Onset Latency of Motor Evoked Potentials in Motor Cortical Mapping with Neuronavigated Transcranial Magnetic Stimulation.

Content Provider	Europe PMC
Author	Kallioniemi, Elisa Pitkänen, Minna Säisänen, Laura Julkunen, Petro
Copyright Year	2015
Description	Cortical motor mapping in pre-surgical applications can be performed using motor evoked potential (MEP) amplitudes evoked with neuronavigated transcranial magnetic stimulation. The MEP latency, which is a more stable parameter than the MEP amplitude, has not so far been utilized in motor mapping. The latency, however, may provide information about the stress in damaged motor pathways, e.g. compression by tumors, which cannot be observed from the MEP amplitudes. Thus, inclusion of this parameter could add valuable information to the presently used technique of MEP amplitude mapping. In this study, the functional cortical representations of first dorsal interosseous (FDI), abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles were mapped in both hemispheres of ten healthy righthanded volunteers. The cortical muscle representations were evaluated by the area and centre of gravity (CoG) by using MEP amplitudes and latencies. As expected, the latency and amplitude CoGs were congruent and were located in the centre of the maps but in a few subjects, instead of a single centre, several loci with short latencies were observed. In conclusion, MEP latencies may be useful in distinguishing the cortical representation areas with the most direct pathways from those pathways with prolonged latencies. However, the potential of latency mapping to identify stressed motor tract connections at the subcortical level will need to be verified in future studies with patients.
Abstract	Cortical motor mapping in pre-surgical applications can be performed using motor evoked potential (MEP)amplitudes evoked with neuronavigated transcranial magnetic stimulation. The MEP latency, which is a more stableparameter than the MEP amplitude, has not so far been utilized in motor mapping. The latency, however, may provideinformation about the stress in damaged motor pathways, e.g. compression by tumors, which cannot be observed from theMEP amplitudes. Thus, inclusion of this parameter could add valuable information to the presently used technique ofMEP amplitude mapping. In this study, the functional cortical representations of first dorsal interosseous (FDI), abductorpollicis brevis (APB) and abductor digiti minimi (ADM) muscles were mapped in both hemispheres of ten healthy righthandedvolunteers. The cortical muscle representations were evaluated by the area and centre of gravity (CoG) by usingMEP amplitudes and latencies. As expected, the latency and amplitude CoGs were congruent and were located in thecentre of the maps but in a few subjects, instead of a single centre, several loci with short latencies were observed. Inconclusion, MEP latencies may be useful in distinguishing the cortical representation areas with the most direct pathwaysfrom those pathways with prolonged latencies. However, the potential of latency mapping to identify stressed motor tractconnections at the subcortical level will need to be verified in future studies with patients.
Related Links	https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC4627389&blobtype=pdf
Volume Number	9
PubMed Central reference number	PMC4627389
PubMed reference number	26535068
Journal	The Open Neurology Journal [Open Neurol J]
e-ISSN	1874205X
DOI	10.2174/1874205x01509010062
Language	English
Publisher	Bentham Open
Publisher Date	2015-07-31
Access Restriction	Open
Rights License	This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited. © Kallioniemi et al.; Licensee Bentham Open.
Subject Keyword	Latency Motor evoked potential Motor mapping Neuronavigated transcranial magnetic stimulation Pre-surgical
Content Type	Text
Resource Type	Article
Subject	Psychiatry and Mental Health Neurology Neurology (clinical)