Impact of coil position and electrophysiological monitoring on determination of motor thresholds to transcranial magnetic stimulation

Conforto, Adriana Bastos; Z'Graggen, Werner J; Kohl, Alexandra S; Rösler, Kai M; Kaelin-Lang, Alain (2004). Impact of coil position and electrophysiological monitoring on determination of motor thresholds to transcranial magnetic stimulation. Clinical neurophysiology, 115(4), pp. 812-9. Amsterdam: Elsevier 10.1016/j.clinph.2003.11.010

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OBJECTIVE: We compared motor and movement thresholds to transcranial magnetic stimulation (TMS) in healthy subjects and investigated the effect of different coil positions on thresholds and MEP (motor-evoked potential) amplitudes. METHODS: The abductor pollicis brevis (APB) 'hot spot' and a standard scalp position were stimulated. APB resting motor threshold (APB MEP-MT) defined by the '5/10' electrophysiological method was compared with movement threshold (MOV-MT), defined by visualization of movements. Additionally, APB MEP-MTs were evaluated with the '3/6 method,' and MEPs were recorded at a stimulation intensity of 120% APB MEP-MT at each position. RESULTS: APB MEP-MTs were significantly lower by stimulation of the 'hot spot' than of the standard position, and significantly lower than MOV-MTs (n=15). There were no significant differences between the '3/6' and the '5/10' methods, or between APB MEP amplitudes by stimulating each position at 120% APB MEP-MT. CONCLUSIONS: Coil position and electrophysiological monitoring influenced motor threshold determinations. Performing 6 instead of 10 trials did not produce different threshold measurements. Adjustment of intensity according to APB MEP-MT at the stimulated position did not influence APB MEP amplitudes. SIGNIFICANCE: Standardization of stimulation positions, nomenclature and criteria for threshold measurements should be considered in design and comparison of TMS protocols.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology
UniBE Contributor:	Kaelin, Alain, Z'Graggen, Werner Josef, Rösler, Kai Michael
ISSN:	1388-2457
ISBN:	15003761
Publisher:	Elsevier
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 15:05
Last Modified:	05 Dec 2022 14:20
Publisher DOI:	10.1016/j.clinph.2003.11.010
PubMed ID:	15003761
Web of Science ID:	000220414800012
URI:	https://boris.unibe.ch/id/eprint/28447 (FactScience: 120815)