- Intervertebral Discs
- Bulging vs. Herniated Disc
What is an intervertebral disc?
An intervertebral disc is a cushion of fibrocartilage-containing tissue between two successive vertebrae in the vertebral column. Along with the vertebrae, a disc acts as a fibrous joint that allows some degree of movement to the vertebral column. Discs also act as shock absorbers and prevent the vertebrae from sliding against each other.
An intervertebral disc consists of three distinct components:
- Central nucleus pulposus: Provides flexibility and strength to the spine.
- Peripheral annulus fibrosus: Allow effective resistance of multidirectional movements.
- Vertebral end plates: Two end plates cover the superior and inferior aspects of the disc, permit diffusion, and provide the main source of nutrition for the disc.
Intervertebral disc diseases are commonly characterized by degeneration of one or more discs, causing pain in the back or neck and more frequently in the legs and arms. Two common types of disc diseases are bulging disc and herniated disc.
What is the difference between a bulging disc and a herniated disc?
A bulging disc occurs when the nucleus breaks through the annulus. This means that the disc protrudes outward, into the spinal canal, and can compress a nerve root. Bulging discs are considered to be “contained,” meaning that the disc is intact and has not broken open.
A herniated disc occurs when tears or ruptures in the outside of the annulus allow some soft material of the nucleus pulposus to exit the disc. The nucleus softens and spurts out through a tear in the annulus, meaning it is “non-contained.” It can extrude into the spinal canal, foramen, on either side of the disc or, in some rare cases, in multiple places (called multifocal extruded discs). This can compress a nerve root or the spinal cord. Typically, a disc that herniates is in the final stages of degeneration.
What causes a bulging disc vs. herniated disc?
The most common cause of both bulging discs and herniated discs is age-related wear and tear, also called disc degeneration. With age, the amount of water in the vertebral discs decreases, making them less flexible and more prone to tearing. Other causes include the following:
- Repetitive strain on the neck or back
- Lifting heavy objects
- Poor posture
- Injury or trauma to the spine
- Twisting, turning, or lifting
- Injury or trauma
What are symptoms of a bulging disc vs. herniated disc?
Generally, a bulging disc does not protrude far enough into the spinal canal to pressure or aggravate the surrounding nerves. Acute pain and dysfunction are more common with a herniated disc.
If present, symptoms may include:
What are complications of a bulging disc vs. herniated disc?
In susceptible individuals, a bulging disc could take up too much spinal canal space and cause stenosis. Stenosis can lead to symptoms such as numbness or weakness in one or both of the legs and pain radiating into the legs. Other severe but rare complications, such as loss of normal bowel or bladder function, suggest severe nerve compression and the need for immediate surgical evaluation.
An untreated, severe herniated disc can cause permanent nerve damage. Another long-term complication is saddle anesthesia, which causes a loss of sensation in the inner thighs, back of the legs, and around the rectum.
What are treatment options for a bulging disc vs. herniated disc?
If a bulging or herniated disc has been diagnosed, your doctor is likely to start with conservative treatments such as rest, medication, or physical therapy to help manage symptoms.
Inflammation is the primary symptom of both herniated and bulging discs. After inflammation has been treated and spinal alignment has improved, surgery is often not required.
In severe cases in which pain or dysfunction persists, surgery may be suggested to provide a long-term solution. The most common surgical treatment for a bulging or herniated disc is a discectomy, in which the surgeon decompresses the disc.
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Sahrakar K. Lumbar Disc Disease. Medscape. https://emedicine.medscape.com/article/249113-overview
Baldwin JF. Lumbar (Intervertebral) Disc Disorder Management in the ED. Medscape. https://emedicine.medscape.com/article/827016-overview