Evaluation of Relationships between Corticospinal Excitability and Somatosensory Deficits in the Acute and Subacute Phases of Stroke

Abstract

Background: Somatosensory deficits are common symptoms post stroke. Repetitive transcranial magnetic stimulation (rTMS) over the motor cortex is able to promote motor rehabilitation, whereby its impact on somatosensory functioning remains unknown. This study was designed to evaluate the association between somatosensory deficits and corticospinal excitability following stroke, with the purpose to provide insights on rTMS interventions for the management of somatosensory deficits.

Methods: Somatosensory functioning and corticospinal excitability (motor-evoked potential, MEP; cortical silence period, CSP) were evaluated from a group of sixteen patients with unilateral ischemic stroke in the acute or subacute phase.

Results: Results indicated that the uncommon presentation of larger MEPs in ipsilesional vs. contralesional motor cortex was associated with worse somatosensory function compared to those with a smaller MEP in ipsilesional motor cortex. Moreover, increased MEP ratio (ipsilesional vs. contralesional motor cortex) was associated with better somatosensory function in patients with well-preserved somatosensory function.

Conclusions: In well-recovered patients, an increased MEP ratio between the ipsilesional and contralesional motor cortex could be an indicator of improved somatosensory functioning following stroke.

Keywords: CSP; MEP; TMS; somatosensory deficits; stroke.