Pinched Nerve Health Article

Definition

A pinched nerve is a general term that describes an injury to a nerve or group of nerves. The damage may include compression, constriction or stretching. Nerves that pass near or through bones or other rigid tissues are most susceptible to pinching. Pinched nerves result in numbness, pain, burning and tingling sensations radiating out from the affected area.

Description

Pinched nerves can be grouped into two types depending on where they occur in the body. Pinched nerves can occur within or in the vicinity of the vertebral column. For example, herniation of vertebral discs causes pain along the pathway of the nerve that is affected. Similarly, stenosis, or narrowing, of the vertebral column puts pressure on nerves traveling through the vertebrae. Another group of pinched nerves are referred to as nerve entrapment syndromes and they affect peripheral nerves, most commonly in the arms.

At least 80% of all herniated discs occur in people between the ages of 30 and 50. Between these ages, the tough outer core of the vertebral discs weakens and the soft gel-like inner core, which is under pressure, can more easily squeeze through weakened areas. After age 50, the inner core begins to harden, making herniation of discs less common. The amount of pain and discomfort resulting from a herniated disc varies depending on which disk has herniated and the amount of rupture. One of the most common problems associated with herniated discs is sciatica.

Nerve entrapment syndromes refer to a particular type of pinched nerve, in which peripheral nerves are chronically compressed resulting in pain or loss of function in an extremity. The most common nerve entrapment syndromes affect the median, ulnar and radial nerves of the arms. Nerve entrapment syndromes are extremely common, accounting for about 10–20% of all cases seen in neurosurgical practices. The most common entrapment syndrome is carpal tunnel syndrome. Cubital tunnel syndrome of the ulnar nerve, which runs down the arm and through the elbow, also occurs frequently.

Causes and symptoms

A nerve can be thought of as a wire encased in insulation that carries electrical information from one part of the body to another part. When the insulation or the wire itself becomes damaged the electrical signal does not move along the nerve efficiently or, in severe cases, the signal is not transmitted at all. The brain interprets this faulty transmission as pain, numbness or burning. Several different types of damage can occur to nerve cells that cause a disruption in the transfer of electrical signal. Compression or pressure on a nerve in one area will result in symptoms such as numbness or tingling in the region from which the nerve should be sending signals. The myelin sheath, which covers the nerve and is analogous to the insulation covering an electrical wire, can be damaged by scarring, in effect causing a short circuit of the nerve. Scar tissue hinders movement of a nerve in its tissue bed as the body moves and compromises the ability of the nerve to function properly, either by stressing the nerve fibers themselves or by impairing the blood supply to the nerve cell. Nerves can also be pulled or stretched, which constricts the nerve fibers. This is called a traction of the nerve and results in a decreased electrical flow through the nerve. The brain interprets the slow electrical signal as numbness, pain, or tingling.

Pinched Nerves in the Spine

Herniated discs are the most common reason for a pinched nerve along the vertebrae. This condition occurs when the gel-like core of a vertebral disc (nucleus puposus) ruptures through the tougher outer section (annulus) of the disc. The extrusion puts pressure on the adjacent nerve root causing it to function improperly. The discs that most often suffer from herniation are those in the cervical spine and the lumbar spine because they are the most flexible.

Lumbar disc herniations usually occur between lumbar segments 4 and 5, which cause pain in the L5 nerve, or between lumbar segment 5 and sacral segment 1, which cause pain on the S1 nerve. Pinching of the L5 nerve causes weakness in the big toe and ankle and pain on the top of the foot that may extend up to the buttocks. Pinching of the S1 nerve causes weakness in the ankle and numbness and pain in the sole and side of the foot. If the sciatic nerve, which runs from lumbar segment 3 down the vertebral column, is pinched by a herniation, the resulting condition is known as sciatica and it can cause pain, burning or tingling in the buttocks and leg. Lumbar disc herniations often heal on their own and conservative treatments are used to provide some relief from symptoms and to aid healing. Such treatments include physical therapy, chiropractic manipulations, non-steroidal anti-inflammatory drugs, oral steroids and, in some cases, an injection of a steroid such as cortisone. In more severe cases, surgery to remove the pressure of the disc from the nerve is warranted. This is most often performed using microsurgical techniques.

Cervical disc herniations occur less frequently than lumbar disc herniations because there is less force in the cervical spine and less disc material between vertebrae. When nerve roots exiting the cervical spine are pinched, they can cause a radiculopathy, ora pain in the arm. Rarely, the nerves between the first and second or second and third cervical segments can be pinched. These nerves are sensory nerves and can cause chronic headaches. Usually cervical disc herniations heal on their own and conservative treatments are used to relieve symptoms and pain. These treatments include rest, non-steroidal anti-inflammatory drugs, physical therapy, chiropractic treatments and manual traction. Epidural injections of cortisone may also help relieve pain. Surgical techniques can also be used to remove the herniated disc from impinging on nerves.

Stenosis, or narrowing, of the spinal canal can cause a pinching of the spinal cord. This occurs commonly with age and may cause weakening of muscles or loss of coordination. Often symptoms develop slowly and worsen over a long period of time. Usually treatment for this condition requires surgery to relieve pressure on the spinal canal.