Tunnel formed the juxtaposition of the empty part of the vertebrae, the spinal canal contains the spinal cord and the nerves. Sometimes it shrinks, causing compression of neurological structures.

The spine, or spine, is made up of a stack of 33 vertebrae: 7 cervical vertebrae, 12 dorsal (or thoracic) vertebrae, 5 lumbar vertebrae, the sacrum made up of 5 fused vertebrae and finally the coccyx made up of 4 vertebrae. The vertebrae are connected by a vertebral disc.

Each vertebra has in its rear part an arch, or orifice. Juxtaposed on top of each other, these vertebral arches form a tunnel: it is the spinal canal, also called the spinal canal, which contains the spinal cord and nerves at its center.

The spinal cord extends from the first cervical vertebra to the second lumbar vertebra. It ends at the level of the second lumbar vertebra with the dural sac which contains the motor and sensory nerve roots of the legs and the bladder and rectal sphincters. This area is called the ponytail.

The spinal canal supports and protects the spinal cord. Within this tunnel formed by the spinal canal, the spinal cord is protected by different meninges: the dura mater, the arachnoid and the pia mater.

Narrow lumbar canal or lumbar canal stenosis

In some people, due to natural wear and tear (osteoarthritis), there is a narrowing of the diameter of the spinal canal at the level of the lumbar vertebrae, that is, in the lower back, above the sacrum. Like all the joints of the human body, the joints of the vertebrae are in fact subject to osteoarthritis which can lead to their deformation with a thickening of the joint capsule to the detriment of the canal. The lumbar canal, normally triangular in shape, will then take a narrowed T-shape, or even become a simple slit. We then speak of narrow lumbar canal, lumbar canal narrowed in still stenosis of the degenerative lumbar canal. The stenosis can only affect the lumbar vertebrae L4 / L5, where the canal is already, at the base, narrower, or in the event of extensive stenosis, other vertebral floors (L3 / L4, L2 / L3 or even L1 / L2) .

This stenosis causes compression of the nerves in the spinal canal resulting in pain often described as a “burn” in the lower back, with irradiation in the buttocks and legs (neurogenic claudication).

These pains have the particularity of worsening with walking or after prolonged standing. It calms down when at rest, sometimes giving way to numbness or ants (paresthesia).

Sometimes this lumbar canal is narrow from birth. This is called a constitutional narrow lumbar canal.

Cauda equina syndrome

The cauda equina syndrome refers to a set of disorders occurring during the compression of the nerve roots located in the lower back, at this area called the cauda equina. The motor and sensory nerve roots of the legs and the bladder and rectal sphincters being compressed, pain, sensory, motor and genitosphincteric disorders then appear.

Lumbar canal stenosis

The first-line treatment is medication and conservative: analgesics, anti-inflammatory drugs, rehabilitation, even corset or infiltration.

In the event of drug treatment failure, and when the pain becomes too disabling on a daily basis or the lumbar canal stenosis leads to paralyzing sciatica, with foot paralysis or urinary disorders, surgery will be offered. A laminectomy or spinal cord release will then be performed, an operation consisting in removing a vertebral lamina (posterior part of the vertebral) in order to free the spinal cord compressed by the stenosis. One or more levels can be operated.

Cauda equina syndrome

Cauda Equina Syndrome is a medical emergency requiring prompt treatment to avoid serious sequelae. Corticosteroid therapy may be offered to relieve pain before neurosurgery. This aims to decompress the nerve root, either by removal of the mass which compresses it (a herniated disc most often, more rarely a tumor), or by laminectomy.

To diagnose spinal stenosis, cross-sections of the spine are made using a CT scan or MRI. The images will show a thickened vertebral bone at the expense of the spinal canal.

A clinical examination makes it possible to make a first diagnosis of cauda equina syndrome, confirmed by an MRI performed urgently.