What is an intervertebral disc?
Intervertebral discs are cartilaginous shock absorbers between each bony spine vertebrae. These lumbar discs between the vertebrae allow our spinal columns to flex and extend, as well as to bend from side-to-side. The periphery of the disc is composed of a tough, fibrous layer called the annulus fibrosis. The center is made of a gelatinous substance called the nucleus pulposus. Intervertebral discs are made of cartilage, and cartilage, in turn, is composed of approximately 80% water by weight. As we age, this water content decreases naturally. This loss of water content is accompanied by a loss of disc height and loss of spinal flexibility and strength. The outer annulus fibrosus may develop a small tear through which the inner material herniates.
Disc herniation occurs when a part of the gelatinous nucleus pulposus protrudes through the border of the outer fibrous layer into the spinal canal, thereby creating pressure on the spinal cord and/or nerves. Lumbar disc herniation occurs in the lower back and will protrude into the spinal canal where they can create pressure on nerves that are responsible for pain, sensation, and strength of the lower extremities as well as bowel and bladder function. Common terms describing the movement of disc material out of the disc resulting in compression of a nerve include disc bulge, protrusion, herniation, or extrusion. It is worth noting that the size of the disc herniation does not necessarily correlate with the presence or severity of symptoms.
What can a disc herniation cause?
A disc herniation may present with lower back pain that evolves into shooting pain into either one or both legs. Pain from a herniated disc may be accompanied by either numbness and/or weakness. In rare instances, patients may develop loss of bowel or bladder control. (If you experience weakness extending into both legs, as well as bowel/bladder dysfunction, you could have a serious problem and should seek immediate medical attention).
How do we diagnose a Lumbar disc herniation?
A herniated lumbar disc is typically diagnosed by taking a thorough patient history and physical examination. The pattern of pain, numbness, or weakness usually correlates with the specific nerve that is being compressed (i.e. compression of the L4 or L5 nerve may result in ankle weakness or a foot drop). X-rays of the lumbar spine may show some evidence of disc degeneration. An MRI scan is the study of choice for visualizing the soft tissue structures of the spine including the lumbar discs and the nerves themselves.
An MRI scan is typically reserved for leg pain that persists beyond 6 weeks, while weakness in the leg may require an MRI sooner. It is important to understand that most asymptomatic individuals over the age of 30 will have degenerative changes on an MRI. More often than not, these degenerative changes are age appropriate and clinically irrelevant.
How do we treat a Lumbar disc herniation?
Conservative treatment of disc herniation is usually effective 95% of the time. Bedrest and over-the-counter pain relievers may be all that is needed. The addition of muscle relaxers, anti-inflammatory medications and oral steroids including Prednisone may also be used as first-line treatment. Physical activity should be slow and controlled so that symptoms do not recur. Taking short walks and avoiding sitting for long periods of time is advisable. Physical Therapy may also be prescribed. If conservative treatment fails, epidural steroid injections may lessen nerve irritation and may allow better participation in physical therapy. These steroid injections may be administered on an outpatient basis and may be repeated up to 3 times over 6 to 12 months. In the 5% of patients for whom conservative treatments are not effective, surgery, including lumbar discectomy, may be required.
The most common surgery is called a Microdiscectomy. The procedure is performed under general anesthesia. Patients are discharged the same day of surgery. At Connecticut Neck and Back Specialists, minimally invasive techniques are used to limit the size of the surgical incision in order to minimize the manipulation and disruption of surrounding healthy muscle tissue. When this type of surgery is performed on an outpatient basis, our patients typically return to work within 2 to 6 weeks. Surgical risks include: infection (1%); recurrence of a second disc herniation (10%); spinal fluid leak (5%); scar tissue formation around the exiting nerve resulting in chronic nerve pain (2%); and progressive disc degeneration resulting in back pain that mine requires a subsequent spinal fusion.
When a lumbar discectomy is performed, the nerve that was compressed by the disc herniation is completely freed from all surrounding compression. The rate and extent of nerve recovery are dependent on many factors including the severity of compression, the duration of the compression, the age of the patient, and associated medical conditions including the existence of underlying diabetes, significant smoking history, or a history of significant alcohol consumption.