This is a narrowing of the spinal canal, which places pressure on the spinal cord.  Most commonly, it is located either on the lower part of the spinal cord (lumbar spinal stenosis), or upper part of the spinal cord (cervical spinal stenosis).  The condition may be inherited and evident at birth or later in life, typically after age 50.  With ageing, the ligaments of the spine can thicken and harden (called calcification).  Bones and joints may also enlarge, and bone spurs (called osteophytes) may form.  Slipped discs or spondylolisthesis can also lead to compression in the spinal area, causing narrowing of the spinal canal and pressure on the spinal nerve.  

Patients with lumbar spinal stenosis may feel pain, weakness, or numbness in the legs, calves or buttocks.  In the lumbar spine, symptoms often increase when walking short distances and decrease when the patient sits, bends forward or lies down.  Cervical spinal stenosis may cause similar symptoms in the shoulders, arms, and legs; hand clumsiness and gait and balance disturbances can also occur.  Pain may radiate like sciatica or may be a cramping pain.  Severe cases of stenosis can cause constant pain, bladder and bowel problems, but this rarely occurs.  Paraplegia or significant loss of function are extremely rare risks.