CONDITIONS

Degenerative disc disease

Degenerative disc disease is an age-related condition that happens when one or more of the discs between the vertebrae of the spinal column deteriorates or breaks down, leading to pain.

There may be weakness, numbness, and pain that radiates down the leg.

Despite its name, degenerative disc disease is not a disease, but a natural occurrence that comes with aging.

The rubbery discs between the vertebrae normally allow for flexing and bending of the back, like shock absorbers. In time, they become worn, and they no longer offer as much protection as before.

Causes

Intervertebral discs, also known as intervertebral fibrocartilage or spinal discs, provide the padding between the vertebrae of the spine. They have an elastic structure, made of fibrocartilage tissue.

The outer part of the disc is known as the annulus fibrosus. It is tough and fibrous, and it consists of several overlapping layers.

The inner core of the disc is the nucleus pulposus. It is soft and gelatinous.

The intervertebral discs cushion the stress when the spine moves or bears weight. They also help the spine to bend.

As people age, repeated daily stresses on the spine and occasional injuries, including minor, unnoticed ones, can damage the discs in the back.

Changes include:

• Loss of fluid: The intervertebral discs of a healthy young adult consist of up to 90 percent fluid. With age, the fluid content decreases, making the disc thinner. The distance between vertebrae becomes smaller, and it becomes less effective as a cushion, or shock-absorber.
• Disc structure: Very small tears or cracks develop in the outer layer of the disc. The soft and gelatinous material in the inner part may seep through the cracks or tears, resulting in a bulging or rupturing disc. The disc may break into fragments.

When the vertebrae have less padding between them, the spine becomes less stable.

To compensate, the body builds osteophytes, or bone spurs, small bony projections that develop along the edge of bones. These projections can press against the spinal cord or spinal nerve roots. They can undermine nerve function and cause pain.

Other problems include:

• a breakdown of cartilage, the tissue that cushions the joints
• a bulging disc, known as a herniated disc
• a narrowing of the spinal canal, or spinal stenosis

These changes can affect the nerves, leading to pain, weakness, and numbness.

Symptoms

Disc degeneration may cause no symptoms, or the pain may be so intense that the individual cannot continue with their daily activities.

The condition starts with damage to the spine, but in time, symptoms can affect other parts of the body. Symptoms usually get worse with age.

The discomfort can range from mild to severe and debilitating. It can lead to osteoarthritis, with pain and stiffness in the back.

The most common early symptom is usually pain and weakness in the back that radiates to another area.

If the damage is in the lower back, or lumbar spine, the discomfort may radiate to the buttocks and upper thighs. There may also be tingling, numbness, or both, in the legs or feet.

If the damage is in the neck area, or cervical spine, the pain may spread to the shoulder, arm, and hand.

There may also be instability in the spine, leading to muscle spasms in the lower back or neck, as the body tries to stabilize the vertebrae. This can be painful.

The individual may experience flareups of intense pain.

The pain may be worse when sitting, bending, lifting, or twisting. Walking, lying down, and changing position may help relieve it.

Risk factors

Age is the biggest risk factor, but some other factors can speed up the process of degeneration.

These include:

• obesity
• strenuous physical work
• tobacco smoking
• an acute or sudden injury, such as a fall

Degenerative disc pain can start when a major or minor injury leads to sudden and unexpected back pain, or it can present as a slight back pain that gets worse over time.

Diagnosis

The doctor will ask about symptoms, when and where the pain occurs, whether there is tingling or numbness, and which situations cause the most pain. They will also ask about any falls, injuries, or accidents.

A physical examination may assess for:

• Muscle strength: The doctor may check for atrophy, wasting, or abnormal movements.
• Pain with motion or in response to touch: The patient will be asked to move in specific ways. If pressure applied to the lower back causes pain, there may be a degenerated disc.
• Nerve function: The physician taps different areas with a reflex hammer. Poor or no reaction could indicate a compressed nerve root. Hot and cold stimuli may be used to see how well the nerves react to temperature changes.

Other diagnostic tests:

• Imaging scans, such as CT or MRI, to gather information about the state of the spinal nerves, the discs, and how they are aligned.
• A discogram, which involves injecting a dye into the soft center of the disc, or several discs. The aim is to see whether the disc is painful. The dye shows up on a CT scanor X-ray. Discogram usage may be controversial, however, because herniated discs do not always cause symptoms.