Interhemispheric asymmetry of corticomotor excitability after chronic cerebellar infarcts

Cerebellum. 2010 Sep;9(3):398-404. doi: 10.1007/s12311-010-0176-7.

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.

MeSH terms

  • Adult
  • Brain Infarction / physiopathology*
  • Cerebellar Diseases / physiopathology*
  • Evoked Potentials, Motor
  • Female
  • Functional Laterality / physiology*
  • Humans
  • Male
  • Middle Aged
  • Motor Cortex / physiopathology*
  • Stroke / physiopathology*
  • Transcranial Magnetic Stimulation
  • Young Adult