Description

• A condition characterized by narrowing of either the central spinal canal, lateral recess, and/or neural foramen
• Symptoms may include pain, numbness, tingling, and muscle weakness.

Epidemiology

Prevalence
The prevalence of acquired spinal stenosis increases with age.

• Approximately 11–38% of adults will have some degree of lumbar stenosis on imaging (aged 19 to 93 years; mean age 62 years) (1).
• Lumbar spinal stenosis affects more than 200,000 people in the United States and is one of the most common reasons for spinal surgery in patients >65 years old (2).

Etiology and Pathophysiology

• Spinal stenosis can result from congenital or acquired causes (1).
  • Congenital spinal stenosis:
    • Developmentally short pedicles, achondroplasia, spinal dysraphism, spina bifida, and spondyloepiphyseal dysplasias.
  • Acquired spinal stenosis
    • Spondylosis, spondylolisthesis (degenerative or due to pars interarticular fracture), trauma, postoperative changes, inflammatory arthropathy (e.g., ankylosing spondylitis, rheumatoid arthritis), and space-occupying lesions (tumors, cysts)
• The most common cause of acquired spinal stenosis is degenerative spondylosis.
  • May involve the lumbar, cervical, thoracic spine (in order of prevalence)
    • Within the lumbar spine, the L4–L5 and L5–S1 levels are the most frequently involved.
  • Degenerative changes leading to spinal cord and nerve root compression include disc degeneration, facet arthropathy, osteophyte formation, and ligamentum flavum hypertrophy (3).
    • Disc dehydration leads to loss of height with bulging of the disc annulus and ligamentum flavum into the spinal canal.
    • Increased facet loading causes reactive sclerosis and osteophyte formation which compresses neural structures.
  • Not all patients with radiographic spinal stenosis are symptomatic, and the degree of radiographic stenosis does not always correlate with the patients symptoms.
  • Symptomatic spinal stenosis is likely caused by mechanical compression and ischemia of spinal nerve roots. Increased intrathecal pressure may also lead to development of symptoms (3).

Risk Factors

Spinal trauma, spinal surgery, spine inflammatory arthropathy, vitamin B12 deficiency, osteoporosis, renal osteodystrophy, Cushing disease, acromegaly, and Paget disease

Commonly Associated Conditions

• Cervical or lumbosacral radiculopathy
• Degenerative spondylolisthesis
• Pars interarticular fracture
• Scoliosis
• Cauda equina syndrome