title: Longitudinal changes of motor cortical excitability and transcallosal inhibition after subcortical stroke.
abstract: OBJECTIVE
  A general lack of longitudinal studies on interhemispheric interactions following stroke led us to use transcranial magnetic stimulation (TMS) to examine changes in corticospinal/intracortical excitability and transcallosal inhibition over a 1-year period following subcortical stroke.
  
  
  METHODS
  We measured TMS parameters such as motor threshold (MT), short-interval intracortical inhibition (SICI), and ipsilateral silent period (iSP) and evaluated clinical scores at three time-points (T1, T2, and T3) in 24 patients and 25 age-matched healthy subjects.
  
  
  RESULTS
  At T1, we observed reduced MTs and SICIs with prolonged iSPs in the unaffected hemisphere (UH). In contrast, increased MTs and reduced SICIs were observed in the affected hemisphere (AH). These abnormalities gradually reduced and no MEP response to TMS at T1 predicted a worse prognosis. The prolonged iSP at T1 was associated with more severe impairments, but it did not necessarily predict a worse prognosis after 1year.
  
  
  CONCLUSIONS
  UH excitability was increased at the post-acute time-period, which may have resulted in enhanced transcallosal inhibition to the AH. However, it is unclear whether there was a causal relationship between the enhanced transcallosal inhibition and the extent of clinical recovery.
  
  
  CONCLUSIONS
  This is the first study to demonstrate changes in transcallosal inhibition over a longitudinal period following stroke.
authors.affiliation: Department of Neurology, University of Occupational and Environmental Health, School of Medicine, Japan. Electronic address: Utako@med.uoeh-u.ac.jp.
authors.forename: Utako
authors.initials: U
authors.lastname: Takechi
authors.affiliation: Department of Neurology and Rehabilitation Medicine, Kumamoto Kinoh Hospital, Kumamoto, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Matsunaga
authors.affiliation: Department of Neurology and Rehabilitation Medicine, Kumamoto Kinoh Hospital, Kumamoto, Japan.
authors.forename: Ryoji
authors.initials: R
authors.lastname: Nakanishi
authors.affiliation: Department of Neurology and Rehabilitation Medicine, Kumamoto Kinoh Hospital, Kumamoto, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Yamanaga
authors.affiliation: Department of Human and Environmental Informatics, Graduate School of Science and Technology, Kumamoto University, Japan.
authors.forename: Nobuki
authors.initials: N
authors.lastname: Murayama
authors.affiliation: Department of Mental Health, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Mafune
authors.affiliation: Department of Neurology, University of Occupational and Environmental Health, School of Medicine, Japan.
authors.forename: Sadatoshi
authors.initials: S
authors.lastname: Tsuji
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009433:Neural Inhibition / Q000502:physiology*; D011379:Prognosis; D011712:Pyramidal Tracts / Q000503:physiopathology; D020127:Recovery of Function / Q000502:physiology*; D020521:Stroke / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
keywords: Intracortical inhibition; Motor-evoked potential; Stroke; Transcallosal inhibition; Transcranial magnetic stimulation