The Superior Articular Facet (SAF) Syndrome
is a very important pathologic entity because it is frequently
missed diagnostically. Given the fact that
lateral spinal stenosis
itself is often missed diagnostically a real dilemma clearly
exists which can only be solved by better physician and patient
education. This issue is further clouded by the fact that
some luminaries in spine really believe that this is a rare
entity (which is not the case). The SAF syndrome is a type
of lateral spinal stenosis frequently seen in patients with
underlying genomic spine disorders
and characterized by degeneration of facet joints causing the
superior articular facet of the lower vertebra to project into
the foramen and compress the exiting spinal nerve root.
The MRI image seen on the left
demonstrates a classic example of a SAF syndrome.
The superior articular facet of the inferior
vertebrae is projecting into the foramen and in
direct contact with the exiting spinal nerve (green
dot).
Shown below is a case of a 53 year old with a bilateral
lumbar claudication syndrome which progressed to complete
disability due to progressive leg weakness. The MRI
demonstrated a underlying genomic spine disorder. Note the
marked facet joint degeneration (with effusion in the joints)
and a SAF syndrome at both the L4-5 and L5-S1 levels.
Because the tip of the facet joint is quite thin it can only be
reliably and consistently demonstrated by fine MRI cuts in the
saggital plain.
The MRIs shown above are classic for the SAF syndrome.
Fortunately, due to the diligent dedication of physician
anatomist
Wolfgang Rauschning, the microdissections shown below clearly
demonstrating the SAF syndrome exist for educational purposes.
They depict segmental disc degeneration and the beginning of foraminal compromise
with a SAF. In the
image to the left the exiting dorsal root ganglion is shown with a green dot.
The superior articular facet, and its associated hypertrophic ligaments,
have begun to ride up into the
foramen. Note that the nerve is not yet compromised and it is still surrounded by a buffer
of adipose tissue. In the image
to the right the process has continued and the ganglion is flattened
out by the hypertrophied ligmentum flavum. If this process occurs slowly enough the
involved nerve can actually
become almost ribbon-like before clinical symptoms occur. When the
compromise is short-term acclimation does not occur and clinical symptoms
result.
Courtesy of Wolfgang
Rauschning
Shown below is a slide presented at a spine meeting. Examples B.
and C. depict the SAF. The belief "Seldom If Not Rarely
Ever Occurring" is simply incorrect.
