title: Nerve root sedimentation sign for the diagnosis of lumbar spinal stenosis: reliability, sensitivity, and specificity.
abstract: METHODS
  Retrospective review of magnetic resonance images.
  
  
  OBJECTIVE
  Examine the diagnostic accuracy, discriminative ability, and reliability of the sedimentation sign in a sample of patients with clinically diagnosed lumbar spinal stenosis (LSS), low back pain (LBP), and vascular claudication, and in asymptomatic controls.
  
  
  BACKGROUND
  The nerve root sedimentation sign (SedSign) was recently described as a new diagnostic test for LSS; however, the degree to which this sign is sensitive and specific in diagnosis of LSS is unknown.
  
  
  METHODS
  All LSS images were obtained from subjects who had clinically diagnosed LSS confirmed on imaging by a spine specialist. The other images were obtained from people with LBP but no LSS, people with severe vascular claudication, and asymptomatic participants. Three blinded raters independently assessed the images. A positive sign was defined as the absence of nerve root sedimentation at the level above or below the level of maximum stenosis.
  
  
  RESULTS
  Images from 148 subjects were reviewed (67 LSS, 31 LBP, 4 vascular, and 46 asymptomatic). Intrarater reliability for the sign ranged from κ= 0.87 to 0.97 and inter-rater reliability from 0.62 to 0.69. Sensitivity ranged from 42% to 66%, and specificity ranged from 49% to 78%. Sensitivity improved to a range of 60% to 96% when images with only a smallest cross-sectional area of the dural sac less than 80 mm were included. The sign was able to differentiate (P = 0.004) between LSS and asymptomatic controls but not between LSS and LBP or between LSS and vascular claudication.
  
  
  CONCLUSIONS
  The SedSign was shown to have high intrarater reliability and acceptable inter-rater reliability. The Sign appears most sensitive in defining severe LSS cases, yet may not aid in the differential diagnosis of LSS from LBP or vascular claudication, or add any specific diagnostic information beyond the traditional history, physical examination, and imaging studies that are standard in LSS diagnosis.
  
  
  METHODS
  4.
authors: *Department of Physical Education and Recreation Studies, Mount Royal University, Calgary, Canada †Department of Radiology, University of Michigan, Ann Arbor, MI ‡Department of Anesthesiology, University of Michigan, Ann Arbor, MI §Western Australian Institute for Medical Research, University of Western Australia, Perth, Australia; and ¶Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, MI.
authors: Christy C
authors: CC
authors: Tomkins-Lane
authors: Douglas J
authors: DJ
authors: Quint
authors: Shaun
authors: S
authors: Gabriel
authors: Markus
authors: M
authors: Melloh
authors: Andrew J
authors: AJ
authors: Haig
mesh_terms: D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis*; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013126:Spinal Nerve Roots / Q000000981:diagnostic imaging / Q000473:pathology*; D013130:Spinal Stenosis / Q000175:diagnosis*
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