In the lower back, the spine is made up of five lumbar vertebrae. Each of them has an orifice in its center: the lumbar canal, which contains the spinal cord. Under the effect of osteoarthritis, one can observe a narrowing of this lumbar canal. This pathology, called the narrowed lumbar canal, is more and more frequent due to the aging of the population.

The spine, or spine, is made up of 24 vertebrae: 7 cervical vertebrae, 12 dorsal vertebrae and 5 lumbar vertebrae. Each vertebra has an arch in its rear part. Juxtaposed on top of each other, these holes form a tunnel. This is the spinal canal, which contains the spinal cord and nerves at its center. At the level of the 5 lumbar vertebrae, we speak more precisely of the lumbar canal.

The spinal cord ends at the level of the second lumbar vertebra with the dural sac which contains nerve roots. Exiting through orifices located between two vertebrae, these nerve fibers give rise to the nerves controlling the muscles of our legs but also the muscles for the sphincters of the anus, the bladder and the sexual organs. This highly innervated area in the lower back is called the ponytail.

The lumbar canal supports and protects the spinal cord in the lumbar area.

Narrowed lumbar canal or lumbar canal stenosis

Like all joints, those of the vertebrae are prone to osteoarthritis. This can lead to a deformation of the joint with bone growth to the detriment of the lumbar canal, the diameter of which will then be narrowed. This pathology is called narrowed lumbar canal, narrowing of the lumbar canal or stenosis of the lumbar canal.

The stenosis can only affect the L4 / L5 lumbar vertebrae, where the canal is initially narrower, or, in the case of extensive stenosis, other vertebral floors (L3 / L4, L2 / L3 or even L1 / L2).

In 10 to 15% of patients, the stenosis will be asymptomatic. In others, this narrowing of the canal causes compression of the nerve roots, the ponytail and the covering that protects it (the dura), resulting in pain often described as a “burn” in the lower part. from the back with irradiation in the buttocks and legs, generally symmetrically. The pain worsens on walking (and more rapidly on descent due to increased lumbar lordosis resulting in decreased canal volume) or after prolonged standing, and subsides when resting, sometimes giving way to a numbness or ants (paresthesia). This so-called intermittent claudication syndrome is typical of lumbar spinal stenosis.

More rarely, the narrowing of the lumbar canal is the consequence of a deformation of the spine occurring in adult scoliosis or spondylolisthesis (sliding of two vertebrae relative to each other.

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

Cauda equina syndrome

Cauda equina syndrome refers to a group of disorders occurring during compression of the nerve roots of the cauda equina. The motor and sensory nerve roots of the legs and of the bladder and rectal sphincters being compressed, pain, sensory, motor and genitosphincter disorders (problem with urination, incontinence, impotence) then appear.

Narrowed lumbar canal

The first-line treatment for a narrowed lumbar canal is drug and conservative. It aims to relieve pain, in the same way as that of common low back pain, with analgesics and NSAIDs. Corticosteroid infiltrations can be performed in the epidural space. Physiotherapy may be considered. It will focus on muscle reconditioning in lumbar flexion associated with strengthening the abdominal muscles and the pelvic floor.

If drug treatment has failed, surgery may be considered.

Depending on the degree of narrowing of the lumbar canal, sometimes it is enough to remove the damaged part of the bone to release the compression of the nerves. This intervention is called recalibration.

In case of more important stenosis, a laminectomy or medullary release will be performed. It consists of removing a vertebral lamina (posterior part of the vertebral) in order to free the channel of the spinal cord. One or more levels can be operated.

Cauda equina syndrome

Cauda equina syndrome requires very rapid treatment in order to avoid serious sequelae. Corticosteroid therapy may be offered to relieve pain before performing neurosurgical intervention. This aims to decompress the nerve root, either by removal of the mass which compresses them (a herniated disc most often, more rarely a tumor), or by laminectomy.

The diagnosis of the narrowed lumbar canal is initially clinical. An x-ray of the lumbar spine can be used to visualize the narrowing of the canal. To clarify the diagnosis and in particular the degree of stenosis, cross-sections of the spine by CT or MRI are then made. 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, most often confirmed by an MRI performed urgently.