What is a Herniated Disc?
The spinal column is made of many spinal bones (vertebrae) stacked on top of each other. The front part of these bones are connected to each other by intervertebral discs. These discs serve as a flexible cushion and allow for a large range of motion in the spine. The outer portion of these discs is a firm ring of tissue, called the annulus fibrosus (disc wall). Within the center of these discs is a jelly-like substance called the nucleus pulposus.
The disc wall is normally made of circular fibers that contain the jelly-like substance (nucleus) on the inside. As we age, the fibers of the disc wall may lose flexibility and even tear. If the disc wall weakens and tears, disc material from the inside may “herniate” outward and press on nerves in the spinal canal. This may also be referred to as a “herniated nucleus pulposus,” “extruded disc,” or “sequestered disc.”
Often, a disc may “bulge” may occur without a tear in the disc wall. This weakening in the disc wall occurs quite commonly, and does not necessarily lead to a “herniated” disc. A bulging disc rarely, if ever, causes problems, and surgery should not be recommended for this.
Many people will have a herniated disc without knowing it. MRI studies performed on volunteers without pain or symptoms have shown that a large number of people have one or more herniated discs. A herniated disc is not necessarily painful, and the majority of these will not cause problems. Because of this, the most important part of the diagnosis is a proper evaluation by a specialist.
- History: Your medical provider should appreciate that your medical history may contribute to your symptoms, which may or may not be related to your symptoms. It is also important to understand the timeframe for your symptoms, and what makes the symptoms worse or better. Your provider will also learn all previous treatments you have had, and if they have provided any relief.
- Physical Examination: In addition to a good medical history, a thorough physical examination is the most important part of the diagnosis for any spine-related problem. During the physical examination, your provider may try to reproduce your symptoms, and will assess any damage the herniated disc may have caused.
- X-rays: X-rays are often the first step for imaging. Even if other images have been taken, x-rays provide unique information that is not available from other studies.
- MRI: An MRI scanner uses a magnetic field and radio waves that are not harmful to visualize the body in 3D. In most circumstances, it is the best way to see the soft tissues of the body, including nerves, intervertebral discs, and other parts of the spine other than the bones.
- CT: A CT scan uses many x-rays to produce a 3D image of the body. It is often the best way to visualize the spinal bones or bone spurs.
- Injections: Nerve blocks or spinal injections may be used to help diagnose the cause of a patient’s symptoms. In addition to providing relief, they also provide useful information for your provider to pinpoint the cause of symptoms. If you have an injection, it is important to document how the injection affected your symptoms.
Unlike other tissues in the body, intervertebral discs do not have a significant blood supply and do not heal on their own. However, the body will often absorb disc material on its own over time, and doesn’t always require an operation. When the symptoms are dangerous (such as in weakness) or do not respond to non-surgical treatments, a “discectomy” may be recommended. For more information, see Lumbar Microdiscectomy.
A herniated disc may also be referred to as a “slipped disc”. Although this is a common term used to describe a herniated disc, it isn’t really accurate to describe the anatomy of the problem. Vertebrae may become unstable and “slip” on one another, with or without a herniated disc. A true “slip” is also known as a Spondylolisthesis, which may happen with or without a herniated disc.
A herniated disc doesn’t cause pain on its own. However, the disc material may press on spinal nerves or even the spinal cord. This may lead to pain, numbness or weakness in the legs or arms. Pain in the arms or legs is also known as “radicular pain” or “radiculopathy”.
In the most severe cases, it may lead to difficulty with bowel and bladder control in the lumbar spine, or with balance and fine motor skills in the cervical spine. If any of these symptoms occur, you should seek medical attention immediately.