SIGNS AND SYMPTOMS

The local neck or back symptoms attributed to foraminal stenosis are often associated with inflammation and an underlying disorder whereas the more distant or radiating signs and symptoms are usually associated with spinal nerve compromise within the foramen. The signs and symptoms may involve one or more of the following:

• Numbness
• Tingling
• Muscle weakness
• Radiating pain

The openings along the side of the spine may become narrow (stenotic) without producing symptoms. However, if narrowing places pressure on a spinal nerve root, there may be slow onset progression of symptoms or in some cases acute onset symptoms. The individual may experience local spine pain. There may be numbness, weakness, cramping, or general pain in the arms or legs. Foraminal stenosis in the low back can result in sciatic nerve symptoms (sciatica) characterized by radiating leg pain. If a spinal nerve is compressed within the lateral foramen and is unable to glide to and fro during limb movement the individual may experience nerve root tension signs/symptoms such as radiating extremity pain with limb movement.

CAUSES

The normal vertebral canal provides adequate room for the spinal cord and cauda equina. Normal sized openings along the side of the spine called foramina (neuroforamina) provide adequate room for the spinal nerve roots. Narrowing of the lateral canal, which can occur in spinal stenosis, may be inherited or acquired. It is not uncommon for both the central canal and the lateral openings (canals) to become narrowed. Some people inherit small foramina or have a curvature of the spine (scoliosis) that reduces the dimension of the IVF. This can result in compression of spinal nerves and surrounding soft tissues. It can compress or stretch ligaments. In an inherited condition called achondroplasia, defective bone formation results in abnormally short and thickened bone (pedicles) that reduce the diameter (distance across) of the central and lateral spinal canals.

Foraminal stenosis often develops as a result of a gradual, degenerative aging process affecting the entire spinal segment. Either structural changes or inflammation can begin the process. As individuals age, the ligaments of the spine may thicken and calcify (harden from deposits of calcium salts). The intervertebral disc becomes dehydrated and loses volume. This is most notable on an X-ray, characterized by a loss of vertical disc height. Bones and joints may also enlarge (hypertrophy). When the surfaces of bone begin to project away from the vertebrae, the projections are called osteophytes (bone spurs).

When the health of one part of the spine fails, it will place additional stress on other parts of the spine, usually the adjacent spinal segments. For example, a herniated disk may place pressure on the spinal cord or nerve root. When a segment of the spine becomes hypermobile (unstable), the joint capsules (enclosing membranes) of the spinal facet joints thicken in an effort to stabilize the segment, and bone spurs may occur. This can result in a decreased foraminal dimensions, narrowing the space available for nerve roots leaving the spinal cord.