Low Back Pain: Getting to the Root of the Problem

A persistent ache in the lower back. Shooting pains down the legs. Muscles so tight you can't even stand up straight. For the more than 65 million Americans who suffer from low back pain every year, the symptoms come in different forms, but the problem is frequently the same: a nerve root near the spine is irritated. "It's actually quite simple," said Robert F. Heary, MD, Neurosurgery Today Spine Editor and a neurosurgeon in New Jersey. "In about 90 percent of all low back pain cases, a nerve that travels from the spinal cord through the bones of the spine gets pinched or irritated, the muscles tense up and the patient experiences low back pain. The solution depends on why the nerve is irritated in the first place."

The spinal column is an intricate network of nerves, discs and bones. The spinal cord begins in the brain and is protected by the spinal column as it runs most of the way down the back. Every movement and function of the body is controlled by the spinal cord. Motor nerves lead out of the spinal cord to control movement in the body while sensory nerves enter into the spinal cord communicating messages from the body back to the brain. Together, the motor and sensory nerves form more than 50 nerve roots, which run through holes, called foramina, in the bones of the spinal column. Each one of these nerve roots has the potential to become irritated and cause back pain.

A soft flexible disc that acts as a shock absorber and further protects the spinal cord separates each of the bones, or vertebra, in the spine. These discs have a rigid outside rim, but are soft and gel-like inside. The discs can bulge and press on a nerve root, causing irritation.

"Activity, stress or a mechanical problem in the spine can cause one of the discs to bulge and become misshapen just as a rubber tire might with pressure on it," Dr. Heary said. "When this happens, the disc may pinch or put pressure on a nerve root and the patient experiences pain. This is what frequently happens in a mild or moderate case of low back or leg pain."

Occasionally, the disc will bulge to the point where it herniates or ruptures and puts even greater pressure on the nerve root. In the lower back, the nerve roots lead to the legs and irritation may cause not only back pain, but also pain that radiates down one or both of the legs. There also can be muscle weakness, numbness or changes in the reflexes in the legs if a nerve root in the lumbar spine is irritated.

"It's common to develop a back sprain like a sprain in the ankle," explained Stewart Dunsker, MD, President Elect of the American Association of Neurological Surgeons and a neurosurgeon practicing in Ohio. "Even mild episodes of low back pain usually involve some sort of irritation of the nerves in the spine. The key to that initial treatment is to relieve the nerve irritation."

Although low back pain can be quite debilitating and severe to patients, in 90 percent of cases the pain improves without surgery. However, 50 percent of all patients who suffer from an episode of low back pain will have a recurrent episode within one year. If low back pain occurs with a fever or can be related to a specific recent injury, like a car accident, fall or sports injury, patients should call their primary care physician (PCP) immediately or visit the emergency room. If not, patients can begin conservative treatment at home for two or three days.

"In the first couple of days the goal is stop the irritation of that nerve," Dr. Dunsker said. "Patients should take anti-inflammatory medications like ibuprofen, not aspirin or acetaminophen, and restrict activities for a few days."

Because the nerve root is being irritated, patients can either get relief or feel intense aggravation in various positions like sitting, lying, or standing. It is important to find a position that relieves the pain, Dr. Dunsker said. If the low back pain gets worse or does not improve after two or three days of home treatment, a primary care physician (PCP) should be the next step. The PCP can evaluate the patient for any serious conditions. Once those are ruled out, the doctor can do a series of movement tests in the office to determine which nerve root is being irritated. If there are signs the nerve root is being compromised, the primary care physician can prescribe medications to relieve the pain, swelling and irritation and may also recommend limited activities. If these treatment options do not provide relief within two weeks, it may be time to consider other options.

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