Causes of bulging lumbar discs
The bony spine is designed so that vertebrae "stacked" together can provide a movable support structure while also protecting the spinal cord that extends down the spinal column from the brain. Each vertebrae has a spinous process, which is a bony prominence behind the spinal cord that protects the cord's nerve tissue. The vertebrae also have a strong bony "body" in front of the spinal cord to provide a platform suitable for weight-bearing. The discs are pads that serve as "cushions" between each vertebral body which minimize the impact of movement on the spinal column. Each disc is consists of a central softer component (nucleus pulposus). This softer component can rupture (herniate) through the surrounding outer ring (annulus fibrosus) and irritate adjacent nervous tissue. Ligaments are strong fibrous soft tissues that firmly attach bones to bones. Ligaments are attached to each of the vertebrae and surround each of the discs. Ligament injury can occur as the disc degenerates. Pain, is the result. With aging, the intervertebral disc may lose water and become dried out. As this happens, the disc compresses. This may lead to the deterioration of the tough outer ring allowing the nucleus, or the inside of the ring, to bulge out. This is considered a bulging disc. As the disc continues to degenerate, or with continued stress on the spine, the inner nucleus pulposus may actually rupture out from the annulus. This is considered a ruptured, or herniated, disc. The fragments of disc material can then press on the nerve roots that are located just behind the disc space. This can cause pain, weakness, numbness, or changes in sensation. Most disc herniations happen at the lower lumbar spine, especially at the L4-5 and L5-S1 levels. Lumbar disc disease is due to a change in the structure of the normal disc. Most of the time, disc disease comes as a result of aging and the degeneration that occurs within the disc. Occasionally, severe trauma can cause a normal disc to herniate. Trauma may also cause an already herniated disc to worsen. Most often, discs herniate because of injury or improper lifting, but aging also plays a role. As you get older, your discs dry out and become harder. The tough fibrous outer wall of the disc, or annulus, may weaken, and it may no longer be able to contain the gel-like substance in the center. This material may bulge or push out through a tear in the disc wall, causing pain when it touches a nerve. Genetics, smoking, and a number of occupational and recreational activities may lead to early disc degeneration. Because both the discs and the joints that stack the vertebrae (facet joints) are partly composed of cartilage, these areas undergo wear and tear over time (degenerative changes). The gradual deterioration of the disc between the vertebrae is referred to as degenerative disc disease. About 12 million Americans have degenerative disc disease.
Degeneration of the disc is medically referred to as spondylosis. Spondylosis can be noted on x-ray tests or MRI scanning of the spine as a narrowing of the normal "disc space" between the adjacent vertebrae. Degeneration of the disc tissue makes the disc more susceptible to bulging and herniation. Degeneration of the disc can cause local pain in the affected area. Any level of the spine can be affected by disc degeneration. Degenerative arthritis (osteoarthritis) of the facet joints is also a cause of localized lumbar pain that can be detected with plain x-ray testing. The pain from degenerative disc or joint disease of the spine is usually treated conservatively with intermittent heat, rest, rehabilitative exercises, and medications to relieve pain, muscle spasm, and inflammation. Radiculopathy refers to nerve irritation caused by damage to the disc between the vertebrae. This occurs because of degeneration ("wear and tear") of the outer ring of the disc, or because of traumatic injury, or both. Weakness of the outer ring leads to disc bulging and herniation. As a result, the central softer portion of the disc can rupture through the outer ring of the disc and put pressure on the spinal cord or its nerves as they exit the bony spinal column. When nerves are irritated in the low back from degenerative disc disease, the condition is called lumbar radiculopathy. This presents as "sciatica" pain that shoots down the lower extremity. This condition can be preceded by a localized low back aching. Sciatica pain can follow a "popping" sensation at onset and be accompanied by numbness and tingling. The pain commonly increases with movements at the waist and can increase with coughing or sneezing. In more severe instances, lumbar radiculopathy can be accompanied by incontinence of the bladder and/or bowels. Radiculopathy is suspected when the symptoms described above are noted. The doctor can sometimes detect signs of irritated nerves during the examination. For example, increased radiating pain when the lower extremity is lifted supports the diagnosis of lumbar radiculopathy. Nerve testing (EMG/electromyogram and NCV/nerve conduction velocity) of the lower extremities can be used to detect the nerve irritation. The actual disc herniation can be detected with radiology testing, such as CAT or MRI scanning.
The treatment of radiculopathy ranges from nonsurgical (medical) management to surgery. Medical management of radiculopathy includes patient education of the condition, medications to relieve pain and muscles spasm, cortisone injection around the spinal cord (epidural injection), physical therapy (heat, massage, ultrasound, electrical stimulation), and rest (not strict bed rest, but avoiding re-injury). With unrelenting pain, severe impairment of function, or incontinence (which can indicate spinal cord irritation), surgery may be necessary. The operation performed depends on the overall status of the spine, and the age and health of the patient. Procedures include removal of the herniated disc with laminotomy (a small hole in the bone of the spine surrounding the spinal cord), laminectomy (removal of the bony wall), by needle technique through the skin (percutaneous discectomy), disc- dissolving procedures (chemonucleolysis), and others.
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