What is meant by a slipped disc?

The disc may not only change shape and 'slip' outwards, it can also tear. Then the jelly-like contents can escape into the spinal canal.

A slipped is the consequence of damage to an intervertebral disc. And damage to the disc comes from age-related wear and tear which can be accelerated by overexertion or abnormal postures of the spine. If a part of the disc, because it is damaged, bulges in the direction of the spinal canal or the disc even ruptures, then its content escapes into the spinal canal. In both cases this is called a 'slipped disc'. The disc protrudes forwards or backwards &ndash, usually in the direction of the spinal canal towards where the spinal nerves run.

Anatomy of the intervertebral disc.

The disc consists of a viscous nucleus and a firm fibrous ring. The most frequent point of rupture is where the spinal cord and spinal nerves run.

Discs are the spine's shock absorbers. They consist of a firm outer layer which is filled with a jelly-like viscous contents and a firm nucleus. The outer layer is like an onion and consists of several fibrous layers. Therefore it is called a ;'fibrous ring';. An anterior and posterior longitudinal ligament borders on the fibrous ring. The longitudinal ligament separates the intervertebral disc from the spinal canal.

The older we become the more discs continue to lose fluid forfeiting elasticity and flexibility – similar to a sponge drying out in the sun. A moist sponge is flexible and always returns to its original shape. A dry sponge is brittle, non-elastic and when pressed retains its shape.

Therefore discs too when they have less water content and are pressed more forcefully together – are no longer able to return to their original shape. Overall they lose height.

From damage to intervertebral discs to a slipped disc.

If the disc dries out slowly the fibrous ring develops fissures. These develop primarily in the area adjoining the spinal canal through which the nerve paths run in the vertebral column. Parts of the soft, jelly-like contents of the disc may escape into these fissures of the fibrous ring. The disc slowly changes shape and bulges in the direction of the spinal canal. This status is the precursor to a slipped disc.

If the external skin ruptures completely because of the resultant pressure, a hole develops in the fibrous ring. The the jelly-like contents and even possibly the firm nucleus escape into the spinal canal. This can cause the nerves in the spinal canal to become compressed. In this case patients complain about symptoms of paralysis. Then a doctor must be consulted immediately.

Different types of slipped discs.

Different forms of slipped disc can be distinguished:

• Bulging disc (med.: Intervertebral disc protrusion): The disc bulges but the fibrous ring remains intact
• Slipped disc (med.: Prolapsed disc): Disc tissue escapes through the fibrous ring
• separated slipped disc (med.: sequestered prolapsed disc): Disc tissue breaks through the longitudinal ligament and escapes through the fibrous ring into the spinal canal
• separated slipped disc with release of a fragment (med.: subligamentous prolapsed disc with sequestration): The disc ruptures the posterior longitudinal ligament. Fragments of tissue break away and escape into the spinal canal.

The most frequent type of slipped disc.

Slipped discs are diagnosed most frequently – around 80-85% in the lumbar spine region. This is where the spine is put under the most stress. The cervical spine therefore which only has to bear 5 to 6 kilos accounts for only 10-15% of all slipped discs. The least common type of slipped discs are those in the thoracic spine. Here, the thoracic spine is stabilised by the rib cage and barely moves.