Dynamic Evaluation of the Cervical Spine and the Spinal Cord of Symptomatic Patients Using a Kinetic Magnetic Resonance Imaging Technique.
OBJECTIVE
The purpose of this study was to examine the movement of the spinal cord and its relationship to the spinal canal in patients with mild spondylosis using kinetic magnetic resonance imaging (kMRI).


METHODS
Weight-bearing, multiposition kMRI was performed on symptomatic patients through a full range of flexion-extension. A total of 52 study patients were selected based on the C2-C7 Cobb angle of sagittal alignment: lordotic (from 30 to 45 degrees). We evaluated dynamic changes in different parameters from flexion-extension: spinal canal diameter (CD), spinal cord diameter (SCD), space available for the cord, anterior space available for the cord (ASAC), posterior space available for the cord (PSAC), average distance between the anterior canal and the cord (d-value), and global angle for the spinal canal and cord.


RESULTS
The CD tended to decrease from flexion to extension from C3/C4 to C6/C7, however, there were no significant differences at the proximal and distal levels, C2/C3 and C7/T1. There were no significant differences of SCD between different postures. The SCD tended to decrease from C2/C3 to C7/T1. The ASAC followed the same pattern as CD-values. The ASAC was narrowest at C4/C5 and C5/C6. The PSAC tended to increase from C2/C3 to C7/T1. The spinal cord shifted anteriorly with extension and posteriorly with flexion. In addition, the spinal cord maintained its curve with the movement.


CONCLUSIONS
The kinematics of spinal cord motion may be associated with the pathogenesis of cervical spondylotic myelopathy. However, the spinal cord maintains its curve with position changes. Consequently, different motions of the cervical spine may affect spinal cord migration and cause changes in ASAC and PSAC.
*Orthopedic Department, Wuhan General Hospital of Guangzhou Military Area Command, Wuhan, China †Department of Orthopaedic Surgery, University of Nevada, Las Vegas, NV ‡Department of Orthopaedic Surgery, University of California, Los Angeles §Department of General Surgery, University of California, Irvine, CA ∥Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand ¶Department of Orthopaedic Surgery, Houston Methodist Hospital, Houston, TX #Department of Orthopaedic Surgery, University of Southern California, Los Angeles, CA.
Chengjie
C
Xiong
Michael D
MD
Daubs
Trevor P
TP
Scott
Kevin H
KH
Phan
Akinobu
A
Suzuki
Monchai
M
Ruangchainikom
Allison K
AK
Roe
Bayan
B
Aghdasi
Yanlin
Y
Tan
Jeffrey C
JC
Wang
D000328:Adult; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007700:Kinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009038:Motion; D011187:Posture