Short interval intracortical inhibition: Variability of amplitude and threshold-tracking measurements with 6 or 10 stimuli per point

Hatice Tankisi; Bülent Cengiz; Gintaute Samusyte; James Howells; Martin Koltzenburg; Hugh Bostock

doi:10.1016/j.neucli.2021.11.006

Short interval intracortical inhibition: Variability of amplitude and threshold-tracking measurements with 6 or 10 stimuli per point

Neurophysiol Clin. 2022 Apr;52(2):170-173. doi: 10.1016/j.neucli.2021.11.006. Epub 2022 Jan 6.

Authors

Hatice Tankisi¹, Bülent Cengiz², Gintaute Samusyte³, James Howells⁴, Martin Koltzenburg⁵, Hugh Bostock⁶

Affiliations

¹ Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
² Department of Neurology, Gazi University Faculty of Medicine, Beşevler, 06500 Ankara, Turkey.
³ Department of Neurology, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania.
⁴ Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia.
⁵ Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG London, United Kingdom; Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, Queen Square, WC1N 3BG London, United Kingdom.
⁶ Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG London, United Kingdom. Electronic address: [email protected].

PMID: 35000804
DOI: 10.1016/j.neucli.2021.11.006

Abstract

Reduced short-interval intracortical inhibition (SICI) in motor neuron disease has been demonstrated by amplitude changes (A-SICI) and threshold-tracking (T-SICI) using 10 stimuli per inter-stimulus interval (ISI). To test whether fewer stimuli would suffice, A-SICI and T-SICI were recorded twice from 30 healthy subjects using 6 and 10 stimuli per ISI. Using fewer stimuli increased mean A-SICI variances by 23.8% but the 7.3% increase in T-SICI variance was not significant. We conclude that our new parallel threshold-tracking SICI protocol, with 6 stimuli per ISI, can reduce time and stimulus numbers by 40% without appreciable loss of accuracy.

Keywords: Parallel threshold-tracking versus conventional TMS; SICI variability; Short-interval intracortical inhibition.

MeSH terms

Electromyography / methods
Evoked Potentials, Motor* / physiology
Humans
Motor Cortex* / physiology
Neural Inhibition / physiology
Transcranial Magnetic Stimulation / methods

Grants and funding

MR/K015222/1/MRC_/Medical Research Council/United Kingdom