Lumbar Herniated Disc
Description
In between each of the five lumbar vertebral bodies (bones of the lower back), lies a disc. The disc connects each of the vertebral bodies, providing flexibility and distributing equally loads applied to the
spinal column. The disc is composed of collagen fibers providing tensile strength, stiffness, and resistance to compression. The outer rubber-like band of the disc (called the annulus fibrosus) encases a jelly-like substance (called the nucleus pulposus). A herniated disc is a fragment of the central portion of the disc (the nucleus), which is pushed through a tear in the outer disc structure (the annulus), into the spinal canal. In the herniated disc's new position, it presses on a spinal nerve producing pain down the accompanying leg in the distribution of the nerve root involved. A herniation may develop suddenly or insidiously over weeks or months. In a normal, healthy disc, the nucleus distributes the load equally throughout the annulus. As the disc undergoes degeneration, either by genetic factors, wear and tear, or specific injury the nucleus loses some of its cushioning ability and transmits the load unequally throughout the annulus. In general, if a disc herniation is responsible for low back pain, the patient will be able to recall the exact time of injury and contributing factors. The most common levels for herniations occur at L4-L5, and L5-S1.
Symptoms
Typically, a herniated disc is preceded by an episode of low back pain or a long history of intermittent episodes of low back pain. Patients describe sharp pain radiating down the leg. This pain may be associated with numbness and tingling. Patients may also complain of burning and stabbing-like sensations. Generally, pain is associated with standing, walking, sitting, sneezing, or coughing. They usually find relief by lying down. Weakness of the leg may be present.
Treatment
Approximately 90% of patients will have their symptoms resolve spontaneously within four to six weeks. While lumbar disc herniations may cause a significant amount of back and leg pain, the majority of patients experience resolution of symptoms regardless of treatment. Rest, anti-inflammatory medication, pain medication, and physical therapy are usually beneficial. If leg pain and weakness persist, epidural steroid injections may be warranted. Recent studies have demonstrated that transforaminal epidural steroid injections prevented surgery in 65% of patients who had already been scheduled to undergo discectomy. Surgery is reserved for those patients who fail to improve with conservative measures. To alleviate nerve pressure and leg pain, surgery involves removal of the herniation fragment compressing the nerve (discectomy). This can be done through a minimally invasive approach using a microscope.
Procedure
Improvements have been made in the tools available to the spinal surgeon for performing discectomy. Microdiscectomy involves using an operating microscope to locate and remove disc material that has ruptured into the spinal canal. This procedure is performed through a one-inch incision. Approximately 90-95 % of all patients will obtain significant relief of their symptoms after surgery. The indications for this procedure are similar to those for traditional discectomy.
