The spinal canal is the cavity enclosing the spinal cord at the heart of the spine. It can be the site of lesions of various kinds, causing spinal cord compression causing pain, motor and sensory disorders.

The medullary canal, also called the medullary cavity, is the cavity in the spine containing the spinal cord.

As a reminder, the spinal cord, or spinal cord, is part of the central nervous system. An extension of the brain, this cord of about forty centimeters allows the transmission of information between the brain and the body, via the spinal nerves which emerge from it through the junction holes.

The medullary canal encloses and protects the spinal cord.

Spinal cord compression

We talk about spinal cord compression when the spinal cord and the nerves that separate from it are compressed by an injury. This compression then causes pain in the back, irradiation and in the most serious cases of motor, sensory and sphincter disorders.

The lesion causing the compression can be located outside the spinal cord (extramedullary lesion) or inside (intramedullary lesion) and be, depending on its nature, acute or chronic. It can be:

• a herniated disc 
• a subdural or epidural hematoma following a trauma having led to a ligament or bone injury, a lumbar puncture, the taking of anticoagulant
• a fracture, a vertebral compression with bone fragments, a vertebral dislocation or subluxation
• a tumor (especially metastatic extramedullary tumor)
• a meningioma, a neuroma
• an abscess
• bone compression due to osteoarthritis
• an arteriovenous malformation
• cervicarthrosis myelopathy

Cauda Equina Syndrome

The area of ​​the spinal cord located at the level of the last lumbar vertebrae and the sacrum, and from which emerge numerous nerve roots connected to the lower limbs and the sphincters, is called a ponytail.

When the spinal cord compression sits at the level of this ponytail, most often due to a herniated disc, it can lead to cauda equina syndrome. This is manifested by lower back pain, pain in the perineum area and in the lower limbs, loss of feeling, partial paralysis and sphincter disorders. This is a medical emergency. 

The medullary infarction

Rarely, the lesion at the origin of the spinal cord compression slows down the arterial vascularization, then leading to a medullary infarction.

Surgery

Surgery is the standard treatment for spinal cord compression. The intervention, called laminectomy, consists of removing the posterior part of the vertebra (or blade) next to the lesion, then removing it in order to decompress the marrow and its roots. This intervention also makes it possible to analyze the lesion.

In the case of cauda equina syndrome, this decompression surgery must take place quickly in order to avoid serious motor, sensory, sphincter and sexual sequelae.

If the lesion causing the spinal cord compression is a hematoma or an abscess, these will be surgically drained.

Radiotherapy

In case of cancerous tumor, radiotherapy is sometimes combined with surgery.

The clinical examination

Faced with motor, sensory, sphincter or sudden onset back pain, it is important to consult without delay. The practitioner will first perform a clinical examination to guide the diagnosis based on symptoms and palpation of the spine.

MRI

MRI is the gold standard for the spinal cord. It makes it possible to locate the site of the spinal cord compression and to direct towards a first diagnosis as to the nature of the lesion. Depending on the indication for the examination, an injection of Gadolinium may be performed.

CT myelography

When MRI is not possible, CT or CT myelography may be done. This examination consists of injecting an opacifying product into the spinal canal in order to visualize the contours of the spinal cord on x-rays.

Spinal X-ray

If a bone lesion is suspected, X-rays of the spine can be taken in addition to the MRI.

Medullary arteriography

In some cases, an arteriography can be performed to look for a possible vascular lesion. It consists of injecting, under local anesthesia, a contrast product then taking a series of images during the arterial and venous circulation phases of this product.