The spine is made up of what we call segments or functional units, which are composed of the vertebrae and the intervertebral discs in the anterior part, and the interapophyseal joints or facets in the posterior part. In all people, with age and the passage of time, these structures tend to undergo degenerative changes, i.e., to wear out. This is a fact that we could consider a normal aging of the spine, and many times it will be asymptomatic or with mild symptoms.
This “wear and tear” of the lumbar spine, which as we said appears mainly with age (although there are also other predisposing factors such as heredity, overweight or obesity, or certain jobs that have repeatedly required great effort at the level of the lumbar spine) will sometimes cause what we call narrow lumbar canal or lumbar canal stenosis.
What is a narrow lumbar canal?
We speak of narrow lumbar canal or canal stenosis when the degenerative changes that have appeared at the level of the spine, i.e., the loss of height of the intervertebral discs and arthrosis of the interapophyseal joints (facets), cause a decrease in the diameter of the lumbar canal, through which the spinal nerves pass. In other words, lumbar osteoarthritis causes, very progressively, a hypertrophy or degeneration of the joints of the spine (facets), which become larger, and these narrow the lumbar canal compressing the spinal nerves.
This pathology is not typical of young people, who present other pathologies more typical of their age, such as disc herniation, but generally occurs after the age of 50.
What are the symptoms of a narrow lumbar canal?
In many patients with a narrow lumbar canal, as we understand that it could be part of the “normal” aging of the spine, no symptoms will appear or they will be mild. However, in other patients this progressive narrowing of the canal will cause very disabling symptoms.
The most frequent symptoms are:
- Low back pain.
- Sciatic pain in one or both lower extremities.
- Neurogenic claudication of gait: this is the most characteristic symptom, which means that the patient’s legs “give out” when he/she walks a few meters, causing pain, a feeling of “sluggishness” and tingling, which forces him/her to stop walking. Typically the patient improves fairly quickly when he sits down, and can resume walking a few more meters, until he stops again. This symptom is caused by compression of the spinal nerves in the narrow part of the lumbar canal.
- In more severe and advanced cases, loss of leg strength may occur, even at rest.
How is narrow lumbar canal diagnosed?
The clinical data and symptoms described in the previous section are very characteristic of lumbar canal stenosis. We will try to confirm our diagnostic suspicion with complementary explorations, the most important being lumbar MRI. If canal stenosis is present, it will be clearly seen on magnetic resonance imaging. Other tests that may be useful are spinal X-rays, spinal CT or electromyogram.
What is the treatment for a narrow lumbar canal?
The narrow lumbar canal should only be treated when it is symptomatic and causes claudication of gait. That is to say, we should not treat a patient who only presents low back pain and who has been diagnosed with a narrow lumbar canal in an MRI.
On the other hand, we will treat those patients with pain radiating down the leg or with gait claudication. Apart from anti-inflammatory medication, which has been shown to be of little use in these cases, the first therapeutic option will be epidural infiltration. This is an outpatient procedure in which an anesthesiologist specializing in pain therapy injects anti-inflammatory drugs into the spinal column.
If this treatment is not effective, we will opt for surgical treatment. This treatment is performed, if possible, by means of minimally invasive surgical techniques, which offer excellent clinical results and great satisfaction for the patient in the short and long term. In other cases, open surgery will be chosen, which will be equally effective and satisfactory for the patient. In some patients it will be sufficient to decompress the spinal canal, that is, to free those nerves that are under pressure, and in other cases, apart from decompression, we will have to perform fixation or arthrodesis of the lumbar spine, using titanium screws and rods joined together, and providing bone grafting to achieve correct spinal fusion. Treatment should be individualized for each patient.