A herniated disc occurs when the inner core of a spinal disc leaks out through the disc’s weakened outer layers, sometimes causing pain and other symptoms that radiate down a nerve.
The following is a clear, visual explanation of this process using still shots from our Telly Award-winning animated video: Herniated Disc Video.
Why do discs herniate?
Each vertebra in your spine is separated from the next by a spinal disc. These discs allow for flexibility and movement of the spine, absorbing shock when you move.
Degeneration over time or a sudden trauma may cause weak spots to form in the outer layers—the annulus fibrosus—of a spinal disc. When this occurs, the soft, gelatinous center of the disc—the nucleus pulposus—can leak out.
When this disc material herniates, it can interact with nearby nerves exiting the spine—either through irritation caused by inflammatory proteins in the disc's core or through disc matter directly compressing the nerve.
This causes symptoms to radiate down the path of the nerve being affected.
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Where herniations are likely to occur
Because it's at the bottom of the spine, in the lower back, the lumbar spine carries more weight and endures more wear and tear than the rest of the spine. That's why this portion of the spine is particularly susceptible to injuries like disc herniation.
If a herniated disc has affected a nerve in the lumbar spine, it can cause pain to radiate down the back of your leg. It can also cause neurological symptoms like tingling or numbness. These symptoms are often referred to as sciatica.
Discs can also sometimes herniate in cervical spine, found in the neck. Cervical herniated discs are less common than lumbar herniated discs, and are most frequent among people between the ages of 30 and 50.
When a disc in the cervical spine herniates, it may cause pain and symptoms into the shoulder and down the arm.
The least common area of the spine to be affected by disc herniations is the thoracic spine (the upper back). However they can still occur here occasionally. Thoracic disc herniations can cause symptoms in the upper back and sometimes chest.
Keep in mind that the relationship between herniated discs and the symptoms they cause is a tricky one. Some people can experience severe pain from a mild herniation, while others can have a severe herniation that causes no symptoms at all.
If you're diagnosed with a herniated disc, rest assured that there are many treatment options to address pain and other symptoms.