Spinal Stenosis refers to a narrowing of the spinal canal. Stenosis is when there is compression of the spinal cord in the neck area, called the Cervical Spine, or of the spinal roots in the lower back, referred to as the Lumbar Spine. Stenosis can be a result of age, however, some are born with congenital canal stenosis.
Types of Stenosis
Stenosis can affect the anatomy in different ways. There are three main classifications of Stenosis: Foraminal Stenosis, Central Stenosis, and Lateral Stenosis. However, in general, all forms of Spinal Stenosis are referred to as simply “Stenosis”.
The most common of lumbar spinal stenosis is Foraminal Stenosis. The nerve root exits out of a side hole in the back of the spine, referred to as the neuroforamen. In conditions of degenerating disc or arthritic facet joint, a bone spur can develop and then press on the nerve root as it is leaving the neuroforamen. In the presence of Foraminal Stenosis, that root becomes trapped, and results in the painful pinching of the nerve.
The thecal sac is a membranous sheath of dura mater that surrounds the spinal cord and the bundle of nerves at the end of the spinal cord. Those nerves and nerve rootles in the lumbar area are called the cauda equina, Latin for “horses tail”. The spinal cord, in effect, “floats” inside the cerebrospinal fluid within the thecal sac. Central Stenosis is a narrowing of the central canal in this low back area, which can compress the thecal sac, causing pressure on the cauda equina and affecting individual nerves within the thecal sac.
Far Lateral Stenosis
Often combined with Foramina Stenosis, Far Lateral Stenosis occurs as a narrowing of the area lateral, or to the side of the neuroforamen. Similar to Foramina Stenosis, it is secondary to the formation of bone spurs from facet joints, herniated or bulging discs and ligamentum hypertrophy.