الفهرس 
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Abstract
Lumbar canal stenosis (LCS) is one of the most frequent problems requiring surgical interventions, Despite the availability of a wide range of clinical, electrophysiological, and imaging modalities for the diagnosis of this syndrome, the indication for surgery has not yet approved, and guidance for clinicians is inconsistent and inadequate.(2) we need additional diagnostic modalities to enhance the detection of LCS and to provide a guidance for surgical interventions. The absence of clinical manifestations at rest and there relation to activity settle a difficulty in detection of LCS.
Barz et al has discovered a sign concerning the nerve roots, while the normal person is in the supine position the lumbar nerve roots will deposit posteriorly in the thecal sac by the effect of gravity, this deposition is rarely detected in individuals suffering from LCS, Barz called this phenomenon as the sedimentation sign (S.S). In those patients with LCS, the nerve root would not be able to deposit but disperse anteriorly. The NRS sign has been observed to distinguish well between individuals with and without LCS and reported to be 98.1% sensitive and 82.6% specific. However, the sign is not famously used probably due to its limited reliability study. Barz defined positive sedimentation sign as the absence of nerve root sedimentation in at least one axial MRI scan, at a level above or below, neglecting the location of the scan within the level and its proximity to the maximal stenosis.
This study involved the assessment of 55 patients suffering from lumbar canal stenosis, 51 patients out of them had their sedimentation sign positive, and only 4 patients had their sedimentation sign negative,
The high sensitivity and specificity (92.7%) of this new radiological sign make it valuable in the diagnosis of lumbar canal stenosis.