Spinal Stenosis

Authored by Dr Colin Tidy, 22 Feb 2017

Patient is a certified member of
The Information Standard

Reviewed by:
Dr Hayley Willacy, 22 Feb 2017

Spinal stenosis is a term used to describe a narrowing of the spinal canal. The narrowing may not cause any symptoms. However, the narrowing may progress to cause squeezing (compression) of the spinal nerves or compression of the spine. Spinal stenosis causes back pain and leg pain. Most often it occurs when you walk. Weakness of the legs may make you feel unsteady. This may affect both legs or just one leg. Spinal stenosis affecting the cervical spine in your neck may also cause pain and weakness in the shoulders and arms.

Spinal stenosis can often be treated by simple measures such as medicines for pain relief, keeping as active as you can and losing weight if you are overweight. Sometimes steroid injections or surgery are needed if simple measures are not successful.

The spine is made up of many bones called vertebrae. These are roughly circular and between each vertebra is a disc. The discs are made of strong rubber-like tissue which allows the spine to be fairly flexible. A disc has a stronger fibrous outer part and a softer jelly-like middle part called the nucleus pulposus.

The spinal cord, which contains the nerves that come from the brain, is protected by the spine. Nerves from the spinal cord come out from between the vertebrae to relay messages to and from various parts of the body.

Whole spinal cord
Lumbar spinal cord

Spinal stenosis is a term used to describe a narrowing of the spinal canal. The narrowing may not cause any symptoms. However, the narrowing may progress to cause squeezing (compression) of the spinal nerves or compression of the spine. Narrowing that affects the spinal cord is sometimes called a myelopathy. More than one level of the spine may be affected. The blood supply to the nerves in the spine may also be temporarily reduced by the compression.

The lower end of the spinal cord is at the level of the first or second lumbar bone (vertebra). The nerves from the spinal cord then form a structure called the conus medullaris. The spinal nerves continue to branch out below the conus medullaris to form the cauda equina. Pressure on the cauda equina causes cauda equina syndrome. Cauda equina syndrome may cause low back pain and problems with bowel and bladder function, numbness in the saddle area, which is around the back passage (anus), and weakness in one or both legs. Cauda equina syndrome needs urgent investigation and treatment to prevent the nerves to the bladder and bowel from becoming permanently damaged.

Usually, as part of the normal ageing process, degenerative changes occur in the spine, especially in the lower back and neck. Sometimes this causes partial compression (stenosis) of the nerve tunnel within the spine. This is called central stenosis. Sometimes there is a constriction to the smaller side tunnels with the spine. This is called foraminal stenosis.

Spinal stenosis is common, especially in older people. However, it can also rarely affect younger people. Spinal stenosis most often affects the lower (lumbar) spine. The next most commonly affected part of the spine is the cervical spine in the neck. Stenosis of the spine at the back of your chest (thoracic spine) is much less common.

Spinal stenosis causes back pain and leg pain. Most often it occurs when you walk. Weakness of the legs may make you feel unsteady. This may affect both legs or just one leg. Spinal stenosis affecting the cervical spine may also cause pain and weakness in the shoulders and arms.

Claudication is the term used to describe weakness of the legs that becomes worse specifically on walking. Claudication is caused either by narrowing of the blood vessels suppplying the leg or because of spinal stenosis.

Usually spinal stenosis prevents you from walking beyond a certain distance. You then have to stop because of increasing pain and numbness in one or both of your legs. The symptoms can also occur when standing. Usually the symptoms reduce if you sit down or lean forwards. There is usually no pain when you are resting.

Walking usually only aggravates the leg symptoms. The back pain caused by spinal stenosis does not increase with walking.

If your doctor thinks that you may have spinal stenosis then an MRI scan will be arranged to confirm the diagnosis.

How you can help to improve your own symptoms

Other available treatments

Spinal injectionsinjections of a steroid with local anaesthetic given into the spinal root canal or given by epidural injections can be helpful.

Surgery: if symptoms still do not improve then one option is surgery. The most commonly used operation is called a decompression. The bone that is compressing the nerves is removed so that the nerves have more room. The two bones (vertebrae) may also be fused together (this is called spinal fusion).

There is very limited evidence for surgery to treat spinal stenosis. The success of surgery for spinal stenosis is variable. Although the symptoms may improve just after the operation, the medium-term and long-term results can be disappointing.

Interspinous distraction: this procedure involves placing an implant between the spinous processes of the affected vertebrae (usually the fourth and fifth lumbar vertebrae) in order to limit you extending your back. This helps to prevent or reduce the pain in your legs when standing or walking.

The outcome is very variable and, without treatment, the symptoms usually gradually become worse. Although treatments for spinal stenosis are often effective at reducing symptoms, the symptoms don't usually completely resolve.

Further reading and references

Please advise - has your back pain due to the spine pressing on a root nerve gone in time or with physio’s help, or did you need an operation to be pain free?My lower back pain comes at night when I’...

JeremySt
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