By Mr Ahmed-Ramadan Sadek, Neurosurgeon · Last reviewed October 2026 · 6 min read

What is lumbar spinal stenosis?

Stenosis simply means narrowing. In the lower back (the lumbar spine), the nerves to the legs travel down a central tunnel called the spinal canal, then exit through smaller side openings called foramina. When either space becomes tight, the nerves can be squeezed and their blood supply temporarily reduced.

Narrowing in the middle is known as central stenosis; narrowing of the side openings is foraminal stenosis. In practice, both tend to cause similar symptoms, and some people have narrowing at more than one level.

Symptoms

The classic pattern is called neurogenic claudication. After walking a certain distance, pain, aching, heaviness, tingling or numbness builds up in the buttocks and legs, sometimes on one side, sometimes both, and you have to stop. the British Association of Spine Surgeons (BASS) describes this distance as varying widely, from around 50 metres to perhaps 500 metres.

• Symptoms ease after sitting down or leaning forward, for example over a shopping trolley.
• Standing still for a while can bring them on too.
• The legs are usually comfortable when you are resting.
• Some people feel unsteady or notice their legs feel weak.

Bending forward opens the spinal canal slightly, while standing upright narrows it, which explains why posture matters so much. Many people also have back ache, but back pain that worsens with walking is not itself a typical feature of stenosis.

What causes it?

Most stenosis is part of normal ageing. Over time, discs lose water and height and may bulge, the small facet joints at the back of the spine thicken with arthritis and develop bony spurs (osteophytes), and a ligament lining the back of the canal, the ligamentum flavum, buckles inwards. Together these crowd the nerves. A forward slip of one vertebra on another (degenerative spondylolisthesis) can add to the narrowing. Cysts, fatty tissue or tumours are much rarer causes.

Diagnosis

Your GP will usually suspect stenosis from your description and an examination, then refer you to a spinal specialist. An MRI scan confirms the narrowing and shows which levels are affected; a CT scan is occasionally used instead.

Some other conditions can mimic stenosis. Narrowed leg arteries (vascular claudication), particularly in smokers, can cause leg pain on walking. Diabetes and low vitamin B12 can cause numbness and unsteadiness, and a simple blood test can check for these.

Will it get worse?

The course is hard to predict for any one person. As a rough guide, BASS suggests that about 1 in 5 people improve over time, 3 in 5 stay much the same and 1 in 5 gradually get worse, usually with walking distance shrinking or nerve symptoms increasing.

Treatment options

Stenosis is essentially a quality-of-life condition. If your symptoms are bearable, you may not need any treatment at all. Most specialists start with the simplest, lowest-risk measures.

Exercise and staying active

• Exercise bike: because you lean forward, cycling is often more comfortable than walking. Start with two or three minutes twice daily and build up slowly every few days.
• Walking: going to the point where symptoms begin and then a little further can, over time, increase how far you can manage.
• Regular exercises to keep the spine supple and strong.
• Losing weight if you need to, and stopping smoking.

Being fitter also makes any future operation safer. It can take a few months to tell whether these measures are working.

Medicines

Paracetamol and anti-inflammatories can help, and combining different types often works better than relying on one. Your doctor may also prescribe a medicine that calms nerve pain, such as amitriptyline or gabapentin.

Injections

An epidural places steroid and local anaesthetic into the spinal canal and tends to help leg pain more than back pain. A nerve root injection targets a single nerve and is particularly useful when one leg is affected. BASS web guidance estimates that about 60% of patients respond well to these low-risk injections, which can be repeated.

Surgery

If symptoms remain unacceptable or worsen despite simpler treatment, surgery is worth considering. The BASS surgical booklet cautions that non-surgical treatments rarely bring lasting relief once stenosis is significant. The standard operation is a decompression: through a cut in the middle of the lower back, the surgeon removes part of the bony roof of the canal (laminectomy) or makes a smaller window in it (laminotomy), trims thickened ligament and undercuts the facet joints to free the nerves. Some surgeons use a minimally invasive technique through a narrow tube. Results are similar, and your surgeon will advise which suits you. See our guide to lumbar decompression.

According to the BASS booklet, around 70 to 80% of people (up to 8 in 10) get good relief of leg symptoms, often building over several months. Back pain responds much less predictably. Numbness or weakness present before surgery may persist, especially if the stenosis was severe, and occasionally symptoms end up worse.

For selected patients, a smaller procedure placing a spacer between the bony projections at the back of the spine (an interspinous device) may be an option. BASS notes that people who can stay seated for roughly 30 minutes with comfortable legs may be suitable.

Risks of decompression surgery

The following figures are taken from the BASS patient booklet on lumbar spine stenosis surgery.

Risk	Approximate frequency (BASS)
Nerve root injury, first operation	Less than 1 in 100
Nerve root injury, repeat surgery	Up to 10 in 100
Tear in the nerve lining (dura)	Fewer than 5 in 100 (more common in repeat surgery)
Further operation to repair a persistent fluid leak	Less than 0.05%
Superficial wound infection	Up to 4 in 100
Deep wound infection	Fewer than 1 in 100
Blood clot in the leg or lung (DVT/PE)	Fewer than 1 in 700
Death from damage to major vessels or organs	About 1 in 10,000
Death from anaesthetic complications	About 1 in 250,000

Other risks include leg pain returning due to scar tissue, bleeding, positioning injuries (very rarely affecting eyesight), stroke or heart attack, and, very rarely, paralysis or loss of bladder and bowel control from bleeding within the spinal canal.

Recovery

BASS reports that most people go home 1 to 2 days after decompression. Leg pain can take eight weeks or longer to settle, while strength and sensation may keep improving for a year or so. Driving is usually avoided for about four weeks, and most people return to work after four weeks, or up to eight for heavy jobs. Keep walking regularly and avoid heavy lifting in the early weeks.

• BASS patient information: Spinal stenosis
• BASS patient booklet: Lumbar spine stenosis
• NHS: Spinal stenosis
• Spinemathema guide: Lumbar discectomy and decompression

This guide is general information and is not a substitute for advice about your own situation. Please speak to your GP or specialist.