THE LUMBAR SPINE
The lumbar spine is the portion of your spine most commonly referred to as your “low back”.
The lumbar spine is made up of the lowest five vertebrae (bones) and the intervening discs (shock absorbers). The vertebrae are the structural components or “building blocks” of the spine. The lumbar vertebrae tend to be much larger than vertebrae in the other parts of the spine. This is a direct result of the lumbar spine having to support much greater loads than the rest of the spine. Though the spinal cord generally ends above the lumbar spine, there is a “sack” of nerves that continues from the spinal cord through the lumbar spine. This nerve sack runs through a large central opening (spinal canal) formed by the vertebrae. Nerves branching from the nerve sack exit the spinal canal through small holes (foramen) directly adjacent to the discs and travel to your legs.
Like the discs in other parts of your spine, discs in your low back are made up of a tough outer “annulus” and a gelatinous “nucleus”. In many ways the structure of a disc may resemble the structure of a “jelly roll”. The nucleus is the well-hydrated, jelly-like, inner portion of the disc that does the majority of the shock absorbing and is contained by the surrounding annulus (the bread portion of the jelly roll). As you age, the nucleus tends to lose water and the annulus may develop cracks. This process, as we will see, may cause problems as one gets older.
As you grow older the discs in your low back slowly begin to wear out. This is typically a slow, gradual process, which begins at a young age and progresses throughout your lifetime. It is important to understand that this process is not a disease or a disorder, but should be thought of as a “function of use” much like shock absorbers on a car become less shock absorbent as more miles are put on the car. Though this process occurs in everybody, it occurs at different rates in different people. Perhaps the most important factor influencing the rate of disc degeneration is genetics. However, other factors, such as smoking history, trauma, work history and exposure to repetitive vibrational stresses (driving a truck, operating a jackhammer), may also play a significant role in accelerating this process.
A common cause of low back and leg pain is a herniated disc. A herniation occurs when the tough outer annulus of the disc breaks or cracks and the jelly-like nucleus from the inside of the disc leaks out, placing pressure on the nerve sack or on individual nerve roots. Also, the nucleus contains a chemical that can irritate the surrounding nerves causing inflammation and pain.
HOW DO DISCS HERNIATE?
Most lumbar disc herniations occur as a result of an awkward movement or a sudden stress such as a twisting motion while lifting. However, disc herniations may also occur gradually, over weeks or even months.
Risk factors that may contribute to the likelihood of a disc herniation may include:
Aging. As we age, discs gradually lose fluid. The outer annulus may develop cracks within it, which may allow the nucleus to seep out and compress an adjacent nerve.
Lifestyle choices. Lack of regular aerobic exercise, becoming overweight, and tobacco use substantially contribute to poor disc health.
Exposure to repetitive vibrational stresses in the workplace or otherwise may weaken discs and predispose to disc herniation. Poor posture, incorrect and/or repetitive lifting or twisting can place additional stress on the lumbar spine.
TREATMENT FOR LUMBAR DISC HERNIATION
Fortunately, most cases of lumbar disc herniations do not require surgery. A frequent question asked by patients is “When I get better, what happens to the herniated part of the disc? Does it go back into the disc space?” The answer is no. Remember, the analogy of a herniated disc to a jellyroll with a leak in it. Imagine how difficult it would be to take the jelly that has leaked out of the jellyroll and put it back through the crack that it came through. Likewise, it is virtually impossible for the herniated portion of the nucleus to find its way back through a tiny crack in the annulus to the inner part of the disc, where it is “supposed to be”.
So what happens to the herniated portion of nucleus in the large percentage of cases that get better? Studies have indicated that a small percentage of the time there may actually be some dissolution of the disc by various enzymes and factors released by the body in the inflammatory reaction that is instigated when the disc rupture occurs. Probably, more frequently, the compressed nerve simply gets “used” to its new environment and finds a way to function though the herniated portion of the disc remains.
Unfortunately, it is not possible to predict which cases of disc herniation will improve and which will not. Dr Ibrahim feels that the vast majority of lumbar disc herniations do not constitute any significant danger to the patient. Thus, conservative care is nearly always an option. Conservative options frequently prescribed may include the following:
Pain medications such as anti-inflammatories to reduce swelling and pain, muscle relaxants to calm muscular spasm, and occasionally painkillers to alleviate acute pain.
Heat/cold therapy, especially during the “acute” phase of injury (the first several days).
Gentle physical therapy such as massage, stretching and pelvic traction.
Epidural injections. For individuals with severe pain, a localized dose of cortisone in the vicinity of the disc herniation will calm the nerve and help symptoms to settle down. It is important to realize that this does not “cure” the disc herniation, but simply allows the patient some degree of comfort while his/her body attempts to “take care of” the problem. Epidural injections are typically most effective when given within a month of onset of symptoms.
Probably the best predictor of whether or not symptoms of a disc herniation will improve is the duration of time that the symptoms have been present. It makes sense that if an individual has been suffering with pain for several months, they are far less likely to have resolution of their symptoms with conservative care than an individual who has had pain only for a few days.
If the patient’s pain is intractable and/or conservative care has not been effective or if the patient has had severe symptoms for a considerable period of time or if a neurologic deficit is developing (weakness in the leg muscles), then Dr Ibrahim may recommend surgical intervention to treat the disc herniation.