What is spinal stenosis?

What it is

NIAMS, a US National Institutes of Health institute, describes spinal stenosis as narrowing of the spaces in the spine that creates pressure on the spinal cord and nerve roots. The spinal cord is the bundle of nerves running down the center of the spine, and nerve roots are the branches that leave it. The narrowing can occur in the central canal, at the base of the nerve roots, or in the openings between vertebrae through which nerves exit.

It most commonly develops in the lower back (lumbar spine) and the neck (cervical spine). NIAMS says it usually happens over time. Mayo Clinic adds that most people with spinal stenosis are older than 50. NIAMS says younger people can be affected too, for example if they were born with a narrow spinal canal or have had a spine injury.

Symptoms

Many people have no symptoms, and when they appear they typically start slowly. In the lower back, NIAMS lists back pain, burning pain or aching that spreads into the buttocks and legs, numbness, tingling or cramping, and weakness in the legs and feet. A well-known feature is that symptoms often get worse with standing or walking and ease when leaning forward or sitting, because bending forward opens up the space in the spine.

In the neck, NIAMS and Mayo Clinic list neck pain, numbness or tingling that travels into the arms and hands, and weakness in a hand, arm or fingers. Mayo Clinic also lists trouble with walking and balance and with fine tasks such as writing or using a knife and fork. NIAMS says people with more severe stenosis may also have bowel, bladder or sexual problems.

Causes

Age-related change in the spine is the most common cause, according to NIAMS. Ligaments can thicken and harden, joints and bones can enlarge and form bone spurs, and a disc can dry out and bulge. Arthritis, especially osteoarthritis, is another common cause. Less often, injuries, tumors, Paget's disease of bone and inherited conditions such as scoliosis play a role.

A bulging or herniated disc is one of the possible contributors, which links stenosis to the topics in What is a slipped disc? and, when a nerve in the leg is affected, What is sciatica? Both sit within the set Discs and nerves.

Diagnosis and treatment

Clinicians start with your history and a physical exam that checks movement, sensation, strength, reflexes, balance and walking. NIAMS says X-rays, MRI and CT can each show different structures. It also states that imaging alone will not determine whether spinal stenosis requires treatment, which fits the wider point about scan findings in Are disc changes on an MRI normal?

NIAMS lists physical therapy, a brace in some cases, medicines and injections as non-surgical options. If symptoms continue, a doctor may suggest meeting a surgeon. NIAMS notes that not everyone is a candidate for surgery, that most people have less leg pain and walk better afterward, and that pain or numbness may remain if nerves were badly damaged beforehand. MedlinePlus likewise lists medicines, physical therapy, braces and surgery. Choices differ between countries and clinicians.

When to get help

Numbness, tingling, weakness or leg or arm pain that keeps returning, or that makes walking or daily tasks harder, deserves a conversation with a doctor. NIAMS says doctors may recommend surgery right away, rather than after trying other treatments, when numbness or weakness interferes with walking or when bowel or bladder function is impaired.

The NHS advises calling 999 or going to A&E (use your local emergency number elsewhere) for back pain with numbness around the bottom or genitals, being unable to pee, losing feeling in one or both legs, or being unable to control urine or stool. Mayo Clinic describes bladder or bowel changes as a rare effect of lower back stenosis. When is back pain an emergency? covers these signs in more detail. Practice varies by country and by clinician.