In cervical spondylotic myelopathy spinal cord motion is focally increased at the level of stenosis: a controlled cross-sectional study.

STUDY
DESIGN: Level-, age-, and gender-matched controlled cross-sectional cohort study.
OBJECTIVES: To investigate alterations of spinal cord (SC) motion within cervical spondylotic myelopathy (CSM) across the cervical spinal segments and its relation to cerebrospinal fluid (CSF)-flow, anatomic conditions, and clinical parameters.
SETTING: University Hospital Balgrist, Zurich, Switzerland.
METHODS: Overall, 12 patients suffering from CSM at level C5 and 12 controls underwent cardiac-gated 2D phase-contrast-MRI at level C2 and C5 and standard MRI sequences. Parameters of interest: Velocity measurements of SC and CSF (area under the curve = total displacement (normalization for duration of the heart cycle), total displacement ratio (C5/C2; intraindividual normalization for confounders)), spinal canal diameters, clinical motor- and sensory scores, and performance measures.
RESULTS: Interrater reliability was excellent for SC motion at both levels and for CSF flow at C2, but not reliable for CSF flow at C5. Within controls, SC motion at C2 positively correlated with SC motion at C5 (p = 0.000); this correlation diminished in patients (p = 0.860). SC total displacement ratio was significantly increased in patients (p = 0.029) and correlated with clinical impairment (p = 0.017). Morphometric measures of the extent of stenosis were not related to SC motion or clinical symptoms.
CONCLUSION: The findings revealed physiological interactions of CSF flow and SC motion across the cervical spine in healthy controls while being diminished in CSM patients. Findings of focally increased SC motion at the level of stenosis were related to clinical impairment and might be promising as a diagnostic and prognostic marker in CSM. SPONSORSHIP: CRPP Neurorehab of the University of Zurich, Switzerland.