Spinal Stenosis

Spinal stenosis refers to the narrowing of part of the spinal canal, resulting in compression of the spinal cord or nerve roots. This usually affects the cervical or lumbar spine. This section focuses on lumbar spinal stenosis, which is the most common type. 

Spinal stenosis is more likely to occur in patients older than 60 years, relating to degenerative changes in the spine. 

 

Types

There are three types:

  • Central stenosis – narrowing of the central spinal canal
  • Lateral stenosis – narrowing of the nerve root canals
  • Foramina stenosis – narrowing of the intervertebral foramina

 

Causes

Several conditions can cause the spinal canal to narrow, including:

  • Congenital spinal stenosis
  • Degenerative changes, including facet joint changes, disc disease and bone spurs
  • Herniated discs
  • Thickening of the ligamenta flava or posterior longitudinal ligament
  • Spinal fractures
  • Spondylolisthesis (anterior displacement of a vertebra out of line with the one below)
  • Tumours

 

Presentation

Symptoms of spinal stenosis tend to have a gradual onset (as opposed to cauda equina syndrome or sudden disc herniation with cord compression). 

The severity of symptoms will depend on the degree of narrowing and spinal cord. Symptoms may be subtle with mild compression. Severe compression can present with features of cauda equina syndrome (saddle anaesthesia, sexual dysfunction and incontinence of the bladder and bowel), requiring emergency management.

Intermittent neurogenic claudication is a key presenting feature of lumbar spinal stenosis with central stenosis. It is sometimes referred to as pseudoclaudication. Typical symptoms are:

  • Lower back pain
  • Buttock and leg pain
  • Leg weakness

 

The symptoms are absent at rest and when seated but occur with standing and walking. Bending forward (flexing the spine) expands the spinal canal and improves symptoms. Standing straight (extending the spine) narrows the canal and worsens the symptoms.

Lateral stenosis and foramina stenosis in the lumbar spine tends to cause symptoms of sciatica. 

The term radiculopathy refers to compression of the nerve roots as they exit the spinal cord and spinal column, leading to motor and sensory symptoms.

TOM TIP: The important thing for your exams is to spot the typical symptoms of intermittent neurogenic claudication. At first glance, they are similar to peripheral arterial disease. The exam question might specify that the peripheral pulses or the ankle-brachial pressure index (ABPI) are normal, in which case the diagnosis is more likely to be spinal stenosis. Additionally, patients with spinal stenosis are more likely to struggle with back pain, whereas back pain is not a feature of peripheral arterial disease.

 

Investigations

MRI is the primary imaging investigation for diagnosing spinal stenosis. 

Investigations to exclude peripheral arterial disease (e.g., ankle-brachial pressure index and CT angiogram) may be appropriate where symptoms of intermittent claudication are present.

 

Management

Management will be guided by a spinal specialist based on individual factors. Options include:

  • Exercise and weight loss (if appropriate)
  • Analgesia
  • Physiotherapy
  • Decompression surgery where conservative treatment fails (with variable results)

 

Laminectomy refers to the removal of part or all of the lamina from the affected vertebra. The laminae are the bony parts that form the posterior part of the vertebral foramen (forming the spinal canal) and attaches to the spinous process.

The benefits of epidural injections with local anaesthetic and corticosteroids are unclear, and they are not generally used. 

 

Last updated August 2021
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