The Mechanism Of Acupuncture And TDCS On Dysphagia After Stroke On The Cortical Excitability Of Swallowing

Objective: This study aimed to investigate if the EEG Nonlinear dynamics analysis(NDA)could be an objective neural electrophysiological analysis method of the excitability of the swallowing cortex for the patients with dysphagia after stroke,analyze the recovery of dysphagia after stroke and cortical excitability in stroke patients and explore the mechanism.Methods: Part 1: An A-B design was used.In Phase A,sham tDCS was administered;in Phase B,anodal tDCS was administered.Swallowing maneuvers were administered throughout both the phases.Five inpatients with post-stroke swallowing apraxia and six age-matched healthy subjects were included.Swallowing apraxia assessments were measured using Swallowing apraxia scale(SAS)in five inpatients with swallowing apraxia after stroke before Phase A,before Phase B,and after Phase B.The cortical excitability of swallowing were analyzed with the Ap En of EEG NDA under three conditions(resting,reflexive swallowing,and volitional swallowing)for three patients and six healthy subjects before and after Phase B.Part 2: A randomized,controlled trial design was used.Forty patients with dysphagia after stroke were randomly divided into 3 groups: Control group(N=14),tDCS group(N=15),acupuncture group(N=11).The control group received the swallowing maneuvers.The tDCS group received anodal tDCS over bilateral S1M1 of swallowing combined with swallowing maneuvers.The acupuncture group received acupuncture therapy combined with swallowing maneuvers.The scores of Swallow severity scale(SSS)and Modified Mann assessment of swallowing ability(MMASA)were compared between the three groups before and after 1-week and 2-week treatment.The SSS scores were compared between the three groups at 1-month of follow-up.The cortical excitability of swallowing were analyzed with the Ap En of EEG NDA under two conditions(resting and volitional swallowing)for 17 patients with dysphagia after hemispheric stroke,including control group(N=4),tDCS group(N=6)and acupuncture group(N=7).Results:Part 1: No differences in swallowing function scores of SAS were found between PreA and Pre-B for all five patients;however,after Phase B,swallowing apraxia scores increased.EEG Ap En analysis: In the control group,a greater number of regions for control group were activated during the volitional swallowing task than during the reflexive swallowing task.In the 3 patients,before anodal tDCS treatment,the Ap En of central-parietal-temporal regions in the affected hemisphere increased during reflexive swallowing(P<0.01),but the excitability of any monitored regions did not significantly increase during volitional swallowing(P>0.01).However,after anodal tDCS treatment,the Ap En of more regions in the affected or unaffected hemispheres increased during reflexive swallowing and volitional swallowing(P<0.01).Part 2: Swallowing function assessment: there was no significant difference in scores of MMASA and SSS among the control group,tDCS group and acupuncture group before treatment,after 1-week and 2-week treatments(P>0.05).Compared with pretreatment,the scores of MMASA and SSS significantly increased(P<0.05)for control group,tDCS group and acupuncture group after 1-week and 2-week treatments.At the 1-month follow-up,there was no significant difference in scores of SSS among the tDCS group and acupuncture group(P>0.05),and the scores of SSS in tDCS group and acupuncture group were higer than those in control group(P<0.05).EEG Ap En analysis: Compared with the resting condition,the Ap En of the control group,tDCS group and acupuncture group in the unaffected central region(Cu)(0.81±0.05,0.86±0.09 and 0.85 ± 0.10)increased obviously for volitional swallowing task before treatment(P<0.01).After 2-week treatment,compared with the resting condition,the Ap En of the control group in the unaffected partial region(Pu)(0.89±0.12),the Ap En of the tDCS group in the unaffected central region(Cu),unaffected partial region(Pu)and affected central region(Ca)(0.87±0.07,0.82±0.07 and 0.79±0.04),and the Ap En of acupuncture group in the unaffected central region(Cu)and the unaffected frontal region(Fu)(0.80±0.06 and 0.79±0.07)increased obviously for volitional swallowing task(P<0.01).Conclusions:EEG NDA might be an objective analysis method for the changes of cortical excitability correlated with dysphagia after stroke after traditional Chinese and western intervention.Combined with swallowing maneuvers,the acupuncture treatment or tDCS may facilitate the long-term recovery of dysphagia after stroke,and the mechanism could be related to increased cortical excitability of swallowing.