I. INTRODUCTION
Headache is a common complaint with prevalence in the general population such as children and adults of about 16%. It is divided into primary headache and secondary headache by factors1-2).
According to the International Headache Society classification (ICHD-3), the secondary headaches are classified as Headache attributed to trauma or injury to the head and/or neck, Headache attributed to cra-nial or cervical vascular disorder, Headache attributed to non-vascular intracranial disorder, Headache attrib-uted to infection, Headache attributed to disorder of homeostasis, Headache or facial pain attributed to dis-order of the cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cervical structure, and Headache attributed to psychiatric disorder. Especially Cervicogenic headache (CeH) is including headache attributed to trauma or injury to the head and/or neck, headache pain attributed to disorder of the cranium, neck or cervical structure3).
Cervicogenic headache defined as headaches origi-nating from cervical spine structures including cervical facet joints, cervical intervertebral discs, skeletal mus-cles, connective tissues, and neurovascular structures is a secondary headache characterized by unilateral headache, and symptoms and signs of neck involve-ment. It is heavily influenced by neck movement, head position or external pressure of the upper cervical or occipital region on the inconvenient region4,5).
The prevalence of CeH varies in the general pop-ulation depending on the diagnostic criteria, i.e. 1.0% to 4.6% applying according to criteria in the Cervico-genic Headache International Study Group (CHISG) while it was 2.5 % applying the International Headache Society (IHS) criteria6).
On the pathological point of view, CeH may origi-nate from dysfunction of various anatomic structures in the cervical region. In particular, the dysfunction of the trigerminal and upper three cervical spinal nerves is likely to lead to the headache. That is, improvement of cervical dysfunction significantly alleviates symp-toms3,7).
CeH is usually caused by trauma of the neck, and is often caused by dystonia due to poor posture, spinal stenosis, and herniation of cervical intervertebral disc8).
Generally, Treatment of CeH is to using the pharma-cological intervention such as a painkiller, or non- pharmacological intervention such as the ganglionic blockade using local anesthetic, occipital nerve block-ade and rami medialis blockade of intervertebral joint in western medicine9,10).
In Korean medicine, Acupuncture, Pharmacoacu-puncture, Mini/scalpel Acupuncture (MA), Chuna Manual Therapy (CMT) are using for intervention of CeH and multiple studies on CeH are actively proceeding11-14).
Especially, CMT is a specialized type of manual ther-apy where the practitioner uses manual and/or phys-ical force with optional devices to apply appropriate correcting force to specific body areas to treat various dysfunctions and pathophysiologic conditions15).
CMT has a good effect to improve the structural problems of the human body, and it is estimated to be very effective in treating CeH, but there are barely a few domestic studies14,16,17).
Thus, This study is conducted to evaluate the effi-cacy of CMT for treatment of CeH through systematic review and Meta-analysis of randomized controlled tri-als (RCTs) as a preceding research in order to further research the effective of CMT for patients suffered from CeH.
II. METHODS
1. Data sources and searches
We conducted a systematic review and meta-analy-sis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines18).
The databases were searched from their inception through August 31, 2018. The literature search was performed on August 1, 2018 by two investigators, who are Korean medical doctors. Results published in English, Chinese, Korean were considered. Data were recorded and assessed using Microsoft Excel 2010.
The gray literature was excluded. We also per-formed a manual search to find the ongoing clinical studies. The reference lists of included studies were screened to confirm that there are missing studies.
1) Identifying studies
International Electrical database (English)
・ MEDLINE
・ Elsevier-EMBASE
・ Cochrane Library Database
Chinese database (Chinese)
・ CAJD (China Academic Journal network publishing Database)
Domestic databases (Korean)
・ KISS (Korean-studies Information Service System)
・ KMBase (Korean Medical database)
・ Korean Traditional Knowledge Portal
・ NDSL (national discovery for science leaders)
・ OASIS (Oriental Medicine Advanced Searching In-tegrated System)
2) Key words
The search terms:
・ In English, Chinese, and Korean: ‘Post-traumatic headache*[MeSH term]’, ‘Cervicogenic headache’, ‘Cervical headache’, ‘Headache of cervical origin’, ‘Craniocervical region in headache’, ‘颈源性头痛’, ‘颈枢部性头痛’, ‘颈枢因性头痛’, ‘颈枢性头痛’, ‘颈部性头痛’, ‘Chuna’, ‘Tuina’, ‘Spinal manipulation’, ‘Manipulative therapy’, ‘Chiropractic’, ‘Massage therapy’, ‘Osteopathic treatment’, ‘Spinal mobi-lization’, ‘Manual therapy’, ‘推拿’ , ‘手法’, ‘경추인성 두통’, ‘경추성 두통’, ‘경부성 두통’, ‘추나’, ‘수기 치료’, ‘카이로프랙틱’, ‘척추교정’, ‘도수치료’, ‘도수치료’ and ‘정골요법’
・ Through consultation with CMT specialist, ‘Spinal manipulation’, ‘Manipulative therapy’, ‘Chiropractic’, ‘Massage therapy’, ‘Osteopathic treatment’, ‘Spinal mobilization’, ‘Manual therapy’ were judged as CMT.
2. Study selection
The study selection was performed independently by two reviewers with disagreement resolved by dis-cussion and adjudication. Duplication of studies was excluded using EXCEL database by comparing the title, the abstract, and author key words published. The CAJ Databases did not allow logical searches with AND, so we used simple combinations of the search words. We selected in the studies of CMT used as an intervention, but the CMT methods were not limited. Only CMT in-terventioned studies were selected and CMT combined another treatment were excluded. Inappropriate stud-ies were excluded by examining the title and the abstract. All papers with at least an abstract in English were included.
1) Types of studies
Studies mentioning randomized controlled trials (RCTs) of CMT for CeH were considered. And a qua-si-random method was allowed. Studies that did not mention RCTs, studies of not using a quasi-random method at least, case series, observational, cohort, case control, qualitative studies, Uncontrolled trials and lab-oratory studies were excluded.
2) Types of participants
The patients selected were diagnosed with CeH clinically. Studies involving pediatric participants (<19 year) or participants unrelated with headache of cer-vical origin are excluded. No restrictions to gender and race were imposed.
3) Types of intervention
The intervention should be CMT only. In this study, the intervention was included such as Spinal manipu-lation, Manipulative therapy, Chiropractic, Massage therapy, Osteopathic treatment, Spinal mobilization, Manual therapy through experts advice whether it is applicable to the act of CMT. Other forms of treat-ments (unrelated CMT such as Qi gong etc.) were excluded. Studies that assessed the combined treat-ment effect of CMT with Electroacupuncture, Laser therapy, Pharmacoacupuncture, Mini scalpel acupunc-ture, Auricular acupuncture, Pharmacotherapy, Physio-therapy were excluded.
4) Types of control
We excluded studies that included controls that cor-responded to CMT behavior such as Massage therapy (control), CMT (control) itself, Complex therapy (con-trol) including CMT. Usual care or Sharm CMT were included allowedly.
5) Types of outcome measures
The outcome measure was set to Severity of CeH pain and Clinical total Effective Rate (CER) at the End of treatment (EOT) as the primary outcome. CeH Pain severity was measured by Visual Analogue Scale score (VAS) and the CER calculated by the change in CeH symptom. The CER was calculated using the following formula: CER=N1+N2/N, where N1, N2, and N are the number of patients who are markedly improved, im-proved, and who comprise the sample size, respec-tively. Headache numerical rating scale (NRS), Head-ache Frequency, Headache Duration, Headache Inten-sity, Transcranial Doppler (TCD), Range of Motion (ROM), Mcgill Pain Index, Cervical vertebra activity score were the secondary outcome.
3. Data extraction
Data extraction was performed independently by two unblinded investigators and discrepancies were resolved through discussion. Data from the articles were validated and extracted using a predefined data extraction form. Study characteristics were study de-sign, sample size, age range, treatment duration, inter-vention, control, adverse events and outcome.
4. Risk of bias assessment
To assess the methodological quality of RCTs in-cluded, the Risk of Bias tool provided by the Cochrane Collaboration was used, and we obeyed the principles for assessing risk of bias19). Because baseline imbalance in factors that are strongly related to outcome meas-ures can cause other potential biases in the estimation of an intervention effect in RCTs.
5. Data synthesis
The quantitative data of primary and secondary out-comes were combined and meta-analysis was per-formed according to effects of CMT, using RevMan software version 5.3 (Cochrane, London, UK).
6. Identifying heterogeneity
A random-effect model was considered possible clinical heterogeneity among the included studies us-ing the chi-square test, the tau2 test, and Higgins I2statistics18).
III. RESULTS
1. Study selection
The titles and/or abstracts of 509 studies were screened, and the full texts of 202 articles were re-viewed (Fig. 1). Ineligible studies reviewed in titles and/or abstracts were excluded (n=188). Of the 202 articles reviewed in full text, 20 studies were identified for inclusion in systematic review (Luan et al. 2002), (Sun 2005), (Jiang 2005), (Chen et al. 2007), (Wang et al. 2007), (Yan 2007), (Tang et al. 2008), (Huang 2008), (Wang et al. 2008), (Wei et al. 2008), (Wei 2009), (Wang et al. 2009), (Lee et al. 2011), (Yu 2011), (Quan et al. 2011), (Liu et al. 2014), (Xu et al. 2016), (Ding 2017), (Aleksander et al. 2017), (Wang et al. 2018)20-39). Ineligible studies reviewed in full text were excluded (n=121), reason that they were RCTs but not of CeH (n=2), not RCTs (n=22), combined other treatment (n=129), case study or series (n=16), duplication studies (n=4), inappropriate measurement targets (n=9).
Fig. 1. PRISMA flowchart of study selection.
20 studies were identified for inclusion in meta- analysis (Luan et al. 2002), (Sun 20(Jiang 2005), (Wang et al. 2007), (Yan 2007), (Chen et al. 2007), (Huang 2008), (Wei et al. 2008), (Wei 2009), (Wang et al. 2009), (Lee et al. 2011), (Quan et al. 2011), (Yu 2011), (Liu et al. 2014), (Xu et al. 2016), (Ding 2017), (Tang et al. 2008), (Aleksander et al. 2017), (Wang et al. 2018).
2. Study description
1) Characteristics of included studies
In all, 20 studies were included for systematic re-view and all studies for meta-analysis. The summary of the included RCTs are presented in Table 1 and 2.
Table 1. General Characteristics of Included RCTs of CMT for CeH
RCT: Randomized Clinical Trial, CMT: Chuna Manual Therapy, CeH: Cervicogenic headache, n.r: not reported, yr: year, M: month.
19 trials originated from the China ((Luan et al. 2002), (Sun 2005), (Jiang 2005), (Chen et al. 2007), (Wang et al. 2007), (Yan 2007), (Tang et al. 2008), (Huang 2008), (Wang et al. 2008), (Wei et al. 2008), (Wei 2009), (Wang et al. 2009), (Lee et al. 2011), (Yu 2011), (Quan et al. 2011), (Liu et al. 2014), (Xu et al. 2016), (Ding 2017), (Wang et al. 2018)), one trials from Norway (Aleksander et al. 2017).
In 20 RCTs comparisoning 1,673 participants were included for the systematic review. They were all diag-nosed CeH and participated in studies. Mean ages of 16 trials were from 32.10 to 52.17 years. 4 trials were uncertain. Mean duration was 1 day to 16 years in range or 69.45 days to 13.8±10.5 years in mean but it is difficult to define the characteristics of partic-ipants because many studies had not been described accurately.
All the trials used CMT. In all RCTs, 18 trials were two-armed parallel group design, and two trials were three-armed group design. 6 trials were designed study as CMT versus Physiotherapy (PT) ((Jiang 2005), (Chen et al. 2007), (Wei 2009), (Wang et al. 2009), (Lee et al. 2011), (Ding 2017)). 10 trials were designed as CMT versus Pharmacotherapy ((Luan et al. 2002), (Sun 2005), (Yan 2007), (Wang et al. 2007), (Wei et al. 2008), (Huang 2008), (Yu 2011), (Quan et al. 2011), (Liu et al. 2014), (Xu et al. 2016)). 1 trials were designed as CMT versus Injection therapy (Wang et al. 2008), 1 trials were designed as CMT versus PT and Pharmacother-apy (Tang et al. 2008), 1 trials were designed as CMT versus sharm CMT or usual management (pharmaco-therapy) (Aleksander et al. 2017), and 1 trials were de-signed as CMT versus acupuncture treatment (Wang et al. 2018).
CMT treatment time of 13 trials was from 3 to 30 minutes but 7 trials were not mentioned. In treatment duration, the range of consecutive treatment days was 10 to 21 in 11 trials. 9 trials were not mentioned. And total number of treatment frequency was from 2 to 15 times, most of trials were treated about 10 times.
In designed studies as CMT versus Physiotherapy, hey used traction therapies, laser irradiation therapies, Computerized Intermediate frequency therapy, Trans- cutaneous electrical Nerve Stimulation (TENS) and in designed as CMT versus Pharmacotherapy, they used various kinds of medications such as Difenidol, Oryzanol, Vitamin B1, Meloxicam, Flunarizine Hydro-chloride, Indomethacin, Vitamin B6, Sibelium, Yangxue Qingnao Granules, Ibuprofen.
2) Outcome measures
16 trials examined in this study used VAS or CER as a main outcome measurement (Table 2).
Table 2. Intervention Characteristics and Main Outcomes of Included RCTs of CMT for CeH
Table 2. Continued
AE: Adverse event, CMT: Chuna Manual Therapy, CeH: Cervicogenic headache, n.r: no reported, VAS: Visual Anlog Scale, CER: Clinical total Effective Rate, IV: intravenous, IM: Intra-Muscular, TCD: Trans-cranial Doppler, ROM: Range of motion, NSD: Not significantly difference, NRS: Numeric Rating Scal, M: month, min: minute, TENS: Trans-cutaneuous electrical stimulation.
4 trials compared groups between CMT versus PT (Conventional physical therapy such as traction thera-pies, laser irradiation therapies, Computerized Inter-mediate frequency therapy and TENS) in VAS ((Jiang 2005), (Wang et al. 2009), (Lee et al. 2011), (Ding 2017)), and there was no significant difference in re-ducing pain of CEH between CMT and PT in Lee (2011). However in Jiang (2005), Wang et al (2009), Ding (2017) CMT groups were improved significantly compared to PT groups (p<0.01 or p<0.05). In Jiang (2005), VAS had a significantly change compared to Laser therapy groups (p<0.05). In Wang et al (2009) and Ding (2017), there were significantly change in VAS compared to Traction groups (p<0.01 and p< 0.05).
4 trials compared groups between CMT versus PT in CER ((Chen et al. 2007), (Wei 2009), (Wang et al. 2009), (Ding 2017)). In Chen et al. (2007), CER im-proved significantly compared to TENS groups (p< 0.05). In Wei (2009), CER improved significantly com-pared to Intermediate frequency therapy apparatus groups (p<0.05). In Wang et al. (2009) and Ding (2017), Both of their CER improved significantly com-pared to Traction therapy groups (p<0.05).
3 trials compared groups between CMT versus Pharmacotherapy in VAS ((Wang et al. 2007), (Quan et al. 2011), (Liu et al. 2014)). They all were significantly reduced VAS compared to Pharmacotherapy groups in-cluding herbal medicine and Western medications. In Wang et al. (2007), VAS reduced significantly compared to control group using Yangxue Qingnao Granules (herbal medicine) (p<0.05). and in Quan et al. (2011) and Liu et al. (2014), reduced significantly compared to Pharmacotherapy group, too (p<0.01 and p<0.05).
10 trials compared groups between CMT versus Pharmacotherapy in CER ((Luan et al. 2002), (Sun 2005), (Yan 2007), (Wang et al. 2007), (Wei et al. 2008), (Huang 2008), (Yu 2011), (Quan et al. 2011), (Liu et al. 2014), (Xu et al. 2016)). They all improved CER sig-nificantly compared to Pharmacotherapy group (p< 0.01 and p<0.05).
However in some studies, there were no significant result. In Lee (2011), CMT group was compared to Ultra laser therapy group, but there were no significant difference in VAS and Mcgill Pain Index (NSD). In Aleksander et al. (2017), they compared groups among CMT versus sharm CMT or Usual treatment such as Pharmacotherapy (3-arm study). But they did not men-tioned results. In Chen et al. (2007), CMT improved in CER (p<0.05), Headache NRS (p<0.01), Headache frequency (p<0.01) and Headache duration (p<0.01) but ROM did not significantly (NSD).
3. Risk of bias assessment
For the methodological quality, risk of bias (ROB) using modified Jadad score and the Cochrane Collabo-ration’s tool for assessing ROB were used18,19). l8 stud-ies of 20 trials did not mentioned Random sequence generation and all 20 trials did not randomly allocated participants. Furthermore 19 studies excluding one study had high risks of participants and personnel on Reflecting the characteristics of the intervention (CMT). And all trials did not mentioned concerning the blinding of the outcome assessment. Wei et al. (2008), Liu et al. (2014) and Aleksander et al. (2017) showed attrition bias because of drop-outs due to dissatisfaction with treatment. Except for only one study, 19 studies showed reporting bias. Especially Wei (2008) was reported differently analyzed number in contents. In other bias, Liu et al. (2014) and Jiang (2005) had a significant difference in duration between the two groups at baseline (Fig. 2).
Fig. 2. Risk of bias summary.
According to the Jadad scoring system, all 20 trials were randomized in various ways including a qua-si-random method. 2 trials used a random number Table of blocked randomization. So 2 trials randomized as appropriate methods ((Wang 2007), (Wei 2009)), No one randomized as inappropriate method and 18 trials did not reported randomization method ((Luan et al. 2002), (Sun 2005), (Jiang 2005), (Yan 2007), (Chen et al. 2007), (Huang 2008), (Wang et al. 2008), (Tang et al. 2008), (Wei et al. 2008), (Wang et al. 2009), (Lee et al. 2011), (Quan et al. 2011), (Yu 2011), (Liu et al. 2014), (Xu et al. 2016), (Ding 2017), (Aleksander et al. 2017), (Wang et al.2018)).
Only one trials were double-blinded (Aleksander et al. 2017), and other 19 trials did not mentioned. Thus, one trials obtained a score of 3 (Aleksander et al. 2017), 3 trials received a score of 2 ((Jiang 2005), (Wang 2007), (Wei 2009)), 16 trials received a total score of 1 ((Luan et al. 2002), (Sun 2005), (Yan 2007), (Chen et al. 2007), (Huang 2008), (Wang et al. 2008), (Tang et al. 2008), (Wei et al. 2008), (Wang et al. 2009), (Lee et al. 2011), (Quan et al. 2011), (Yu 2011), (Liu et al. 2014), (Xu et al. 2016), (Ding 2017), (Wang et al. 2018)). Therefore, 19 studies except Aleksander et al. (2017) received scores of negative 1 or 2.
4. Outcome Results
1) VAS change of CMT versus Pharmacotherapy
The data of 3 studies compared Chuna Manual Therapy (CMT) and Pharmacotherapy were synthesis in VAS change (Fig. 3). VAS is a measurement instru-ment for subjective characteristics or attitudes that cannot be directly measured. In this study, VAS was calculated based on feeling of patient as the CeH symptom change after receiving CMT for 4 to 10 times or pharmacotherapies.
Fig. 3. The forest plot of VAS: Chuna Manual Therapy versus Pharmacotherapy.
2) CER change of CMT versus Pharmacotherapy
The data of 10 studies compared Chuna Manual Therapy (CMT) and Pharmacotherapy were synthesis in CER change (Fig. 4). CER was calculated based on changes in improvement CeH symptom after receiving CMT for 4 to 15 times or pharmacotherapies.
Fig. 4. The forest plot of CER: Chuna Manual Therapy versus Pharmacotherapy.
3) VAS change of CMT versus Physiotherapy
The data of 4 studies compared Chuna Manual Therapy (CMT) and Physiotherapy were synthesis in VAS change (Fig. 5). VAS was calculated based on feel-ing of patient as the CeH symptom change after re-ceiving CMT for 2,3 to 10 times or Physiotherapies.
Fig. 5. The forest plot of VAS: Chuna Manual Therapy versus Physiotherapy.
4) CER change of CMT versus Physiotherapy
The data of 4 studies compared Chuna Manual Therapy (CMT) and Physiotherapy were synthesis in CER change (Fig. 6). CER was calculated based changes in improvement CeH symptom change after receiving CMT for 2,3 to 10 times or Physiotherapies.
Fig. 6. The forest plot of CER: Chuna Manual Therapy versus Physiotherapy.
5) VAS change of CMT versus Combined therapy
2 studies compared Chuna Manual Therapy (CMT) and Combined therapy group corresponds to usual care. They were synthesis in VAS change (Fig. 7). This VAS was calculated based on feeling of patient as the CeH symptom change after receiving CMT for 7 to 12 times or combined therapies such as Pharmacother-apies, Physiotherapies or both.
Fig. 7. The forest plot of VAS: Chuna Manual Therapy versus Combined therapies
6) Safety
In 20 studies analyzed, Jiang (2005), Wang et al. (2009), Aleksander et al. (2017) reported no adverse events. The others did not mentioned. It is unlikely to conclude about the Adverse events of only three of the 20 studies.
IV. DISCUSSION
Chuna Manual Therapy (CMT) is a non-surgical treatment modality that includes the use of skilled hands directed to the patient’s spine and extremities for the purpose of treating and restoring a variety of symptoms and conditions. CMT has long been used to treat various diseases, the pain control mechanism un-derlying the effect of CMT is various. So CMT con-stitutes a wide variety of different techniques which may be categorized as follows: thrust manipulation, mobilization, static stretching, and muscle energy techniques40).
Cervicogenic headache (CeH) is a syndrome charac-terized by chronic hemicranial pain that is referred to the head from either bony structures or soft tissues of the neck. CeH is known to be a problem of the upper cervical vertebrae that the trigeminocervical nucleus is a region of the upper cervical spinal cord where sen-sory nerve fibers in the descending tract of the trige-minal nerve (trigeminal nucleus caudalis) are believed to interact with sensory fibers from the upper cervical roots41). CeH is a typical treatment target of CMT, and it is also a disease that can be encountered frequently in the clinical field
CMT has been reported to be effective for muscu-loskeletal disorder including CeH17,42,43). CeH occurs from the problem of the cervical region, CMT, a useful tool for spinal therapy, is also a therapeutic tool for CeH. So 3 reviews concluded that there was a effec-tiveness from previous RCTs of CMT compared to oth-er intervention for improving CeH. but there were no sufficient conclusive evidence of its efficacy17,42,43). But, previous studies have shown that heterogeneity is val-id, control group of the study was not clear. Presenting reviews of synthesis has some error in application to clinical treatment, as some reviews included trials with tension type headache, migrane, or synthesized several mixed types of treatments with CMT, so these might be not appropriate in assessment of effect of CMT to CeH in general. Thus, in this study, selective inter-vention was determined as CMT as monotherapy for CeH patients. CMT was the selective intervention, and other treatment modalities such as herb remedies and other types of intervention were all excluded.
All trials described the trials as randomized con-trolled trials (RCTs) in various ways, the study, which was not clearly described, was not given a score. All studies had not mentioned concerned with allocation concealment, so they were suspicious of the quality of the study. In blinding of participants and personnel, only one trial mentioned. 19 trials had high risk of blinding of participants and personnel. Also all studies mentioned nothing of blinding of the outcome as-sessors. 17 studies included no-dropouts but 3 studies had a high risk of incomplete outcome because ana-lyzed number was not same at the beginning of the report and result or the measurement value of report-ing is unclear. In other bias, Jiang (2005) and Liu (2014) had a significant difference in duration between the two groups at baseline.
This review aimed to evaluate the clinical effect of Chuna Manual Therapy (CMT) for Cervicogenic Head-ache (CeH) as monotherapy compared to other inter-vention. The comprehensive search in this study in-volved 20 RCTs of CMT for CeH. Based on the results of our study, CMT as a monotherapy significantly re-duced Pain or discomfortance of CeH by measured by Clinical total Effective Rate (CER) and Visual Analogue Scale (VAS) after the intervention, with no consistent results regarding CeH totally.
However, there were favorable results for CMT group compared with pharmacotherapy group, physi-otherapy group and combined treatment group after the intervention.
CMT group showed improvement effect using CER and VAS compared with pharmacotherapy, but their heterogeneity were significant. Each of the 20 selected studies showed that CMT was effective. Despite the positive results of each study, the heterogeneity of the study group was significant. To further evaluate, sub-group analysis was conducted. Considering the differ-ent frequency of treatments between CMT group in VAS, We divided CMT group into subgroup (Treated 10 times and more) and subgroup (Treated less than 10 times). CMT that performed less than 10as monotherapy showed significantly difference in VAS com-pared with pharmacotherapy and showed no hetero-geneity. Also CMT that performed more than 10 times as monotherapy was very effective in CER compared with pharmacotherapy. Also CMT group in CER con-ducted subgroup analysis. In the same way, We divided into two subgroups (Treated 10 times and more) and subgroup (Treated less than 10 times). CMT group that performed 10 times and more showed significantly dif-ference in CER compared with pharmacotherapy and showed no heterogeneity.
Comparing with physiotherapy, CMT group ob-tained poor result in VAS but in CER showed sig-nificant effectiveness. Especially CMT was effective in VAS and CER compared to Traction therapy, Electro-therapy such as TENS and Computerized intermediate frequency therapy, Laser therapy. And compared to combined therapy, CMT was very effective, too.
However, these seemingly positive results about ef-ficacy of CMT for CeH should be interpreted cautiously because of a limited number of studies included in this review, heterogeneities among them and low meth-odological quality of them42,44). NSAIDs are currently regarded as first-line treatment based on extensive evidence, and physiotherapy is also the most com-monly used pain treatment method in both East and West. This treatments not only easy but also simple treat to the positive results of economical outcomes, but CMT should not be regarded as a substitute for conventional pharmacotherapy in routine treatment course. However, it may be considered to utilize in the managements of patients having polypharmacy trouble or patients who current treatment is ineffective.
This review has some serious limitations and that should be taken seriously into account. First, the age range of the participants in the included studies varied from 17 to 69 years except unmentioned report, and the range of the disease period of CeH are vary from 1 day to 20 years. Due to these demographic limits, the analyzed data may not be generalized. Second, some synthesized outcomes of CMT have substantial statistical and clinical heterogeneities included in the quantitative analyses. It may be caused by difference in characteristics of participants. And it will be weaken the reliability of the data. Third, included studies of this paper were evaluated as Low methodological quality. The major responsibility of some studies was the lack of proper method of blinding. However, con-sidering the characteristics of CMT, it was hard to car-ry out blinding method such as sham CMT. Therefore, there is a need to minimize the elements that can cause other bias, such as blinding of outcome assessor. No trial reported a formal sample size calculation, and inadequate sample size can overestimate the efficacy of CMT. Fourth, 19 of 20 studies in analysis included are published in China, and this may limit the univer-sality of the results of this review. Fifth, since there have been no studies reporting IRB approval, there is a limit to the ethical aspects of the studies involved.
Further studies of higher quality, appropriate sample size via calculation, and long-term are needed to solid-ify the results of this review. Inclusion criteria about participant and intervention should be clearly speci-fied to determine who could benefit from CMT and which methods of CMT are most effective. The report-ing of RCTs should follow Consolidated Standards of Reporting Trials (CONSORT) statement44). Standardized monitoring of adverse events related to CMT is also needed. Studies comparing technique of CMT and standardized procedures for CeH are also needed. Finally, meta-analysis of added study may be con-ducted to examine the efficacy of various CMT modal-ities to help clinical decision making.
V. CONCLUSION
20 randomized clinical trials were included in quan-titative and qualitative study. The risk of bias as well as the effect size was vary in all the trials. Comparing to Physiotherapy and Pharmacotherapy Mainly, the ef-ficacy of CMT was proved. Although CMT was sig-nificant heterogeneous, it was generally more effective than physiotherapy, pharmacotherapy.
According to current evidence, CMT as monother-apy might have benefits on Cervicogenic Headache patient. Therefore, this treatment has the potential of non-pharmacological methods that can be used in pa-tients who are not responding to the conventional pharmacotherapy or physiotherapy.
However, since the number of studies included and the sample sizes were small, and the methodological quality was poor, these findings should be interpreted with great caution. Further well-designed studies need to be conducted to confirm these results.
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