Effect Of6Hz Primed Low-frequency Repetitive Transcranial Magnetic Stimulation On The Recovery Of Motor Function In The Patients With Cerebral Infarction

Background and ObjectiveStroke is a common, serious, and disabling global health-care problem.Recovery of motor function following stroke is usually incompleteparticularly in older stroke survivors, which is especially problematic givenits impact on activities of daily living, recovery of motor function remains aclinical challenge in stroke rehabilitation，novel treatment strategies toextend motor rehabilitation after stroke are needed.Transcranial magnetic stimulation (TMS) is a noninvasive and painlessprocedure that uses magnetic fields to create electric currents in local brainareas, thus modulate cortical excitability of motor areas and enhance corticalreorganization. Repetitive TMS (rTMS) applied to the brain can influenceneural excitability of local brain areas and remote brain regions by usingrepeated pulses, with the effect depending mostly on the stimulation frequency. Several trials have shown that low-frequency rTMS applied to thecontralesional hemisphere can significantly improve motor functionrecovery in post-stroke patients. According to the model of interhemisphericcompetition, it is speculated that low-frequency rTMS to the contralesionalhemisphere suppresses local neural activities, reduces interhemisphericinhibition towards the ipsilesional hemisphere, leading to facilitation ofbeneficial functional reorganization in the ipsilesional hemisphere.A recent study explored rTMS effects with and without6Hz primedrTMS on healthy volunteers, which has been shown that the depressanteffects of low-frequency rTMS can be increased and prolonged by precedingit with6Hz primed stimulation. So far, its beneficial effect on motorrecovery in the patients with acute cerebral infarction has not been reported.The purpose of this study is to investigate the effect of6Hz primedlow-frequency rTMS on the recovery of motor function in the patients withacute cerebral infarction.MethodsIn this randomized，single-blinded，sham-controlled trial，a total ofsixty-five patients with acute cerebral infarction and with hemiparalysiswere recruited，and divided into three group：priming rTMS group（realpriming rTMS+real low-frequency rTMS）（n=21），low-frequency rTMSgroup（sham priming rTMS+real low-frequency rTMS）（n=22），and shamrTMS group （sham priming rTMS+sham low-frequency rTMS） （n=22）.Patients from the priming rTMS group received6-Hz primedlow-frequency rTMS(consist of10-min6-Hz priming stimulation followedby20-min low-frequency rTMS of1-Hz)applied to the contralesionalhemisphere.After rTMS，each patient underwent motor training. Outcomes，including NIHSS score，Barthel Index，Fugl-Meyer Assessment（FMA），motor-evoked potential（MEP）latency period，the amplitude of MEP andcentral motor conduction time（CMCT），were assessed before and after tenand forty days of the treatment.ResultsAll patients completed the10-day protocol. The scores of NIHSS，BI，FMA and the MEP latency period，the amplitude of MEP and CMCT had nostatistical significance in the three groups before treatment（P>0.05）.Aftertreatment， the clinical function scores of the three groups improvedsignificantly（P<0.01）.And motor function of the priming rTMS group wassignificantly improved than that of the other two group（sP<0.01）.The motorfunction of the low-frequency rTMS group was also improved significantlythan that of sham rTMS group （P<0.01）。 The value of neuralelectrophysiological indices of the three groups after treatment gotimprovement.The MEP latency period of priming and low-frequency rTMSgroups was significantly shorter than that before treatment（P<0.01）.Theamplitude of MEP and CMCT of priming rTMS group and low-frequencyrTMS group were improved significantly（P<0.01or P<0.05）.The beneficial effect of the protocol on motor function and neural electrophysiologicalindices was almost maintained until one month after treatment.Conclusions1. Low-frequency rTMS can improve clinical neurological scaleratings and neural electrophysiological indices，and enhance motor functionrecovery in patients with cerebral infarction.2. Effect of6Hz primed low-frequency rTMS on motor recovery inpatients with cerebral infarction is more efficacious.