It can mean removal of a disc protrusion or extrusion which is pressing on a nerve root. Hence it will be used to remove the pressure on the nerve and so decompress the nerve. The procedure in this instance will be the removal of the offending part of the disc by means of Discectomy or Microdiscectomy. The latter describes discectomy performed using a microscope through a 4 – 5 centimetre wound.
Here the professional will be referring to the widening of the doorway (Foramen) by which the nerve leaves the spinal canal (tube) to access the body. Conventional surgery through the posterior approach to the spine will either:
- Undercuttingthe doorway using bone punches
- Medial Facetectomy– removal of part of the roof of the doorway – the medial facet (Medial Facetectomy). Both have limited ability to effectively remove compression in the outer part of the doorway.
Where the spinal canal (tube) is congenitally narrow or the natural tube has become narrowed by the overgrowth of the facet joints, the surgeon may advise means of increasing the volume of the spinal canal. This may be achieved either by:
- Laminectomy where the posterior bony arch (Lamina) is entirely removed at one or more levels in the spine.
- Laminotomy where the posterior bony arch (Lamina) is partially thinned or cut away at one or more levels in the spine.
- Laminoplasty where the posterior bony arch (Lamina) is divided on one side and spread and held apart at one or more levels in the spine.
- Interspinous Space insertion: Here the surgeon will insert a device such as spring between the posterior spines which project backwards from the Laminae. This may be combined with removal of overgrown medial facets and the infolding posterior ligaments as the specific pathology dictates. The insertion of the device:
- restores the natural distance between the spines,
- tightens ligaments, pulling them out of the spinal canal
- may tighten and flatten the posterior disc wall
- increases the volume of the exit doorway for the exiting nerves at that segmental (disc) level