Permsak Paholpak1,2, Aidin Abedi1, Rattanaporn Chamnan1,3, Kunlavit Chantarasirirat1,4, Koji Tamai1,5, Zorica Buser6, Jeffrey C Wang1. 1. Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. 2. Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand. 3. Department of Orthopaedics, Faculty of Medicine, Prince of Songkla University, Songkla, Thailand. 4. Department of Orthopaedics, Pranangklao Hospital, Nonthaburi, Thailand. 5. Department of Orthopaedics, Osaka City University, Osaka, Japan. 6. Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. zbuser@usc.edu.
Abstract
STUDY DESIGN: Retrospective kinematic MRI (kMRI) study. OBJECTIVE: To evaluate the dynamic changes of thoracic anterior and posterior space available for cord (SAC), and thoracic spinal cord in the dural sac in three positions. SETTING: Expert MRI, Bellflower California; and University of Southern California, in Los Angeles, USA. METHODS: A total of 118 patients (66 males and 52 females, mean age ( ± SD) of 45.6 ± 10.6 years) who underwent thoracic spine kMRI were evaluated from T4-5 to T11-12 in flexion, neutral, and extension positions. The anterior SAC, posterior SAC, and mid-sagittal thoracic cord diameter were measured at each level from T4-5 to T11-12. Inter- and intraobserver agreements were analyzed. RESULTS: The anterior SAC was significantly narrower in flexion position compared with other positions at T8-9 to T11-12 levels (p < 0.01). The T8-9 level had significantly wider posterior SAC in flexion and extension positions compared with the neutral position (p < 0.005). However, the posterior SAC at T9-10 was narrower in extension than the neutral position (p = 0.002). Thoracic spinal cord diameter significantly increased in flexion position when compared with the neutral position at T8-9, T9-10, and T11-12 levels (p < 0.005). CONCLUSIONS: Thoracic spinal cord had dynamic changes with positions. In flexion position, the thoracic cord at T8-9 and below tended to move anteriorly, getting closer to the vertebral body and intervertebral disc. The mid-sagittal diameter of the thoracic cord increased in flexion position at the levels below T8-9. In the presence of lesions in anterior epidural space, the risk of spinal cord compression is higher in flexion position, especially at levels below T8-9.
STUDY DESIGN: Retrospective kinematic MRI (kMRI) study. OBJECTIVE: To evaluate the dynamic changes of thoracic anterior and posterior space available for cord (SAC), and thoracic spinal cord in the dural sac in three positions. SETTING: Expert MRI, Bellflower California; and University of Southern California, in Los Angeles, USA. METHODS: A total of 118 patients (66 males and 52 females, mean age ( ± SD) of 45.6 ± 10.6 years) who underwent thoracic spine kMRI were evaluated from T4-5 to T11-12 in flexion, neutral, and extension positions. The anterior SAC, posterior SAC, and mid-sagittal thoracic cord diameter were measured at each level from T4-5 to T11-12. Inter- and intraobserver agreements were analyzed. RESULTS: The anterior SAC was significantly narrower in flexion position compared with other positions at T8-9 to T11-12 levels (p < 0.01). The T8-9 level had significantly wider posterior SAC in flexion and extension positions compared with the neutral position (p < 0.005). However, the posterior SAC at T9-10 was narrower in extension than the neutral position (p = 0.002). Thoracic spinal cord diameter significantly increased in flexion position when compared with the neutral position at T8-9, T9-10, and T11-12 levels (p < 0.005). CONCLUSIONS: Thoracic spinal cord had dynamic changes with positions. In flexion position, the thoracic cord at T8-9 and below tended to move anteriorly, getting closer to the vertebral body and intervertebral disc. The mid-sagittal diameter of the thoracic cord increased in flexion position at the levels below T8-9. In the presence of lesions in anterior epidural space, the risk of spinal cord compression is higher in flexion position, especially at levels below T8-9.
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