November 2017 Edition. Volume XVII

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.

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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.

White SAF Axial 300

White SAF Lat MRI 300

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.

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Courtesy of Wolfgang Rauschning

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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.

SAF300JPG

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