Peleg Ben-Galim and Charles A. Reitman
Symptoms of spinal stenosis are position-dependent. Stand up magnetic resonance imaging (MRI) and myelography can demonstrate further dynamic components of spinal stenosis that may go unrecognized on supine MRI. The purpose of this study was to describe a radiographic finding seen on standard supine MRI that is an indicator for dynamic spinalstenosis and degenerative spondylolisthesis. Six patients with classic neurogenic claudication but equivocal supine MRIfindings were evaluated with myelography. The results showed that all patients had severe position-dependent spinal stenosis upon upright myelographic imaging with grade I or II spondylolisthesis. The MRI showed very minimal to no spondylolisthesis. These dynamic slips reduced when supine, causing the vertebral bodies to appear aligned with adequate canal space, whereas the irregular facet joints became distended. Hypertrophic and fluid-filled facets at the dynamic slip level were seen in allpatients, giving the appearance of a distended joint. The authors conclude that MRI may not demonstrate significant stenosis in patients with neurogenic claudication caused by dynamic degenerative spondylolisthesis. However,the presence of large fluid-filled facet joints indicates the likelihood of positional translation at that level which could befurther confirmed by upright imaging.
The Spine Journal,Volume 7, Issue 2,