Priming sensorimotor cortex to enhance task-specific training after subcortical stroke

Abstract

Objective: This double-blind sham-controlled crossover study investigated the interactions between primary sensory and motor cortex after stroke and their response to Theta Burst Stimulation (TBS).

Methods: Thirteen chronic subcortical stroke patients with upper limb impairment performed standardised dexterity training primed with ipsilesional M1 intermittent TBS (iTBSiM1), contralesional M1 continuous TBS (cTBScM1) or sham TBS. The effects on sensorimotor integration, corticomotor excitability, sensation and grip-lift kinetics were examined.

Results: After iTBSiM1, improvements in paretic grip-lift performance were accompanied by an immediate facilitation of ipsilesional M1 excitability and a subsequent increase in ipsilesional short latency afferent inhibition (SAI) during training. Precision grip-lift performance improved after cTBScM1 and training, alongside increased ipsilesional M1 excitability with no effect on ipsilesional SAI. There were no effects on sensory performance.

Conclusion: Primary motor cortex iTBS not only modulates M1 corticospinal excitability but also increases M1 receptiveness to sensory input.

Significance: Priming with iTBSiM1 may enhance ipsilesional sensorimotor integration and facilitate better quality sensorimotor training after subcortical stroke.

Keywords: Sensorimotor integration; Short latency afferent inhibition; Stroke rehabilitation; Theta burst stimulation; Transcranial magnetic stimulation.