The vertebrae are the bony building blocks of the spine. Between each of the largest parts (bodies) of the vertebrae are the discs. Ligaments are situated around the spine and discs.
The spine has seven vertebrae in the neck (cervical vertebrae), 12 vertebrae in the mid-back (thoracic vertebrae), and five vertebrae in the low back (lumbar vertebrae). In addition, in the mid-buttock, beneath the fifth lumbar vertebra, is the sacrum, followed by the tailbone (coccyx).
The bony spine is designed so that vertebrae "stacked" together can provide a movable support structure while also protecting the spinal cord (nervous tissue that extends down the spinal column from the brain) from injury.
Each vertebra has a spinous process, which is a bony prominence behind the spinal cord that shields the cord's nerve tissue. The vertebrae also have a strong bony "body" in front of the spinal cord to provide a platform suitable for weight-bearing.
The discs are pads that serve as "cushions" between the vertebral bodies that serve to minimize the impact of movement on the spinal column. Each disc is designed like a jelly donut with a central softer component (nucleus pulposus).
Ligaments are strong fibrous soft tissues that firmly attach bones to bones. Ligaments attach each of the vertebrae and surround each of the discs. When ligaments are injured as the disc degenerates, localized pain in the area affected can result.
As described above, each disc of the spine is designed much like a jelly donut. As the disc degenerates from age or injury, the softer central portion can rupture (herniate) through the surrounding outer ring (annulus fibrosus). This abnormal rupture of the central portion of the disc is referred to as a disc herniation.
The most common location for a herniated disc to occur is in the disc at the level between the fourth and fifth lumber vertebrae in the low back. This area is constantly absorbing the impact of bearing the weight of the upper body.
This is especially important when we are standing or sitting. The lower back is also critically involved in our body's movements throughout the day, as we twist the torso in rotating side to side and as we hinge the back in flexion and extension while bending or lifting.
The symptoms of a herniated disc depend on the exact level of the spine where the disc herniation occurs and whether or not nerve tissue is being irritated. A disc herniation may not cause any symptoms. However, disc herniation can cause local pain at the level of the spine affected.
If the disc herniation is large enough, the disc tissue can press on the adjacent spinal nerves that exit the spine at the level of the disc herniation. This can cause shooting pain in the distribution of that nerve and usually occurs on one side of the body.
For example, a disc herniation at the level between the fourth and fifth lumbar vertebrae of the low back can cause a shooting pain down the buttock into the back of the thigh and down the leg. Sometimes this is associated with numbness and tingling in the leg. The pain often is worsened upon standing and decreases with lying down.
If the disc herniation is extremely large, it can press on spinal nerves on both sides of the body. This can result in severe pain down both lower extremities. There can be marked weakness of the lower extremities and even incontinence of bowel and bladder. This is medically referred to ascauda equina syndrome.
As mentioned in the beginning of this article, slipped disk (and any other back problem) is an outcome of improper habits of bending, along with this any accident that might have caused direct or indirect pressure on the spinal cords, improper lifting, frequent and improper turning and twisting of back causing high pressure and strain on the spines etc. are the main causes of slipped disk problem.
Factors that lead to a slipped disk include aging with associated degeneration and loss of elasticity of the disks and supporting structures; injury from improper lifting, especially if accompanied by twisting or turning; and excessive strain forces associated with physical activities. Sudden forceful acute trauma is an uncommon cause of a slipped disk.
Occasionally, disc herniation is incidentally detected when a test such as an MRI is performed for other reasons. If no symptoms are present, no particular treatment is necessary.
Depending on the severity of symptoms, treatments for a herniated disc include physical therapy, muscle relaxant medications, pain medications, antiinflammation medications, local injection of cortisone (epidural injections), and surgical operations.
In any case, all people with a disc herniation should rest and avoid reinjuring the disc. Sometimes, even people with relatively severe pain early on can respond to conservative measures without the need for surgical intervention.
There are now a variety of surgical approaches to treat disc herniation. Each type of operation is customized to the individual situation and depends a great deal on the condition of the spine around the disc affected.
Surgical options include microdiscectomy using small surgical instruments and open surgical repair (either from a posterior or anterior approach). Urgent operation can be necessary when cauda equine syndrome is present (described above).