The Surgical treatment of Lumbar Spinal Stenosis
Following your recent MRI scan and consultation with Mr Paremain you have been diagnosed with a narrowing of your lumbar spinal canal (stenosis). This is usually related to the wear and tear of the spine.
The normal spinal column has a central canal (or passage) through which the spinal cord passes down. To each side of the canal, spinal nerve roots branch out at every level. The spinal cord stops at the top of the lumbar spine (low back) and below that tiny nerve rootlets splay out like a horse’s tail (cauda equina). The spinal cord, nerve roots and cauda equina are surrounded by cerebrospinal fluid (CSF) and are all contained within a membrane, or covering, called the dura mater, rather like the thin layer that covers a boiled egg with the shell removed.
The ligamentum flavum is a tough band of elastic tissue (ligament) that connects the vertebrae (bones of the spine) and provides stability for posture and protection for the dura mater.
The intervertebral disc is a structure between the vertebrae, which acts as both a spacer and a shock absorber. Over time, as disc degeneration (wear and tear) occurs, the disc will lose water and height and, as such, close down the bony passage (foramen) where the nerve root passes through on leaving the spine.
In spinal stenosis, the spinal nerve roots and/or cauda equina become trapped or compressed by the narrowing of these nerve passages, by arthritic joint swelling and bony overgrowths (osteophytes) which grow into the spinal canal and the bunching up (buckling) of the ligamentum flavum, like an elastic band losing tension, or bulging of the intervertebral discs. Rarer cases include cysts or fatty collections or tumours in the spinal canal.
Diagram 1 below is an impression of the MRI scan on the right which demonstrates spinal stenosis of the central spinal canal.