched nerves in several places, and it is wise to make sure a person is conditioned for the level of activity he or she is engaging in so as to prevent this from occurring. The individual should also be careful of activities that might put pressure on nerves for long periods. For example, nerves can be compressed in the shoulder region from the wearing of heavy backpacks or handbags for long periods.
Beinfield, H. Between Heaven & Earth: A guide to Chinese Medicine New York: Ballantine, 1991.
Butler, D. Mobilisation of the Nervous System. London: Churchill Livingstone, 1999.
Dawson, D., M. Hallet, and A. Wilbourn. Entrapment Neuropathies. Philadelphia: Lippincott-Raven, 1999.
Hammer, W. Functional Soft Tissue Examination and Treatment by Manual Methods, Second Ed. Gaithersburg, MD: Aspen, 1999.
Maciocia, G. Foundations of Chinese Medicine. London: Churchill Livingstone, 1989.
Stux, G. Basics of Acupuncture. New York: Springer-Verlag, 1991.
Anton, D., J. Rosecrance, L. Merlino, and T. Cook. "Prevalence of Musculoskeletal Symptoms and Carpal Tunnel Syndrome Among Dental Hygienists." American Journal of Industrial Medicine 42 (September 2002): 248-257.
Becker, J., D. B. Nora, I. Gomes, et al. "An Evaluation of Gender, Obesity, Age and Diabetes Mellitus as Risk Factors for Carpal Tunnel Syndrome." Clinical Neurophysiology 113 (September 2002): 1429-1434.
Gerritsen, A. A., H. C. de Vet, R. J. Scholten, et al. "Splinting vs Surgery in the Treatment of Carpal Tunnel Syndrome: A Randomized Controlled Trial." Journal of the American
Naeser, M. A., K. A. Hahn, B. E. Lieberman, and K. F. Branco. "Carpal Tunnel Syndrome Pain Treated with Low-Level Laser and Microamperes Transcutaneous Electric Nerve Stimulation: A Controlled Study." Archives of Physical Medicine and Rehabilitation 83 (July 2002): 978-988.
Nathan, P. A., K. D. Meadows, and J. A. Istvan. "Predictors of Carpal Tunnel Syndrome: An 11-Year Study of Industrial Workers." Journal of Hand Surgery 27 (July 2002): 644-651.
Roquelaure, Y., J. Mariel, S. Fanello, et al. "Active Epidemiological Surveillance of Musculoskeletal Disorders in a Shoe Factory." Occupational and Environmental Medicine 59 (July 2002): 452-458.
Spratt, J. D., A. J. Stanley, A. J. Grainger, et al. "The Role of Diagnostic Radiology in Compressive and Entrapment Neuropathies." European Radiology 12 (September 2002): 2352-2364.
Werner, R. A., and M. Andary. "Carpal Tunnel Syndrome: Pathophysiology and Clinical Neurophysiology." Clinical Neurophysiology 113 (September 2002): 1373-1381.
American Academy of Medical Acupuncture (AAMA). 4929 Wilshire Blvd., Suite 428, Los Angeles, CA 90010. (323) 937-5514. <www.medicalacupuncture.org>.
American College of Occupational and Environmental Medicine (ACOEM). 1114 North Arlington Heights Road, Arlington Heights, IL 60004. (847) 818-1800. <www.acoem.org>.
American Physical Therapy Association (APTA). 1111 North Fairfax Street, Alexandria, VA 22314. (703)684-APTA or (800) 999-2782. <www.apta.org>.
Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health (NIOSH). (800) 35-NIOSH. Fax: (513) 533-8573. <www.cdc.gov/niosh>.
Rebecca J. Frey, PhD