Spinal Canal Stenosis
Spinal canal stenosis, commonly called spinal stenosis, is a narrowing of the spaces within the spine that can put pressure on the spinal cord and nerves. This narrowing most commonly occurs in the lower back (lumbar spine) and neck (cervical spine) and typically develops gradually over time due to age-related degenerative changes. As the spinal canal narrows, it can compress neural structures, leading to pain, numbness, weakness, and balance problems. Spinal stenosis is one of the most common reasons for spine surgery in adults over 60.
What is it?
The spinal canal is the hollow space within the vertebrae that houses and protects the spinal cord in the cervical and thoracic regions, and the cauda equina (bundle of nerve roots) in the lumbar region. Spinal stenosis occurs when this space becomes narrowed, reducing the available room for neural structures. This narrowing can occur at different levels: central canal stenosis involves narrowing of the main spinal canal; lateral recess stenosis affects the sides of the canal where nerve roots exit; and foraminal stenosis involves narrowing of the neural foramina (the openings between vertebrae through which spinal nerves pass).
Spinal stenosis is classified as either acquired (developing over time) or congenital (present from birth). Acquired stenosis, which is far more common, results from age-related degenerative changes including osteoarthritis causing bone spurs (osteophytes), thickening of ligaments (particularly the ligamentum flavum), bulging or herniated discs, facet joint arthropathy, and spondylolisthesis (vertebral slippage). Congenital stenosis occurs when someone is born with a naturally narrow spinal canal, making them more susceptible to symptomatic stenosis with even minor degenerative changes. Risk factors include age over 50, previous back injury or surgery, long-standing occupation involving repetitive stress on the spine, and certain conditions like Paget’s disease or achondroplasia. Lumbar stenosis is most common, typically affecting the L4-L5 and L3-L4 levels, while cervical stenosis most often occurs at C4-C5, C5-C6, and C6-C7.
Important to Know
Lumbar spinal stenosis classically causes neurogenic claudication—leg pain, cramping, numbness, or weakness that worsens with walking or standing and improves with sitting or bending forward (flexion opens up the spinal canal). Patients often report being able to walk farther when leaning on a shopping cart or walking uphill (both involve spine flexion) compared to walking upright. Back pain may or may not be present. Cervical stenosis can cause neck pain, but more concerning is myelopathy—spinal cord compression causing hand clumsiness or difficulty with fine motor tasks, gait instability and imbalance, bowel or bladder dysfunction in severe cases, and weakness or numbness in the arms or legs. Some patients have stenosis visible on imaging but experience no symptoms, while others with relatively mild narrowing have significant symptoms. Diagnosis is confirmed with MRI, which provides detailed visualization of soft tissues including the spinal cord, nerve roots, discs, and ligaments. CT myelography (CT after contrast injection into the spinal fluid) is an alternative when MRI cannot be performed. X-rays show bony changes but cannot visualize neural compression. Treatment begins conservatively with physical therapy focusing on flexion-based exercises and core strengthening, medications including NSAIDs and neuropathic pain medications, and epidural steroid injections to reduce inflammation around compressed nerves. Surgery (decompressive laminectomy, with or without fusion) is considered when conservative treatments fail and symptoms significantly impact quality of life, or when there are signs of progressive neurological deficit or myelopathy. Surgical outcomes are generally good for carefully selected patients, with most experiencing significant symptom relief. Without treatment, lumbar stenosis typically follows a variable course—some patients remain stable, while others experience gradual worsening. Cervical myelopathy, however, often progresses if left untreated and may lead to permanent spinal cord damage, making timely intervention more critical.