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

• The effects of Theta Burst Stimulation (TBS)-primed dexterity training on sensorimotor integration, corticomotor excitability, sensation and grip-lift kinetics were examined in chronic subcortical stroke patients.
• Intermittent TBS (iTBS) of ipsilesional primary motor cortex (M1) modulated corticomotor excitability and increased M1 receptiveness to sensory input.
• Priming ipsilesional M1 with iTBS prior to upper limb therapy may facilitate sensorimotor integration and serve as a useful adjunct to improve the quality of sensorimotor training during rehabilitation after subcortical stroke.

ObjectiveThis 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).MethodsThirteen 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.ResultsAfter 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.ConclusionPrimary motor cortex iTBS not only modulates M1 corticospinal excitability but also increases M1 receptiveness to sensory input.SignificancePriming with iTBSiM1 may enhance ipsilesional sensorimotor integration and facilitate better quality sensorimotor training after subcortical stroke.