Disc Surgery May Relieve Pain but Not Atrophy in Back Muscles
How are low back muscles linked with the discs located between the vertebrae? This is a question researchers are eagerly studying. They would like to identify types of exercise that would help patients with herniated discs.

Discs between the bones in the spine have two parts: the nucleus in the center, and an outer ring called the annulus. If the nucleus pushes completely through the annulus, it is called a disc herniation.

Most patients with low back pain from disc herniation also have muscle atrophy (wasting) in the back muscles. Weak and atrophied spine muscles may put these patients at increased risk of overload and more back pain.

Surgery is one way to treat disc herniation. The operation may relieve painful symptoms, but it doesn't always change atrophy of the muscles in the low back. Muscle atrophy and weakness can go on for months. The patient is often delayed in getting back to daily activities.

This study from the Nippon Medical School in Tokyo, Japan, focuses on one muscle group in the low back called the multifidus muscles. The primary job of this muscle group is to hold the spine steady during regular activities.

A small piece of the multifidus muscle was taken from both sides of the spine in 17 patients with disc herniations. The pieces of muscle were looked at under a microscope. The muscle cells were markedly different in the muscles examined on the same side as the disc herniation. Smaller fibers and changes in the shape of some muscle fibers were found. The researchers also checked the activity of the muscles using electromyography (EMG). The EMG changes were greatest in patients who showed the largest changes in the fibers of their multifidus muscles.

According to the authors, rehab exercises for lumber disc herniation should include tonic and dynamic exercises. During tonic exercises, the muscles contract at low level for a period of time. This builds muscle endurance. Dynamic exercises for the multifidus muscles involve exercises that move the trunk through a range of motion, requiring the multifidus muscles to hold the spine steady while moving. This builds the muscle fibers that are responsible for muscle power and quickness. Including both forms of exercise in a rehab program for disc herniation may help halt atrophy of the multifidus muscle fibers.
Kiyoshi Yoshihara, MD, et al. Atrophy of the Multifidus Muscle in Patients With Lumbar Disk Herniation: Histochemical and Electromyographic Study. In Orthopedics. May 2003. Vol. 26. No. 5. Pp. 493-495.