A herniated (or slipped) disc is expulsion in the spinal channel of a part of the intervertebral disc. This one being normally located in the space between two vertebras, which he separates.

A hernia occurs in 87 % cases at the level of the last lumbar vertebras: most often between vertebras L4 and L5 (4th and the 5th lumbar vertebra) as a consequence of a wrong movement or of a traumatism. This hernia can draw away a compression of roots at this level: bed of sciatic nerves.

Joint between 2 vertebras

Lower view of a normal disc

Lower view of a disc hernia

Pain felt by the patient cannot however explain only by a mechanical phenomenon.

Other notably chemical phenomena can intervene and there are many hernias of significant volume which are asymptomatic.

These hernias as a protrusion, can lead to a compression of the nervous roots located in regard to the disc.

According to the level of the herniated disc, clinical expression can be a lumbar pain and/or a radicular pain (cruralgia, sciatic nerve).

• In an axial plan:
  • Median
  • lateral Posterior or Para median
  • Foraminal
  • Extra foraminal

• In sagittal plan hernias are described:
  • Ascending
  • Descending

• Hernia can be:
  • Excluded (in relation to the posterior longitudinal ligament)
  • Extruded (by definition)
  • Protrude (incomplete form of herniated disc)
  • Protrue (forme incomplète de hernie discale)

• It is possible that a damaged disc is dehydrated. It appears black to imagery.
  This dehydration of the disc produces an intervertebral packing which can be painful, by crushing of nerves passing between two vertebras