Disc herniations are normally a further development of a previously existing disc “protrusion”, a condition in which the outermost layers of the annulus fibrosus are still intact, but can bulge when the disc is under pressure. In contrast to a herniation, none of the nucleus pulposus escapes beyond the outer layers.
Factors that lead to slipped disc include aging with associated degeneration and loss of elasticity of the discs and supporting structures; Poor posture combined with the habitual use of incorrect body mechanics, hard physical labour (delivery), improper lifting, especially if accompanied by twisting or turning; excessive strain, and sudden forceful trauma. A herniation may develop suddenly or gradually over weeks or months.
Herniated discs can occur in any part of the spine. Herniated discs are more common in the lower back especially at the L4-L5 and L5-S1 levels (lumbar disc herniation). This is because the lumbar spine carries most of the body’s weight. The second most common area is neck (cervical disc herniation). The area in which you experience pain depends on what part of the spine is affected.
The progression to an actual Herniation varies from slow to sudden onset of symptoms. There are four stages:
- disc protrusion
- prolapsed disc
- disc extrusion
- sequestered disc
Stages 1 and 2 are referred to as incomplete, where 3 and 4 are complete herniations. Pain resulting from herniation may be combined with a radiculopathy, which means neurological deficit. The deficit may include sensory changes (i.e. tingling, numbness) and/or motor changes (i.e. weakness, reflex loss). These changes are caused by nerve compression created by pressure from interior disc material.
People between the ages of 30 and 50 appear to be vulnerable because the elasticity and water content of the nucleus decreases with age. But of late it is seen that even the people around age group 20 – 30 are also getting affected with slip disc, because of their life style, stress and diet habits.