Stenosis — What It Means on Your Imaging Report

Quick Answer

Stenosis means narrowing of a body passage or channel — most commonly the spinal canal — and is often a normal part of aging that does not always cause symptoms.

What Is Stenosis?

Stenosis is a medical term that simply means narrowing. It can refer to the narrowing of any tube-like structure in the body, including blood vessels, heart valves, and the spaces in and around the spine. However, when patients encounter the word on an imaging report, it most commonly refers to spinal stenosis — narrowing of the spaces within the spine that the spinal cord and nerves pass through.

The spine has a central canal (the spinal canal) that houses the spinal cord, and smaller openings on each side (called neural foramina) where individual nerve roots exit. Over time, the discs between vertebrae lose water and height, the joints enlarge, and ligaments may thicken. These gradual changes can narrow the available space. The three main types of spinal stenosis radiologists describe are:

• Central canal stenosis — narrowing of the main spinal canal that contains the spinal cord or the bundle of nerve roots called the cauda equina
• Foraminal stenosis — narrowing of the small openings on the sides of the spine where nerve roots exit to reach the arms or legs
• Lateral recess stenosis — narrowing of the area just before the nerve root enters the foramen

Radiologists grade the severity as mild, moderate, or severe based on how much the space has narrowed and whether the nerves or spinal cord appear compressed.

When You Might See This on Your Report

Stenosis is one of the most frequently reported findings on spine imaging:

• MRI of the spine — this is the primary imaging study for evaluating spinal stenosis. MRI provides excellent detail of the soft tissues, including discs, ligaments, nerves, and the spinal cord. Your report may say something like "mild central canal stenosis at L4-L5" or "moderate bilateral foraminal stenosis at C5-C6."
• CT of the spine — CT is particularly good at showing bony changes that contribute to narrowing. It is sometimes used when MRI is not possible or as a complement to MRI before surgery.

Beyond the spine, stenosis may also appear on imaging reports in other contexts:

• CT angiography — may report stenosis of the carotid arteries (narrowing of neck arteries supplying the brain) or coronary arteries
• Echocardiograms — may identify stenosis of heart valves, such as aortic stenosis

However, the vast majority of patients who see "stenosis" on an MRI or CT report are dealing with spinal stenosis, so that is the focus of this guide.

Should I Be Worried?

Some degree of spinal stenosis is extremely common and is a normal part of aging. Studies published in peer-reviewed journals have shown that significant numbers of adults over 50 have evidence of spinal stenosis on MRI — even without any back pain or other symptoms. One large study found that over 80% of people over age 70 have at least mild lumbar stenosis on imaging.

Here are the key factors your doctor will consider:

• Severity on imaging does not always match symptoms. A person with moderate stenosis on MRI may feel perfectly fine, while someone with mild stenosis may have noticeable symptoms if a nerve is being compressed in a specific way. The imaging finding alone does not determine your treatment.
• Mild stenosis is frequently incidental and generally does not require any specific treatment. It is often mentioned in the report because the radiologist describes everything they see.
• Moderate to severe stenosis with corresponding symptoms — such as leg pain, numbness, tingling, or weakness — may benefit from treatment, but even then, many patients improve with non-surgical approaches.
• Symptoms matter more than pictures. Your doctor will correlate what the MRI shows with what you are actually experiencing. A stenosis finding is clinically significant only when it explains your symptoms.

What Should I Do Next?

1. Read the Impression section of your report for the radiologist's summary. They will typically note the location, severity, and whether there is any nerve or spinal cord compression.
2. Discuss the findings with your doctor. They will determine whether the stenosis on imaging matches your symptoms. Many people have stenosis on MRI that requires no action.
3. Ask about conservative treatment first. If your stenosis is causing symptoms, physical therapy, anti-inflammatory medications, and activity modifications are effective first-line treatments for many patients.
4. Follow up if symptoms change. If you develop new numbness, weakness, difficulty walking, or changes in bladder or bowel function, contact your doctor promptly — these may indicate worsening nerve compression.
5. Do not assume you need surgery. Surgery for spinal stenosis is typically reserved for patients with significant, persistent symptoms who have not improved with conservative care. Most patients with stenosis reported on imaging will never need surgical intervention.