What is actually happening

Spinal stenosis is a narrowing of the space available for the nerves that run through your low back — the central canal, the foramen where a root exits, or both. Two biological processes usually build it together: disc bulging that loses height and pushes into the canal, and thickened, arthritic facet joints and ligament that crowd it from behind. Neither alone is dramatic; together, over years, the space closes. A third driver, less discussed, is sarcopenia — age-related loss of the deep spinal muscles that normally hold the vertebrae in better alignment. Less muscular support lets the segment sag into extension, which is exactly the position that narrows the canal further, so a body that has lost muscle mass narrows its own canal mechanically on top of the arthritic changes already present.

Distance, not minutes

The classic complaint is leg heaviness, cramping or pain that builds predictably after walking a consistent distance — two blocks, one aisle of a store — and eases within minutes of sitting or leaning forward, which opens the canal. Vascular claudication, from narrowed arteries rather than a narrowed canal, is triggered by exertion regardless of posture and does not care whether you are standing upright or bent over a cart; it improves with rest alone, not with flexion specifically. A detailed 2019 review in Pain Medicine lays out this distinction as the core of the diagnosis: ask what position relieves it, not just how far the person can walk, because the position is what separates a spine problem from a circulation problem before any imaging is ordered.

How we confirm it

History does most of the work — the distance, the posture that relieves it, whether a bicycle (which keeps you flexed forward) is tolerated far better than walking upright, which is a near-diagnostic detail on its own. MRI confirms the anatomic narrowing and its location, but stenosis on a scan is common in older spines that are not symptomatic, so the imaging is read against the exam and the walking history, not treated as the diagnosis by itself. Where the picture is mixed with a vascular contributor, we coordinate rather than guess.

The injection’s role

An epidural steroid injection reduces the inflammatory swelling around compressed roots, and a 2025 AAN guideline summary in Neurology supports its use specifically for stenosis-related radicular pain as a way to create a window for function. It does not widen the canal — nothing injected does — but reducing the inflammatory component can extend how far you walk and how much conditioning work becomes tolerable, which matters because deconditioning from avoiding walking is its own separate problem layered on top of the anatomy.

The decompression conversation

Unlike a disc fragment, a bony and ligamentous canal does not resorb on its own, so stenosis is a more patient but also more mechanical conversation than a herniation is. A 2022 systematic review in BMJ Open found meaningful benefit from non-operative care — targeted exercise, injections, activity pacing — for a real proportion of patients, and a Cochrane review comparing surgical to non-surgical treatment found surgery outperforms conservative care for moderate to severe stenosis over the following one to two years, though the gap narrows over longer follow-up. Surgery is not automatic here, but it is a legitimate and frequently correct part of the plan for stenosis specifically, more often than it is for a resorbable herniation, once conservative and interventional measures have been given a real trial and walking distance is not improving.

The metabolic terrain of an older spine

Stenosis mostly shows up in a spine that has also been losing muscle and bone quality for years, and treating the canal without treating that terrain leaves half the problem in place. Sarcopenia is addressed with resistance work scaled to what stenosis allows, and systemic inflammation — more common in a population where metabolic disease is common — is addressed because it accelerates the same facet arthritis and ligament thickening that built the narrowing in the first place. Sleep, movement and behavior covers the conditioning side of this in detail.

Red flags, in plain terms

Common questions

Related reading

• Sciatica
• Herniated disc
• Epidural steroid injection
• Failed back surgery syndrome
• Metabolic health and pain