Spinal Stenosis Causes and Developments
Complex changes in the vertebral structures and ligaments of the spine contribute to the development of acquired lumbar spinal stenosis. As the body dehydrates with age, bones become less dense and the discs of thespine lose mass. The discs compress, causing tilting, slippage and rotation of vertebral bodies. This results in compression of the spinal sac and nerve roots. In some cases, bone growth is stimulated and osteophytes form in the lateral recess and intervertebral foramina as the spine tries to stabilize itself. This can cause compression of nerve roots as they exit through the foramina to the lower back and legs, leading to chronic back pain and intermittent weakness and numbness in the legs.
At the same time, hypertrophy of the spinal ligaments (ligamentum flavum) can reduce the space available for the spinal sac, causing further compression of the nerve roots. These ligaments stiffen with age and begin to buckle into the spinal canal, creating additional points of compression and pain. Arthritis often compounds the problem by increasing the stiffness and inflexibility of the ligaments and joints.
In addition to the body’s dehydration with age, the physiological changes responsible for LSS are thought to have their genesis in four areas.
Listed from most common to rare:
- Degenerative causes such as spondylosis, spondylolisthesis, hypertrophy of the ligamentum flavum, and synovial cysts are the main etiology of LSS by far.
- Traumatic causes such as vertebral fractures and subluxation, complications following laminectomy such as epidural fibrosis and herniated discs.
- Skeletal causes such as metastatic cancer of the spine, rheumatoid arthritis, Paget’s disease, ankylosing spondylitis and diffuse idiopathic skeletal hyperstosis (DISH).
- Metabolic and endocrine causes such as acromegaly, pseudogout, renal osteodystrophy, hypoparathyroidism or, in rare cases, Cushing’s disease.