Spinal Stenosis
Narrowing of the spinal canal compresses the nerves inside it. Symptoms often develop gradually and can be mistaken for normal aging.
Also Called: Central canal stenosis, foraminal stenosis, narrowing of the spinal canal, neurogenic claudication (the name for the specific leg-symptom pattern stenosis causes).
What It Is
Stenosis means narrowing. In the spine, it means less room for the spinal cord and nerve roots, usually from a bulging disc, thickened ligament, and enlarged joints crowding the canal. In the lower back it causes pain, heaviness, or cramping in the legs. The symptoms get worse with standing or walking and better with sitting or leaning forward. That pattern helps separate it from leg pain caused by poor circulation.
Causes & Risk Factors
Age-related wear is the main driver: disc bulging, ligament thickening, and joint enlargement. Stenosis is uncommon before middle age and common after it. By age 50 most people show some of these changes on imaging, though only a fraction have symptoms. Some people are born with a narrow canal, so it takes less change to cause symptoms. A slipped vertebra at the same level can narrow the space further.
Symptoms
- In the lower back: pain, cramping, or heaviness in the legs that worsens with walking and improves with sitting
- In the neck: arm symptoms, or in more advanced cases, problems with balance, coordination, and hand function
Diagnosis
The pattern of the symptoms carries most of the diagnosis. Leg pain, cramping, or heaviness that comes on with standing and walking and eases within a few minutes of sitting or leaning forward is characteristic of stenosis, and that same pattern is what separates it from leg pain caused by poor circulation. An MRI shows where the narrowing is and whether it is in the central canal or in the foramen, the tunnel where the nerve leaves the spine. A CT scan is sometimes added before surgery, because an MRI shows nerves and discs in fine detail while a CT shows bone in fine detail, and knowing whether the structure pressing on the nerve is soft or hard changes how the operation is approached.
One thing worth understanding about the report: when a radiologist grades stenosis as mild, moderate, or severe, that grading is subjective. Dr. Hirsch frequently reviews a study described as severe and finds the narrowing to be mild or moderate. The word on the report does not decide the treatment.
Treatment
Stenosis is treated first without surgery, using the same three categories that apply across most spine problems: anti-inflammatory and other pain medications, physical therapy, and targeted injections such as an epidural steroid injection. Because stenosis comes from structural narrowing rather than from an acute injury, it is less likely to resolve on its own than a disc herniation is, and non-surgical care is often aimed at controlling symptoms rather than reversing the narrowing.
Surgery is considered when a complete course of non-surgical treatment has not been effective, or when weakness, numbness, or balance changes make waiting inappropriate.
Endoscopic and Minimally Invasive Decompression
Decompression makes room for the nerve by removing the thickened ligament, bone, or disc material that is crowding it. Working through an endoscope means the instrument passes between muscle fibers instead of stripping them off the spine.
Decompression of Foraminal Stenosis
When the compression is in the foramen rather than the central canal, the facet joint forms the back wall of that tunnel. Without an endoscope, reaching the nerve has often meant removing that joint, and removing a facet joint destabilizes the segment, which is why a fusion was historically the recommended operation for this problem. The endoscope approaches the foramen at an angle that allows the nerve to be seen and decompressed without taking out the joint, so the segment stays stable and a fusion is often avoidable.
Minimally Invasive Fusion
When the stenosis sits at a level that has also become unstable, or where a vertebra has slipped, stabilizing the segment is part of treating the nerve compression.
Dr. Hirsch is board-certified and Yale-trained. Read his full background.