Rade M. et al. 2014 Young Investigator Award: In Vivo Magnetic Resonance Imaging Measurement of Spinal Cord Displacement in Thoracolumbar Region of Asymptomatic Subjects. Part 2: Comparison between Unilateral and Bilateral Straight Leg Raise Tests
Spine: 2014
- Using the same methods as in the previous study of in vivo measurement of spinal cord displacement with the unilateral straight leg raise (SLR) in asymptomatic subjects, the authors further measured cord displacement during the passive bilateral SLR, comparing these data with the unilateral SLR.
- Measurements were taken twice by the main author, 2 months apart, and once by the coauthor (J.M.) for evaluation of intra- and interobserver reproducibility
- Subjects were scanned in the following positions:
• Neutral : Lying supine, aligned symmetrically, lower limbs extended, and relaxed.
• Passive bilateral SLR : maximum hip fl exion allowed by the MR. Two investigators were required for this in which subjects’ legs were raised, one by one, starting from the
right, left or both legs together in a random order.
- Because of the MR device, architecture with a tube diameter of 60 cm, only 50 ° of hip flexion was able to be achieved
- When compared with the position in the neutral (anatomic) position, the medullar cone displaced caudally in the spinal canal by 4.58 ± 1.48 mm with bilateral SLR
- This displacement was also statistically significant when compared with the right SLR ( P ≤ 0.001) and left SLR ( P ≤ 0.001) in which the medullar cone displaced by 2.31 ± 1.2 mm and 2.35 ± 1.2 mm, respectively
- With these results, the authors hypothesize that the sliding of neural structures in the vertebral canal may be a protective effect that preserves the spinal cord and neural roots from strain.
- It is also possible that the quantification of neural displacement in response to neural tension tests as unilateral or bilateral SLRs may form a valuable aspect of selection of patients for conservative treatment or surgery.
- They also offer baseline measurements on which further studies in diagnosis and treatment of lumbar disc protrusion and radiculopathy with the SLR may be developed. In particular, evaluation of relationships between cord and nerve root movement may be a useful tool for investigation of patients with back pain and sciatica.
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