Interhemispheric Asymmetry of Corticomotor Excitability After Chronic Cerebellar Infarcts
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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 (M1contralesional) and ipsilateral (M1ipsilesional) to the cerebellar infarct in patients and to both M1s of healthy age-matched volunteers. SICI was decreased in M1contralesional compared to M1ipsilesional 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 M1contralesional in the chronic phase after cerebellar stroke.
KeywordsTranscranial magnetic stimulation Paired pulse Cerebellar disease Stroke
Dr. Suzete N. Farias received a research scholarship from Fundação Faculdade de Medicina, Clinics Hospital/São Paulo University. We thank Michael Dimyan for helpful comments and suggestions.
Conflict of Interest
The authors have no conflicts of interest.
- 7.Timmann D, Drepper J, Frings M, Maschke M, Richter S, Gerwig M, et al. The human cerebellum contributes to motor, emotional and cognitive associative learning. A review, Cortex 2009, doi: 10.1016/j.cortex.2009.06.009
- 9.Kujirai T, Caramia MD, Rothwell JC, Day BL, Thompson PD, Ferbert A, et al. Corticortical inhibition in human motor cortex. J Physiol(Lond). 1993;471:501–19.Google Scholar
- 11.Cicinelli P, Traversa R, Oliveri M, Palmieri MG, Filippi MM, Pasqualetti P, et al. Intracortical excitatory and inhibitory phenomena to paired transcranial magnetic stimulation in healthy human subjects: differences between the right and left hemisphere. Neurosci Lett. 2000;288:171–4.CrossRefPubMedGoogle Scholar