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Acta Neurochirurgica

, Volume 160, Issue 5, pp 923–932 | Cite as

Longitudinal brain activation changes related to electrophysiological findings in patients with cervical spondylotic myelopathy before and after spinal cord decompression: an fMRI study

  • Lumír Hrabálek
  • Pavel Hok
  • Petr Hluštík
  • Eva Čecháková
  • Tomáš Wanek
  • Pavel Otruba
  • Miroslav Vaverka
  • Petr Kaňovský
Original Article - Spine

Abstract

Background

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction, potentially leading to severe disability. Abnormal cervical spine magnetic resonance imaging (MRI) and motor evoked potentials (MEPs) are independent predictors of disease progression. Abnormal MRI is accompanied by various activation changes in functional brain MRI (fMRI), whereas preoperative and postoperative fMRI adaptations associated with abnormal preoperative MEP remain unknown.

Methods

Twenty patients (9 males, average age 56.6) with evidence of spinal cord compression on MRI and clinical signs of mild CSM were included. Participants were classified according to their preoperative MEP and underwent three brain fMRI examinations: before surgery, 6, and 12 months after surgery while performing repeated extension-flexion of each wrist.

Results

Functional MRI activation was compared between two subsets of patients, with normal and clearly abnormal MEP (right wrist: 8 vs. 8; left wrist: 7 vs. 9). At baseline, abnormal MEPs were associated with hyperactivation in the cerebellum. At the first follow-up, further hyperactivations emerged in the contralateral sensorimotor cortices and persisted for 1 year. In normal baseline MEP, activation mostly decreased in the ipsilateral sensorimotor cortex postoperatively. The ipsilateral sensorimotor activation after 1-year follow-up correlated with baseline MEP.

Conclusions

Abnormal corticospinal MEP findings in cervical spondylotic myelopathy were associated with differences in brain activation, which further increased after spinal cord decompression and did not resolve within 12-month follow-up. In summary, surgery may come too late for those patients with abnormal MEP to recover completely despite their mild clinical signs and symptoms.

Keywords

Cervical spondylotic myelopathy Functional magnetic resonance imaging Motor evoked potentials Sensorimotor system Corticospinal tract 

Abbreviations

AP

anteroposterior

ANOVA

analysis of variance

CMCT

central motor conduction time

CSM

cervical spondylotic myelopathy

DWI

diffusion-weighted imaging

EPI

echo planar imaging

fMRI

functional MR imaging

FWHM

full width at half maximum

GLM

general linear model

Group A

abnormal MEP

Group B

borderline MEP

Group N

normal MEP

LE

lower extremity

LW

left wrist

M0

month 0

M6

month 6

M12

month 12

MEP

motor evoked potentials

mJOA

modified Japanese Orthopaedic Association score

MNI

Montreal Neurological Institute

MPRAGE

magnetization prepared rapid acquisition gradient echo

MRI

magnetic resonance imaging

NDI

Neck Disability Index

PEEK

polyetheretherketon

ROI

region of interest

RW

right wrist

SD

standard deviation

SEP

somatosensory evoked potentials

SMA

supplementary motor area

UE

upper extremity

VAS

visual analogue scale

Notes

Acknowledgements

This study was supported by the grant IGA MZ ČR NT 14609.

Funding

This study was supported by the grant IGA MZ ČR NT 14609.

Compliance with ethical standards

Prior to study initiation, the study protocol was approved by the institutional ethics committee. Informed consent was obtained from each study participant prior to any study procedure.

Conflicts of interest

All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Animal experiments

This article does not contain any studies with animals performed by any of the authors.

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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of NeurosurgeryPalacký University Olomouc and University Hospital OlomoucOlomoucCzech Republic
  2. 2.Department of NeurologyPalacký University Olomouc and University Hospital OlomoucOlomoucCzech Republic
  3. 3.Department of RadiologyPalacký University Olomouc and University Hospital OlomoucOlomoucCzech Republic

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