Increase in Short-Interval Intracortical Facilitation of the Motor Cortex after Low-Frequency Repetitive Magnetic Stimulation of the Unaffected Hemisphere in the Subacute Phase after Stroke

Abstract EN

Low-frequency repetitive transcranial magnetic stimulation of the unaffected hemisphere (UH-LF-rTMS) in patients with stroke can decrease interhemispheric inhibition from the unaffected to the affected hemisphere and improve hand dexterity and strength of the paretic hand.

The objective of this proof-of-principle study was to explore, for the first time, effects of UH-LF-rTMS as add-on therapy to motor rehabilitation on short-term intracortical inhibition (SICI) and intracortical facilitation (ICF) of the motor cortex of the unaffected hemisphere ( M 1 UH ) in patients with ischemic stroke.

Eighteen patients were randomized to receive, immediately before rehabilitation treatment, either active or sham UH-LF-rTMS, during two weeks.

Resting motor threshold (rMT), SICI, and ICF were measured in M 1 UH before the first session and after the last session of treatment.

There was a significant increase in ICF in the active group compared to the sham group after treatment, and there was no significant differences in changes in rMT or SICI.

ICF is a measure of intracortical synaptic excitability, with a relative contribution of spinal mechanisms.

ICF is typically upregulated by glutamatergic agonists and downregulated by gabaergic antagonists.

The observed increase in ICF in the active group, in this hypothesis-generating study, may be related to M 1 UH reorganization induced by UH-LF-rTMS.