Dynamic Cord Compression Causing Cervical Myelopathy

Abstract

Due to the highly mobile nature of the cervical spine, and the fact that most magnetic resonance imagings (MRIs) and computed tomography scans are obtained only in one single position, dynamic cord compression can be an elusive diagnosis that is often missed and not well-understood. In this context, dynamic MRI (dMRI) has been utilized to improve the diagnostic accuracy of cervical stenosis. We performed a literature review on dynamic cord compression in the context of cervical spondylotic myelopathy (CSM), with particular emphasis on the role of dMRI. Cadaveric studies report that the spinal cord lengthens in flexion and the spinal canal dimension increases, whereas the spinal cord relaxes and shortens in extension and the spinal canal decreases. These changes may lead to biomechanical stress in the spinal cord with movement, especially in patients with critical cervical stenosis. The majority of the studies using dMRI in CSM reported that this imaging modality is more sensitive at detecting cervical cord compression compared to routine MRIs done in a neutral position, especially with the neck in extension. Dynamic MRI was also useful to diagnose dynamic cervical cord compression after laminectomies in patients with clinical deterioration without evident cord compression on neutral static MRI. Finally, dMRI is more sensitive in detecting stenosis in patients with CSM than in those with ossification of the posterior longitudinal ligament (OPLL), likely because OPLL patients often have a more limited range of motion than CSM patients. Thus, dMRI is a promising new tool that can help spine surgeons in diagnosing and treating CSM.

Degenerative Cervical Myelopathy: An Overview

“…However, the sample size was small which may have affected the generalisability of the findings. The findings of Breig et al [ 24 ] have been supported in vivo by dynamic MRI studies in patients with DCM [ 25 , 26 ]. These studies are valuable as they explored the effect of dynamic movement on the spinal cord.…”

“…These changes can put biomechanical stress on the spinal cord and its blood supply, leading to compression and ischaemia. If combined with a stenotic cervical spinal canal the patient is at an increased risk of cord compression due to biomechanical stress [ 25 ]. Other dynamic factors include a large cervical range of motion, segmental instability, and spondylolisthesis.…”

“…Dynamic MRI can be more sensitive than static MRI; however, the technique for dynamic MRI is not yet standardised which may lead to confounding factors in studies. The technique also requires specialised equipment and knowledge [ 25 , 26 ].…”

Magnetic Resonance Imaging Grading Systems for Central Canal and Neural Foraminal Stenoses of the Lumbar and Cervical Spines With a Focus on the Lee Grading System

“…Such cases of severe central canal stenosis (grade 3) are occasionally encountered in dynamic compression setting ( Fig. 6 ) [ 38 ].…”

Surgical Strategies and Perioperative Considerations for Cervical Deformity With Cerebral Palsy: A Comprehensive Review of the Literature

“…The excessive involuntary movements in CP cause early degenerative changes (degenerative discs, herniated intervertebral discs, osteophytes) as well as spinal instability [ 6 , 7 ]. Accelerated degeneration and continuous motion in the cervical spine eventually result in CM, which can further complicate a patient’s already compromised neurological function and severely limit their autonomy [ 1 , 8 - 11 ]. In addition, static anatomical factors (i.e., bones or ligaments) can result in problems with stenosis, and dynamic factors (i.e., nerves or muscles) are related to problems of incoordination [ 6 , 10 , 12 - 16 ].…”