Segmental differences of cervical spinal cord motion: advancing from confounders to a diagnostic tool

M Hupp,C Brockmann,J Rosner,A Curt,P Freund,S Huwyler,R Sutter,K Vallotton,M Klarhoefer,M Farshad

doi:10.1038/s41598-019-43908-x

M Hupp, C Brockmann + Show 8 more

Open Access

https://doi.org/10.1038/s41598-019-43908-x

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Abstract

Increased cranio-caudal spinal cord motion is associated with clinical impairment in degenerative cervical myelopathy. However, whether spinal cord motion holds potential as a neuroimaging biomarker requires further validation. Different confounders (i.e. subject characteristics, methodological problems such as phase drift, etc.) on spinal cord motion readouts have to be considered. Twenty-two healthy subjects underwent phase contrast MRI, a subset of subjects (N = 9) had repeated scans. Parameters of interest included amplitude of velocity signal, maximum cranial respectively maximum caudal velocity, displacement (=area under curve of the velocity signal). The cervical spinal cord showed pulse synchronic oscillatory motions with significant differences in all readouts across cervical segments, with a maximum at C5. The Inter-rater reliability was excellent for all readouts. The test-retest reliability was excellent for all parameters at C2 to C6, but not for maximum cranial velocity at C6 and all readouts at C7. Spinal cord motion was correlated with spinal canal size, heart rate and body size. This is the first study to propose a standardized MRI measurement of spinal cord motion for further clinical implementation based on satisfactory phase drift correction and excellent reliability. Understanding the influence of confounders (e.g. structural conditions of the spine) is essential for introducing cord motion into the diagnostic work up.

Highlights

Oscillatory spinal cord motions were initially shown by intraoperative ultrasound[1]
While measurements of cerebrospinal fluid (CSF) flow have been shown to be less reliable and rather complex at the level of stenosis[7], spinal cord motion appears as an attractive alternative
A reliable and sensitive assessment of cervical spinal cord motions along the cervical spine is required in order to foster its clinical application and potential introduction in the diagnostic work up of degenerative cervical myelopathy (DCM)

Summary

Introduction

Oscillatory spinal cord motions were initially shown by intraoperative ultrasound[1]. In patients with degenerative cervical myelopathy (DCM), several studies applying 2D PC-MRI reported increased spinal cord motion at the level of a cervical spinal stenosis[4,5,6,7]. While measurements of CSF flow have been shown to be less reliable and rather complex (i.e. not easy to implement and run for clinical application) at the level of stenosis[7], spinal cord motion appears as an attractive alternative. The latter is easy to apply and provides parameters that potentially allow to evaluate the extent of cervical dysfunction and could eventually be used to predict the course of DCM. The aim of this study was to investigate cranio-caudal spinal cord motions across the entire cervical spine in healthy volunteers, to evaluate its inter-rater and test-retest reliability for clinical application and its relation to anatomic and biometric conditions

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