title: Interhemispheric asymmetry of corticomotor excitability after chronic cerebellar infarcts.
abstract: Early after stroke, there is loss of intracortical facilitation (ICF) and increase in short-interval intracortical inhibition (SICI) in the primary motor cortex (M1) contralateral to a cerebellar infarct. Our goal was to investigate intracortical M1 function in the chronic stage following cerebellar infarcts (>4 months). We measured resting motor threshold (rMT), SICI, ICF, and ratios between motor-evoked potential amplitudes (MEP) and supramaximal M response amplitudes (MEP/M; %), after transcranial magnetic stimulation was applied to the M1 contralateral (M1(contralesional)) and ipsilateral (M1(ipsilesional)) to the cerebellar infarct in patients and to both M1s of healthy age-matched volunteers. SICI was decreased in M1(contralesional) compared to M1(ipsilesional) in the patient group in the absence of side-to-side differences in controls. There were no significant interhemispheric or between-group differences in rMT, ICF, or MEP/M (%). Our results document disinhibition of M1(contralesional) in the chronic phase after cerebellar stroke.
authors.affiliation: Department of Neurology, Clinics Hospital/São Paulo University, São Paulo, Brazil. suzetefarias@terra.com.br
authors.forename: Suzete Nascimento
authors.initials: SN
authors.lastname: Farias da Guarda
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Cohen
authors.forename: Marco
authors.initials: M
authors.lastname: da Cunha Pinho
authors.forename: Fábio Iuji
authors.initials: FI
authors.lastname: Yamamoto
authors.forename: Paulo Eurípedes
authors.initials: PE
authors.lastname: Marchiori
authors.forename: Milberto
authors.initials: M
authors.lastname: Scaff
authors.forename: Adriana Bastos
authors.initials: AB
authors.lastname: Conforto
mesh_terms: D000328:Adult; D020520:Brain Infarction / Q000503:physiopathology*; D002526:Cerebellar Diseases / Q000503:physiopathology*; D019054:Evoked Potentials, Motor; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D020521:Stroke / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
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