Spinal stenosis is a condition characterized by a narrowing of the spinal canal. This narrowing exerts pressure on the spinal cord and/or spinal nerve roots causing pain, numbness, and other symptoms. The two main types of spinal stenosis are lumbar stenosis and cervical stenosis. Lumbar stenosis is more common.
In lumbar stenosis, the spinal nerve roots in the lower back are compressed, or choked. This can produce symptoms of sciatica -- tingling, weakness or numbness that radiates from the low back and into the buttocks and legs -- especially with movement and activity. Cervical spinal stenosis can be more dangerous because the spinal cord is compressed. Symptoms of cervical spinal stenosis include numbness, weakness or tingling in a leg, foot, arm or hand, neck or shoulder pain. Cervical spinal stenosis can lead to loss of bowel or bladder control, major body weakness or even paralysis in severe cases.
The main causes of stenosis include thickening of the spinal ligaments, bone spurs, herniated discs, and spinal injury. Thickening of the spinal ligament is usually caused by facet joint arthritis. Inflammation of the facet joints causes stress on the joints that may lead to osteoarthritis. The facet joint arthritis can cause biomechanical stress, leakage of inflammatory cytokines, and scarring leading to the thickening of the ligaments resulting in narrowing of the spinal canal.
The facet joint arthritis can also cause stenosis by causing bone spur formation inside the spinal canal. Carboxylated matrix Gla protein (MGP) can inhibit bone spur formation by inhibiting calcium deposition and suppressing Bone morphogenetic protein (BMP), a bone growth hormone. Osteoarthritic joints produce hypertrophic chondrocytes in the cartilage tissue that are unable to carboxylate the MGP. MGP that is un-carboxylated cannot prevent calcium deposition in the spinal canal and is unable to inhibit extra bony growth through suppression of Bone morphogenetic protein (BMP), leading to bone spur formation.
A liver deficiency can also cause bone spurs and stenosis because of the resulting vitamin K deficiency. Carboxylation of MGP is a vitamin K dependent process. Dietary vitamin K is absorbed through the intestines using bile salts that are produced by the liver. A liver deficiency can cause reduced bile production which can result in a vitamin K deficiency. With inadequate supply of vitamin K, the MGH cannot be carboxylated leading to bone spur and stenosis.
Herniated discs or bulging discs may cause stenosis when the ruptured contents of herniated or bulging discs press against the spinal cord or
spinal roots. Spinal injury may causes stenosis through dislocation of vertebrae, slipped discs, or
swelling of peripheral tissue to compress the spinal cord or roots.