Spinal stenosis is a term that means narrowing of the spinal canal or the nerve root foramina. It is thus divided into central or lateral stenosis. Central stenosis produces compression of the thecal sac. Soft tissue (ligamentum flavum and disc) may contribute as much as 40% to this compression. It is more common in males because their spinal canal is smaller at the L3L5 level.
Lateral stenosis involves impingement of the nerve roots lateral to the thecal sac, as they pass through the neural foramina. It is made worse with hypertrophy (overgrowth) of the ligamentum flavum and / or joint capsule. Foraminal stenosis affects the exiting (upper) nerve root.
Compression of neural structures produces root ischemia and stenosis also compresses vascular supply of nerves so that symptoms are predominantly those of neural ischemia. (Inadequate blood supply to nerves).
There are many different causes of stenosis, the commonest of which is degenerative changes in the spine. This is also referred to as spondylosis, and tends to occur in the older age groups.
However, there are other causes, including congenital or developmental stenosis. This presents at a much earlier age.
A further cause is spondylolisthesis, which is slippage of one vertebra on another, usually caused by degenerative problems or trauma. Stenosis may be posttraumatic or postsurgical.
Stenosis can occur at any level in the spine, but most commonly in the lumbar region. It is the commonest cause of Failed Back Surgery Syndrome (FBSS).
Cervical stenosis is commonly associated with degenerative spinal changes, but can occur as a congenital problem, which may be asymptomatic until a minor injury such as whiplash causes persistent problems.
This is well documented amongst American Football players, who may suffer temporary nerve damage (cord neuropraxia) after injury on the field, or may go on to have recurrent problems, known as the Chronic Burner Syndrome. It is generally accepted that a narrowed cervical spinal canal confers a risk of serious neurological damage from even a minor injury (1,2), especially hyperextension.
Symptoms of cervical stenosis are generally pain, tingling, numbness and weakness in the arms (myelopathic symptoms). In addition, there may be leg weakness, with a heavy feeling in the legs and difficulty walking usual distances or up stairs. Bladder problems may occur, and possibly sexual function may be affected.
Stenosis may also occur at both cervical and lumbar levels. This is known as Tandem Spinal Stenosis (TSS) and is characterised by a triad of intermittent neurogenic claudication, progressive gait disturbances, and findings of mixed myelopathy and polyradiculopathy (multiple nerve root involvement) in both upper and lower extremities. It can mimic other neurological conditions such as amyotrophic lateral sclerosis (ALS). (3) (4).
Thoracic stenosis is relatively rare.