What is a Herniated Disk?

herniated disk


Many people have back pain that keeps on returning. Usually it is hard to say what the exact cause is. But if you have pain that radiates down your leg and into your foot, it may be a sign of a slipped spinal disk, or “herniated disk.”

The spinal disks are located between the spinal vertebrae. They have an elastic casing made of cartilage and a gel-like center (nucleus pulposus). A slipped disk occurs if the spinal disk tissue pushes out, or “herniates,” between the vertebrae. This herniated tissue may put pressure on the spinal nerves and irritate them.

A slipped disk can be very unpleasant. But the good news is that the symptoms usually go away on their own within less than six weeks in most people with this problem. But not everybody who has a slipped disk will have symptoms.


A slipped disk can cause very sudden and severe shooting pain. Slipped disks in the lumbar region are the main cause of sciatica (sciatic nerve pain). Sciatica describes pain that radiates down one leg and into the foot. As well as the typical radiating pain, a slipped disk can also lead to pain in the low back region.

In rare cases, numbness in the buttocks or signs of paralysis may develop in addition to the pain and restricted movement. These symptoms are signs of a more serious problem, like nerve damage. Immediate medical attention is needed if the functioning of the bladder or bowels is affected too. That is called “cauda equina syndrome” (CES), and is a medical emergency.

But a slipped disk doesn’t always lead to noticeable symptoms. This can be seen in studies in which adults who didn’t have back pain were examined using magnetic resonance imaging (MRI). More than 50 out of 100 people who were examined had a bulging disk. In about 20 out of 100 of them, the core of the disk had already broken through several layers of its casing or had even entered the surrounding tissue, but without causing any noticeable symptoms.


In most people, slipped disks are the result of wear and tear. Over the years, the spinal disks lose their elasticity: Fluid leaks out of them and they become brittle and cracked. These changes are a normal part of aging, and already start happening when we are young. But not everyone’s spinal disks age at the same pace. Very rarely, an accident or severe injury might also cause damage to a spinal disk and leave it herniated.

Spinal disks act as shock absorbers between the vertebrae in our spine. If a spinal disk is no longer able to bear the strain, it can result in a slipped disk. The associated pain probably arises when part of the spinal disk pushes against a nerve in the spinal cord.

herniated disc

When herniated disk tissue irritates a nerve root in the region of the lumbar spine, it often causes typical sciatic pain. The nervesthat run through the spinal canal connect to the sciatic nerve at the pelvis. The sciatic nerve then runs down the legs. As well as being painful, an irritated sciatic nerve can also cause pins and needles and numbness.

spinal and sciatic nerves

Doctors categorize slipped disks by severity:

  • Prolapse: The disk bulges out between the vertebrae, but its outermost layer is still intact.
  • Extrusion: There is a tear in the outermost layer of the spinal disk, causing spinal disk tissue to spill out. But the tissue that has come out is still connected to the disk.
  • Sequestration: Spinal disk tissue has entered the spinal canal and is no longer directly attached to the disk.

These categories reveal little about what symptoms occur or how severe they might be. But knowing what type of slipped disk someone has is important for the choice of treatment and understanding how the condition might go on to develop.


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