ADRSupport Community - Aging of the Spine

A succinct summary of the process...
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November 04, 2007

Effects of age can result in back pain

By DR. YONG H. TSAI
MANAGING PAIN

In the past six months, Tom, a 52-year-old police officer, has developed moderate pain at his right buttock radiating to his right calf and numbness of his right foot.

His MRI scan revealed a dehydrated disc with moderate sized right protrusion, as well as bilateral facet arthropathy and thickening of the ligmentum flavum. The MRI also disclosed a mild central canal stenosis and moderate foraminal narrowing on the right. Tom asked me what the report meant, and exactly what had happened to his spine.

The spine is a flexible curved group of backbones made up of 33 vertebrae separated by spongy discs and connected by facet joints. Behind the vertebrae are bones that form a canal, which house nerves and the spinal cord.

Nerve roots are located between each pair of lumbar vertebrae, and emerge from the spinal canal through an opening in the bone (foramen). The sciatic nerve consists of two nerve roots, located at the fifth lumbar vertebra (L5) and first sacral vertebra (S1), which branch out from each hip, down the leg, and to the feet.

A spinal disc is circular and filled with a thick gel at the center, called the nucleus pulposus, and tire-like fibers, called the annulus fibrosus, which surround the nucleus. The gelatin substance found in the nucleus consists of collagen, proteoglycans (PG) and water. The water binds itself with the PG, and creates a cushion that acts like a shock absorber for the vertebrae during jarring movements such as walking, jumping, and running.

As we age, the amount of PG and water in our nucleus diminishes. Then, the nucleus becomes drier and flakier. The fibers surrounding the nucleus become stiff and easily break.

Ruptured or cracked fibers allow the nucleus materials to move backward. With repetitive bending forward, the pressure sustained by the discs further pushes the nucleus toward the back. This process causes bulged, protruded or even herniated discs, frequently responsible for pinching nerves, particularly in L5 and S1.

When discs degenerate, the space within the vertebrae narrows. This process puts more pressure on the facet joints, and in turn causes osteoarthritis in them, just like osteoarthritis of the knee or hip.

Disc degeneration and herniation, along with facet arthritis and ligament hypertrophy, further decrease the space within the canal. This condition is called spinal stenosis. Spinal stenosis can occur either in the spinal canal or at the foramen (bony opening) of the nerve root.

After I explained the spine and discs to Tom, he seems to have a better idea about his back structure. He then asked what really causes his back and calf pain, and numbness of his feet. Stay tuned, as we address Tom again in the next column.

Dr. Yong H. Tsai is board-certified in rheumatology, allergy and clinical immunology and has been practicing in this area since 1993. Send questions to Dr. Tsai in care of accent@news-jrnl.com.
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