Spinal canal stenosis on an MRI means the main central tunnel that carries the spinal cord and nerves has narrowed.
In more detail
- The central canal narrows from a mix of three things. The disc bulges from the front. The facet joints enlarge from behind. And the ligamentum flavum (a ligament along the back of the canal) thickens.
- It is graded mild, moderate or severe, and it is reported level by level.
- In the neck, severe narrowing can press on the spinal cord itself. That is a different and more serious problem than a pinched nerve root, and we look for it on purpose.
What it means for you
The classic symptom in the lower back is neurogenic claudication. That means leg pain and heaviness after you walk a set distance, eased by sitting or leaning forward. See spinal stenosis for how it is treated.
Remember the general rule. Findings like this one are common in people with no pain at all. They get steadily more common with age. A finding on a report is not a diagnosis until someone has matched it to your symptoms and your exam. See understanding your MRI report.
Bring your scan and report in and we will go through it with you. Call us or request an appointment.
How common is it, and what does it predict?
Canal stenosis means narrowing of the central spinal canal. It usually comes from a mix of thickened ligament, enlarged facet joints and disc bulging built up over decades. Reports often give a measurement in millimeters. Those numbers match symptoms only loosely, because the space changes with position. Bending back closes the canal and bending forward opens it. So a scan taken lying still does not show what happens when you walk. In the low back, the telltale symptom is leg heaviness after you walk a set distance, eased by sitting or leaning forward.
Common questions
Does severe stenosis on the report mean surgery?
Not automatically. The decision rests on your symptoms and function, not on the word the radiologist chose.
Mild, Moderate, Severe — What the Grades Mean explains what the grades do and do not tell you.
Why can I walk further pushing a shopping cart?
Leaning forward opens the canal. This shows up so reliably that it is used to make the diagnosis.
Spinal Stenosis goes through it in detail.
What does the millimeter measurement mean?
Less than patients expect. Space changes with position, and the measurement is taken lying down. How far you can walk before symptoms start is a more useful number.
The mechanism is covered in Mild, Moderate, Severe — What the Grades Mean.
Does stenosis always need surgery?
No. Many people manage for years with walking in short bouts and building fitness. Several less invasive options come before surgery.
Spinal Stenosis goes through it in detail.
Why is my walking distance more useful than the scan?
Because the canal changes size with position, and the scan is taken lying still. Distance before symptoms measures the problem under the conditions that really cause it.
Sources
- Katz JN et al. Diagnosis and Management of Lumbar Spinal Stenosis: A Review. JAMA, 2022. PubMed 35503342
- Brinjikji W et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR. American journal of neuroradiology, 2015. PubMed 25430861
- Webb CW et al. Lumbar Spinal Stenosis: Diagnosis and Management. American family physician, 2024. PubMed 38648834
- Fardon DF et al. Lumbar disc nomenclature: version 2.0: Recommendations of the combined task forces of the North American Spine Society, the American Society of Spine Radiology and the American Society of Neuroradiology. The spine journal : official journal of the North American Spine Society, 2014. PubMed 24768732
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