title: Can forearm muscle activity be selectively recorded using conventional surface EMG-electrodes in transcranial magnetic stimulation? A feasibility study.
abstract: OBJECTIVE
  This feasibility study evaluates the effect of varying the position of conventional surface EMG-electrodes on the forearm when using Transcranial Magnetic Stimulation (TMS). The aim was to find optimal bipolar electrode positions for forearm extensor muscles, which would be clinically relevant to predict motor recovery after stroke.
  
  
  METHODS
  In a healthy female subject, three rings of surface EMG-electrodes were placed around the dominant forearm, leading to 200 different electrode pairs. Both peripheral electrical stimulation and TMS were applied at suprathreshold intensities.
  
  
  RESULTS
  With electrical stimulation of the median and radial nerve, similar waveform morphology was found for all electrode pairs, covering both flexors and extensors. Also with TMS, remarkable similarities between all electrode pairs were found, suggesting minimal selectivity. In both peripheral electrical stimulation and TMS, the curves became more irregular with decreasing inter-electrode distances.
  
  
  CONCLUSIONS
  Neither with peripheral electrical stimulation nor with TMS it was possible to selectively record extensor or flexor forearm muscle activity using conventional surface EMG-electrodes.
  
  
  CONCLUSIONS
  Despite this negative result, the important role of the forearm extensor muscles in the prognosis of motor recovery after stroke warrants further research into novel methods for selectively recording muscle activity in TMS other than by conventional surface EMG.
authors.affiliation: Department of Rehabilitation, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: C D
authors.initials: CD
authors.lastname: Bakker
authors.affiliation: Department of Rehabilitation, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands; Libra, Rehabilitation & Audiology, Location Blixembosch, Eindhoven, The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: van Kuijk
authors.affiliation: Department of Rehabilitation, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: A C H
authors.initials: AC
authors.lastname: Geurts
authors.affiliation: Donders Institute for Brain, Cognition & Behaviour, Department of Neurology/Clinical Neurophysiology, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands; Faculty of Human Movement Sciences, MOVE Research Institute, VU University, Amsterdam, The Netherlands. Electronic address: dick.stegeman@radboudumc.nl.
authors.forename: D F
authors.initials: DF
authors.lastname: Stegeman
authors.affiliation: Donders Institute for Brain, Cognition & Behaviour, Department of Neurology/Clinical Neurophysiology, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Pasman
mesh_terms: D000200:Action Potentials / Q000502:physiology; D019540:Area Under Curve; D004558:Electric Stimulation; D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation*; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D005542:Forearm / Q000502:physiology; D006801:Humans; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D011826:Radial Nerve / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000295:instrumentation*
keywords: Artifact; Evoked potentials; Motor; Muscles; Stimulation; Transcranial magnetic; Upper extremity