Comparison of Tongue Acupuncture and Traditional Acupuncture in the Treatment of Poststroke Dysarthria: A Meta-Analysis and Tongue Acupuncture System Classification Evaluation

Objective To discuss whether tongue acupuncture is more effective than traditional acupuncture in the treatment of poststroke dysarthria and explore the advantage of tongue acupuncture treatment parameters. Methods We evaluated the efficacy of tongue acupuncture compared with traditional acupuncture through a rigorous meta-analysis process. The included studies were from eight databases in English and Chinese. The Cochrane risk of bias assessment tool was used to evaluate the quality of studies. Stata15.1 software was used for meta-analysis and sensitivity analysis. Tongue acupuncture therapeutic parameters were classified and counted based on tongue acupoint location, acupuncture manipulation, and the number of manipulations. Subgroup analysis was used to compare the differences between various treatment parameters. Outcome The meta-analysis eventually included a total of 9 studies. Tongue acupuncture is superior to traditional acupuncture in clinical efficacy [OR = 3.62, 95%Cl (2.24, 5.85), P < 0.0001], FDA score [SMD = −1.99, 95%Cl (−3.77, −0.21), P=0.028], and NIHSS score [WMD = 0.86, 95%Cl (0.15, 1.57), P=0.017, I2 = 31.7%] in the treatment of poststroke dysarthria. According to the classified statistics of tongue acupuncture treatment parameters, there are three kinds of tongue acupuncture points in 9 studies: lingual surface, sublingual, and both lingual surface and sublingual acupoints. The operation methods include the oblique stabbing of the root of the tongue, twisting after stabbing, and acupoint pricking. The number of operation methods varies from 1 to 3. Conclusion Tongue acupuncture outperforms traditional acupuncture in terms of clinical efficacy, FDA score, and NIHSS score in the treatment of poststroke dysarthria. The curative effect of sublingual acupoints is better than that of lingual surface acupoints, the combined use of multiple manipulations is better than that of a single manipulation, and acupuncture manipulation has a cumulative effect. PROSPERO registration number: CRD42021285722.


Introduction
Dysarthria, also known as dyskinesia dysarthria, is a speech disease characterized by muscular paralysis and dyskinesia of the articulatory organs caused by lesions of the central, peripheral nervous system, or the muscle itself. It is one of the common complications of a stroke [1]. Te main symptoms of dysarthria patients include unclear speech, long tone, dysrhythmic control of speech speed, monotonous language, and silence. It is often accompanied by dysphagia, increased sputum and salivation, and other symptoms [2]. About 20%-30% of stroke patients will experience dysarthria, and most of them will have psychological obstacles [3]. It is vital to carry out rehabilitation treatments for dysarthria patients.
Speech training is the main treatment for postapoplectic dysarthria [4,5]. Breathing and rhythm training, articulation training, and training to overcome nasal breath and laborious sounds are all part of speech training [6]. Other treatment methods include acupuncture remedy [7,8], massage manipulation therapy, pronunciation EMG stimulation therapy, hyperbaric oxygen therapy (HPO), and training of articulatory organs.
In China's domestic research during the last ten years, clinical trials of acupuncture in the treatment of dysarthria after stroke have yielded favorable curative efects. Te therapeutic acupoints REN23 and GB20 are distributed in the glossopharyngeal, sublingual, and vagal innervation areas. Acupuncture can improve nerve sensitivity and promote the recovery of motor function. In recent years, studies have frequently reported on the comparison of curative efects between diferent acupuncture points to explore better acupoint selection methods. Tongue acupuncture in the treatment of dysarthria is a new method of acupoint selection that improves the original traditional acupoint selection method by increasing the number of tongue points and manipulation. Acupuncture on the tongue can increase central nervous system excitability and activate the functional activity of the language area of the brain.
Previous studies have proved that electroacupuncture combined with language training and manipulation is better than simple language training [7]. Te results of its subgroup analysis of manipulation types suggested that there was no signifcant diference between diferent manipulations. Trough this meta-analysis, we intend to provide evidence that the curative efect of tongue acupuncture is better than traditional acupuncture and to judge whether diferent acupoint prescriptions have relevant efects on the curative efect, so as to provide future direction of acupuncture for clinical in poststroke dysarthria research.

Methods
Tis systematic review and meta-analysis were conducted based on the preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) [9], and Te Cochrane Handbook for Systematic Reviews of Interventions [10]. Tis study has been registered on PROSPERO with registration number CRD42021285722.

Patient and Public Involvement.
Since the article is a systematic evaluation based on the published original research, it does not involve patients and the public.

Inclusion/Exclusion Criteria
Te studies included in our systematic evaluation were clinical randomized controlled trials of tongue acupuncture in the treatment of poststroke dysarthria. Nonrandomized controlled trials, semirandomized controlled trials, animal experiments, medical record reports, systematic evaluation or review, qualitative studies, conference reports, and graduation theses were excluded.

Participants.
Te subjects were patients with dysarthria after stroke, including patients with intracerebral hemorrhage and cerebral infarction. Te criteria for exclusion included the following: (1) abnormal function caused by abnormal morphology of articulation organs; (2) complete aphasia; and (3) dysarthria not caused by cerebral apoplexy.

Interventions and Controls.
Te intervention group selected tongue acupuncture. Te intervention groups had more acupoints on the tongue and more complex operation methods than the control group.
Te control group selected traditional acupuncture. It means that the acupoints selected for treatment come from the mainstream treatment methods for poststroke dysarthria in textbooks or guidelines. Moreover, due to the particularity of stroke patients, patients need basic treatment during the clinical trial. To avoid bias, we included the clinical trial of unifed basic therapy in both the treatment and control groups.

Outcomes.
Te curative efect was our primary outcome measure. Te secondary outcome measure was the modifed Frenchay dysarthria assessment scale score (FDA) and the NIHSS score.

Data Extraction.
We made a detailed information extraction table using Microsoft Word, including the study's basic information, research object information, diagnostic criteria, the number of intervention groups and control groups, intervention methods, outcome indicators, followup time and measurement methods, analysis and statistics of results, and adverse events. Two researchers carried out the entire information extraction process back-to-back and the disputed items were discussed to determine the outcome after discussion. Finally, the main information of the study was summarized in a short table for display.

Risk of Bias Assessment.
Te Cochrane bias risk assessment tool [11] was used to conduct the quality evaluation, which covers selection bias, performance bias, attrition bias, reporting bias, and other biases. Te tool categorizes bias into three categories: "low risk," "high risk," and "unclear." Risk assessment was conducted by two researchers and any disputes were resolved through discussion.

Data Analysis.
Stata15.1 software was used for data synthesis analysis. We choose the odds ratio (OR) with a 95% confdence interval (CI) as the scale index for dichotomous outcomes (Clinical efcacy). Standardized mean diference (SMD) with 95% CI was selected as the index for the modifed Frenchay dysarthria assessment scale score. Mean diference (MD) with 95% CI was selected as the index for the NIHSS score. And a heterogeneity test was conducted among the studies, with the I 2 statistics [12]. Te fxed efect model was utilized if the heterogeneity result was P ≥ 0.1 and I2 ≤ 50%; otherwise, the random efect model was used. We also examined the impact of a single study on the overall meta-analysis through sensitivity analysis. Te detection of publication bias was not performed since the number of included studies was fewer [10].

Results
A total of 708 articles were included in the preliminary screening stage after searching 8 databases. We eliminated 338 duplicate articles and 231 irrelevant articles by reading titles and abstracts. 139 articles entered the fne screening stage of full-text reading. Finally, according to the inclusion and exclusion criteria of this study, 9 clinical studies were included for qualitative analysis. Te whole screening process is shown in Figure 1  acupuncture. All nine studies were conducted in China. Te age of onset was mainly about 60 years old, and the incidence rate of males was higher than that of females.

Interventions and Controls.
All participants of experimental groups selected tongue acupuncture. Te acupoints were mostly located under the tongue or on the surface of the tongue in the selected 9 trials. Te majority of the acupuncture methods involved oblique stabbing of the root of the tongue and then twisting the needle body, or pricking and bleeding on the selected acupoints. All the participants of the control group selected traditional body acupoints. Te average needle retention time was 30 minutes and the treatment course ranged from a month to two months.

Outcome Measures.
Clinical efcacy was reported in all nine studies, with six using the Frenchay dysarthria rating scale and two using the NIHSS score.

Risk of Bias in Individual
Trials. Two of the nine included studies' randomization was unclear. Tree trials were classifed as 'high risk' because participants were not blinded. Only one research explicitly described the use of the blind in data assessment, which was not mentioned in other studies. Tere was no attrition bias and reporting bias in all studies ( Figure 2).

Clinical Efcacy.
Clinical efcacy was reported in all 9 studies. Meta-analysis showed that tongue acupuncture was superior to traditional acupuncture in the treatment of poststroke dysarthria [OR � 3.62, 95%Cl (2.24, 5.85), P < 0.0001, I2 � 0.0%] (Figure 3(a)). Te homogeneity of the included studies was high and the fxed efect model was used. Te sensitivity analysis shows that the analysis model is relatively reliable (Figure 3(b)).

Te Modifed Frenchay Dysarthria Assessment Scale
Score (FDA). Only 3 studies provided FDA score data. Because of the diferences in the FDA scores of the three

4.3.3.
Te NIHSS Score. WMD was chosen as the evaluation index after combining the data from only two studies that reported NIHSS scores. In addition, since the heterogeneity evaluation was less than 50%, the fxed efect model was selected. Te result showed that the tongue acupuncture group was better than traditional acupuncture group in improving NIHSS score [WMD � 0.86, 95% Cl (0.15, 1.57), P � 0.017, I2 � 31.7%].

Classifcation Summary.
We classifed and summarized the included trials (Table 3). According to the diferent positions of acupoints, the included studies were divided into three categories: lingual surface, sublingual, and both lingual surface and sublingual. Additionally, according to the diferent operation methods of acupuncture, the research was divided into three categories: oblique stabbing into the tongue root, twisting the needle body after stabbing, and acupoints pricking. Among them, four studies used only one operation method, three studies used two, and two studies used three at the same time. Te count statistics of the studies are shown in Figure 5.

Subgroup Analysis.
Subgroup analysis was performed based on the classifcation of 9 studies to determine if tongue acupuncture with varied acupoint locations and diferent number of operation methods was superior to the traditional acupuncture group. And we also compared the diferences among the diferent subgroups. Te results are shown in Table 4.
In the subtypes of diferent positions of acupoints, the curative efects of the lingual surface group, the sublingual group, and the lingual surface combined with the sublingual group were better than those of the traditional acupoint selection group. Among the subgroups with diferent number of operation methods, the three subgroups were statistically signifcant, and the curative efect of the experimental group was better than that of the control group. By comparing the P values of the three groups, the subgroups using two operation methods [OR � 3.87, 95% Cl (1.67, 8.95), P � 0.002, I2 � 0.0%] or three operation methods [OR � 4.71, 95% Cl (1.75, 12.66), P � 0.002, I2 � 0.0%] were better than the subgroups using only one operation method [OR � 2.97, 95% Cl (1.43, 6.15), P � 0.003, I2 � 0.0%].

Adverse Event.
Acupuncture caused no serious adverse events in any of the nine studies included.

Acupuncture for the Poststroke Dysarthria.
Te mechanism of acupuncture for poststroke dysarthria may be considered from the recovery of central and peripheral nerve functions. According to the current research, it involved the bidirectional regulation of acupuncture on infammatory cells after stroke, regeneration, and promotion of nerve and blood vessels at the injured site, blood fow regulation at the ischemic site, and cerebral edema improvement. [22,23] A study has shown that acupuncture can reduce poststroke brain edema and promote the proliferation, migration, and diferentiation of neural stem cells [24], and can promote the generation of neurotrophic factors, so as to protect nerves [25]. Furthermore, it can regulate cerebral blood fow and activate cerebral angiogenesis after ischemic cerebral infarction [26]. For the peripheral nerve, it has been proved that acupuncture can promote the functional recovery of nerves and muscles for   [27,28]. Furthermore, acupuncture may promote facial nerve regeneration by upregulating the expression of GDNF and N-cadherin mRNA in facial neurons, which demonstrates acupuncture's nerve regeneration-promoting function [29].
In the treatment of dysarthria, many sound therapies, including yawning sighs, resonance sound therapy, visual and EMG biofeedback, progressive relaxation, and perilaryngeal massage, can relieve or rebalance laryngeal muscle hyperfunction and alleviate symptoms [30][31][32]

Location of acupoints
Study Acupoints treatment can improve dysphonia caused by increased muscle tone [33]. Acupuncture at relevant acupoints can shorten the distance between the hyoid bone and thyroid cartilage [34], which can alleviate the tension and spasm of neck muscles.
Tis also provides evidence of curative efects for the treatment of dysarthria with tongue acupuncture. Most of the acupoints in tongue acupuncture therapy involve the spasm muscles of the neck area but traditional acupuncture did not realize this. Tis may be the reason why tongue acupuncture is superior to traditional acupuncture.

Interpretation of Results.
Based on the results of this meta-analysis, tongue acupuncture was shown to be more efective than traditional acupuncture in the treatment of poststroke dysarthria. Tongue acupuncture is superior to traditional acupuncture in efcacy index, FDA score, and NIHSS score. It indicates that tongue acupuncture is more efective than traditional acupuncture at restoring language and nerve function in patients with poststroke dysarthria. Trough the analysis of the subgroups of the tongue acupuncture group in the acupoint position selection, we conclude that the curative efect of sublingual acupoint selection or the lingual surface combined with the sublingual acupoint selection group is better than that of the traditional point selection group. It is suggested that sublingual acupoint selection has a better efect than lingual surface acupoint selection and that lingual surface and sublingual combined acupoint selection has an efect similar to simple sublingual acupoint selection. Te results imply that sublingual acupoint selection has the advantage of a curative efect in clinics.
Te curative efects of the three groups are better than the control group in the subgroup analysis of the number of acupuncture operation methods but the analysis results suggest that using more than two methods is better than using only one method. Te efect of using two method groups is similar to using three method groups. It can be considered that an appropriate number of acupuncture manipulations can improve the curative efect, and the manipulation has a cumulative efect.

Te Control of Study Homogeneity and Evaluation Basis of Efcacy Index.
To ensure the consistency and analyzability of the included studies, we strictly selected the control group and the experimental group of the included studies. All included studies were the comparison between tongue acupuncture and traditional acupuncture. In the tongue acupuncture group, the acupoints on the surface of the tongue or under the tongue were selected. Te acupoints in the traditional acupuncture group were chosen from those recommended in textbooks or guidelines, such as body acupuncture, scalp acupuncture, and neck acupuncture. To ensure that the diference in curative efect only comes from  tongue acupuncture, the studies we included ensure the consistency of basic treatment. Moreover, the diference in treatment between the experimental group and the control group is only in the acupoint selection and acupuncture manipulation. Te Frenchay dysarthria rating scale assigned a total score of 28 points based on refex, respiration, lip, jaw, soft palate, throat, tongue, and speech. Recovery: the speech function reached grade 5, with a score of 28∼27. Remarkable efect: the speech function evaluation was improved by 2∼4 grades, with a score of 26∼18. Improvement: the evaluation of speech function was improved by 1 grade, with a score of 17∼14; Invalid: there was no change in speech function evaluation, and the score was 6∼0.

Research Evaluation and Prospects.
Te limitation of this study is that only 9 studies were included, and all of them had the limitations of small sample size and lack of rigorous research methods. Te observation index was single, only curative efect Frenchay score, and NIHSS score. Te safety issues of the included studies were not reported in detail and the safety assessment was not considered. Te advantage of this study is that it will further classify and evaluate the tongue acupuncture group's acupoint selection and operation methods, as well as strictly control the intervention methods included in the study.
To improve the clinical evidence of tongue acupuncture in the treatment of poststroke dysarthria and to perfect the parameters of acupuncture, researchers can focus on the superior efcacy of tongue acupuncture, expand the sample size, improve the research methods, and explore the superior acupoint selection and acupuncture manipulation in future clinical research. Moreover, the research on the mechanism of acupuncture in the treatment of poststroke dysarthria is still in the research blind area. More focus should be given to fundamental research in this area.

Conclusion
Tis meta-analysis shows that tongue acupuncture is superior to traditional acupuncture in terms of clinical efcacy, FDA score, and NIHSS score in the treatment of poststroke dysarthria. Te efect of acupoints selection of sublingual is better than that on the lingual surface. Also, the results suggested that the more acupuncture manipulation were used, the better were the results. In clinical practice, tongue acupuncture (especially sublingual acupoint selection) can be added to treat poststroke dysarthria, and the use of acupuncture manipulation can be increased. Te actual efcacy and better parameters of tongue acupuncture need to be confrmed by large samples and more rigorous clinical trials, and the clinical safety also needs more experiments to evaluate.

Data Availability
Te research results will be published in public journals and the data can be shared by colleagues. No data were used to support this study.

Ethical Approval
Tis study is a literature study, and the experimental design does not involve patients. Ethical review is considered unnecessary. Te results will be published in a peer-reviewed journal for public dissemination.