The use of electronic coil location control for focal magnetic stimulation at the cervical level

Andrey Rodionov; Aleksandra Tolmacheva; Erika Kirveskari; Jyrki P Mäkelä; Anastasia Shulga

doi:10.1016/j.jneumeth.2019.108444

The use of electronic coil location control for focal magnetic stimulation at the cervical level

J Neurosci Methods. 2019 Dec 1:328:108444. doi: 10.1016/j.jneumeth.2019.108444. Epub 2019 Sep 28.

Authors

Andrey Rodionov¹, Aleksandra Tolmacheva², Erika Kirveskari³, Jyrki P Mäkelä⁴, Anastasia Shulga⁵

Affiliations

¹ BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029, Helsinki, Finland. Electronic address: andrey.rodionov@helsinki.fi.
² BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029, Helsinki, Finland. Electronic address: aleksandra.zubareva@helsinki.fi.
³ BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029, Helsinki, Finland; Clinical Neurosciences, Clinical Neurophysiology, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029, Helsinki, Finland. Electronic address: erika.haaksiluoto@hus.fi.
⁴ BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029, Helsinki, Finland. Electronic address: jyrki.makela@hus.fi.
⁵ BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029, Helsinki, Finland; Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, P.O. Box 372, FI-00029, Helsinki, Finland. Electronic address: anastasia.shulga@helsinki.fi.

PMID: 31574289
DOI: 10.1016/j.jneumeth.2019.108444

Abstract

Background: Accurate re-positioning of the coil is challenging in magnetic stimulation at the cervical spinal level. The applicability of coil location control for this type of stimulation is unexplored.

New method: Utilizing a figure-of-eight coil and anatomy-specific models of the magnetic stimulation system, we developed a novel technique that enables probing corticospinal excitability at the cervical spinal level. Magnetic stimulation was performed in 9 healthy subjects at C2-C6 spinal levels using a figure-of-eight coil and a coil tracking system. MEPs were recorded from the abductor digiti minimi muscle. The functioning of the coil tracking system was tested with an estimated electric field maximum (eEFM) above the C1 cervical level (group 1) and below (group 2). Motor-evoked potential (MEP) reproducibility was assessed with intra-class correlation coefficient (ICC).

Results: The use of coil location control in cervical level focal magnetic stimulation enabled the recording of highly reproducible MEPs. Within one co-registration, the ICC 95% confidence interval (CI) in group 1 was 0.89-0.99 and in group 2 was 0.24-0.85.

Comparison with existing methods and conclusions: This method can be used for accurate maintenance and retrieval of the focal coil position at the cervical level with low spatial variability during stimulation. Existing methodologies employ determination of the coil location based on external landmarks, which makes the procedure cumbersome. This technique can optimize existing stimulation protocols and facilitate development of navigated spinal stimulation.

Keywords: Cervical spine; Coil location control; Figure-of-eight coil; Magnetic stimulation; Motor-evoked potential; Reproducibility.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Cervical Cord* / physiology
Electromyography
Evoked Potentials, Motor* / physiology
Female
Humans
Magnetic Resonance Imaging
Male
Muscle, Skeletal* / physiology
Physical Stimulation
Transcranial Magnetic Stimulation / methods*