title: 2014 young investigator award winner: In vivo magnetic resonance imaging measurement of spinal cord displacement in the thoracolumbar region of asymptomatic subjects: part 2: comparison between unilateral and bilateral straight leg raise tests.
abstract: METHODS
  Controlled radiological study.
  
  
  OBJECTIVE
  Ascertain if a difference exists in the mechanical effects on the cord between the unilateral and bilateral straight leg raise (SLR) and to verify whether the effect on the spinal cord may be cumulative between the two.
  
  
  BACKGROUND
  To the authors' knowledge these are the first data on noninvasive, in vivo, normative measurement of spinal cord displacement with bilateral SLR test.
  
  
  METHODS
  Sixteen asymptomatic volunteers were scanned with 1.5-T magnetic resonance scanner (Siemens Avanto, Erlangen, Germany) using T2-weighted turbo spin-echo fat-saturation sequence. The displacement of the medullar cone relative to the vertebral endplate of the adjacent vertebra during the passive bilateral SLR was quantified and compared with the position of the conus in the neutral (anatomic) position and with unilateral SLR. Each movement was performed twice for evaluation of reproducibility. The measurements were repeated by 2 observers. Four practitioners performed the maneuvers in a random sequence to avoid series effects.
  
  
  RESULTS
  Compared with the neutral (anatomic) position, the medullar cone displaced caudally in the spinal canal by 2.33 ± 1.2 mm (μ ± SD) with unilateral (P ≤ 0.001) and 4.58 ± 1.48 mm with bilateral SLR (P ≤ 0.001). Statistical significance was also reached for bilateral versus unilateral SLR (P ≤ 0.001). Spearman correlations proved higher than 0.99 for intra and interobserver reliability, and 0.984 for results reproducibility in bilateral SLR.
  
  
  CONCLUSIONS
  The caudal displacement of the medullar cone was significantly greater (almost double) with the bilateral SLR than the unilateral SLR. We hypothesize that this greater movement may be because more force was transmitted to the cord through a larger number nerve roots with the bilateral than unilateral SLR. The high correlation values in this study show that these movements are consistent and reproducible. This study offers baseline measurements on which further studies in diagnosis and treatment of lumbar disc protrusion and radiculopathy may be developed.
authors: *Department of Physical and Rehabilitation Medicine, Kuopio University Hospital, Kuopio, Finland †"Prim. dr.Martin Horvat" Orthopaedic and Rehabilitation Hospital, Rovinj, Croatia ‡Department of Radiology, Kuopio University Hospital, Kuopio, Finland §Neurodynamic Solutions, Adelaide, Australia; and ¶Department of Physical and Rehabilitation Medicine, Tampere University Hospital, Tampere, Finland.
authors: Marinko
authors: M
authors: Rade
authors: Mervi
authors: M
authors: Könönen
authors: Ritva
authors: R
authors: Vanninen
authors: Jarkko
authors: J
authors: Marttila
authors: Michael
authors: M
authors: Shacklock
authors: Markku
authors: M
authors: Kankaanpää
authors: Olavi
authors: O
authors: Airaksinen
mesh_terms: D000328:Adult; D001363:Awards and Prizes; D006801:Humans; D007866:Leg / Q000294:innervation / Q000502:physiology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015203:Reproducibility of Results; D012108:Research Personnel; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000000981:diagnostic imaging*; D013118:Spinal Cord Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging; D013126:Spinal Nerve Roots / Q000502:physiology; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging*