Background: Acupuncture treatment for tinnitus has received attention owing to its potential as an alternative to conventional treatment modalities. We conducted a scoping review to identify detailed information on acupuncture treatment methods used in clinical studies and to provide useful information for practitioners, patients, and researchers. Methods: MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), Embase, Oriental Medicine Advanced Searching Integrated System (OASIS), Korean Research Information Sharing Service (RISS), DataBase Periodical Information Academic (DBPIA), and the China National Knowledge Infrastructure (CNKI) were searched from their inception to December 2023. This review included single-arm trials, open-label randomized controlled trials (RCTs), and double-blind RCTs using needle-type acupuncture to treat tinnitus in English, Chinese, and Korean. We investigated basic and detailed information on the acupuncture treatment methods, assessment methods, and study outcomes. Network analysis was also conducted to evaluate the centrality between acupoints in the double-blind RCTs. Results: We included 106 articles. There were 11 single-arm trials, 90 open-label RCTs, and 5 double-blind RCTs. Most (89.6%) of these studies were conducted in China. Manual acupuncture was the most common type of acupuncture in treatment group. A total of 119 acupuncture points were used 1,138 times. The most frequently used acupoints were local points around the ear (TE17, GB2, SI19, and TE21). Both local and distant acupoints were used simultaneously in these studies. The treatment duration of 20–39 days, 10 to 19 sessions of treatment, the mean acupuncture duration of 30 min, needle diameter of 0.30 mm × 40 mm, and needling depth over 30 mm and less than 50 mm were confirmed as the most common. Conclusion: These study outcomes will enable future acupuncture studies on tinnitus to perform more effective and standardized acupuncture treatments in selecting acupoints and procedures. Furthermore, the study has implications for informing clinicians and students about more impactful acupuncture strategies for addressing tinnitus.

Hintergrund: Die Anwendung von Akupunktur bei Tinnitus erhält seit einiger Zeit Aufmerksamkeit als potenzielle Alternative zu konventionellen Behandlungsmodalitäten. Wir führten einen Scoping-Review durch, um detaillierte Informationen zu den in klinischen Studien angewandten Akupunktur-Behandlungsmethoden zu sammeln und nützliche Informationen für Praktiker, Patienten und Forscher bereitzustellen.Methoden: MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), Embase, Oriental Medicine Advanced Searching Integrated System (OASIS), Korean Research Information Sharing Service (RISS), DataBase Periodical Information Academic (DBPIA) und die China National Knowledge Infrastructure (CNKI) wurden von ihrem jeweiligen Beginn bis Dezember 2023 durchsucht. In diese Übersichtsarbeit wurden einarmige Studien, offene, randomisierte, kontrollierte Studien (RCTs) sowie doppelt verblindete RCTs zu Nadel-Akupunktur zur Behandlung von Tinnitus in englischer, chinesischer und koreanischer Sprache einbezogen. Wir untersuchten grundlegende und detaillierte Informationen zu den Akupunktur-Behandlungsmethoden, Untersuchungsmethoden und Studienergebnissen. Außerdem wurden Netzwerkanalysen zur Beurteilung der Zentralität zwischen Akupunkten in den doppelt verblindeten RCTs durchgeführt.Ergebnisse: 106 Artikel wurden eingeschlossen. Sie behandelten 11 einarmige Studien, 90 offene RCTs und 5 doppelt verblindete RCTs. Die meisten (89,6%) dieser Studien waren in China durchgeführt worden. Manuelle Akupunktur war die häufigste Form der Akupunktur in den Behandlungsgruppen. 119 Akupunkturpunkte wurden insgesamt 1’138 Mal verwendet. Die am häufigsten verwendeten Akupunkte waren lokale Punkte im Bereich des Ohrs (TE17, GB2, SI19 und TE21). Jedoch wurden in den Studien lokale und entfernte Akupunkte gleichzeitig angewendet. Außerdem wurde festgestellt, dass die Behandlungsdauer am häufigsten 20 bis 39 Tage betrug, die Zahl der Sitzungen 10 bis 19, die mittlere Akupunkturdauer 30 Minuten, die Nadelgröße 0.30 mm × 40 mm und die Einstichtiefe zwischen 30 mm und weniger als 50 mm.Schlussfolgerung: Diese Studienergebnisse bieten eine Grundlage für künftige Studien zu Akupunktur bei Tinnitus, um durch die Auswahl der Akupunkte und Verfahren wirksamere und standardisierte Akupunkturbehandlungen durchzuführen. Darüber hinaus hat die Studie Implikationen für die Aufklärung von Praktikern und Schülern über wirkungsvollere Akupunkturstrategien zur Behandlung von Tinnitus.

KeywordsAkupunktur, Tinnitus, Traditionelle asiatische Medizin, Komplementärmedizin, Narrative Übersichtsarbeit

Tinnitus is a symptom of perceiving sound without external auditory stimulation [1] that affects 4.6–30% of the global population [2]. In Korea, the prevalence of tinnitus is 19.7% among the population aged >12 years [3]. Tinnitus is not a life-threatening disease; however, it is usually accompanied by depression, anxiety, sleep disorder, and other emotional disorders [4] having considerable impact on the patients’ quality of life and causes social and economic burden [2].

Degeneration of the outer hair cells in the peripheral auditory system is known to be associated with tinnitus [5]. Recent studies have identified chronic and severe tinnitus as a consequence of neuroplastic alterations in the central auditory pathway and somatosensory changes [5]. However, the exact mechanism underlying subjective tinnitus remains unclear.

Currently used treatments for tinnitus include counseling, cognitive behavioral therapy, tinnitus retraining therapy, hearing aids, cochlear implants, and medications, based on the previously identified pathology of tinnitus [6, 7]. However, many patients with chronic or refractory tinnitus do not respond to these treatments [8]. Accordingly, there is a high demand for tinnitus treatment with alternative medicine, and acupuncture therapy is widely used in traditional Asian medicine treatments of tinnitus [8].

Many clinical studies have evaluated the efficacy of acupuncture for tinnitus [9‒12]. In acupuncture treatment, there are numerous details to be specified, including acupoint selection, types of needles, needle retention time, treatment intervals, and treatment duration. However, while the efficacy of acupuncture has been established in several systematic reviews, the differences in efficacy based on acupuncture characteristics have not been well documented [13‒15]. Additionally, there is considerable inter-study variability resulting from these specific acupuncture methods. Moreover, studies have investigated the effects of acupuncture, revealing that its efficacy is largely dependent on factors such as the number of treatment sessions per week, total treatment periods, stimulation frequency, and intensity [16], as well as the impact of acupuncture needle size on microperfusion [17]. Consequently, both clinicians in the actual practice of acupuncture and researchers designing clinical studies on acupuncture treatment often encounter difficulties in determining these aspects.

Scoping reviews are a relatively new approach that present an overview of a potentially large and diverse body of literature pertaining to a broad topic, whereas systematic reviews aim to collate empirical evidence from a relatively small number of studies pertaining to a focused research question [18]. They can report the types of evidence that address and inform practice in the field and the way in which the research has been conducted. For this reasons, there have been several scoping reviews that have reported detailed information on the acupuncture treatment for various disorders [19, 20]. Scoping reviews that explore the detailed evidence of acupuncture for tinnitus can also serve as precursors for conducting future clinical studies and systematic reviews. For the aforementioned reasons, this scoping review aimed to identify and analyze detailed information on the acupuncture treatment methods employed in clinical studies and provide useful information for practitioners, patients, and researchers.

The present review was prepared in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Extension for Scoping Reviews (PRISMA-ScR), a reporting system for scoping reviews. It was registered on the OSF, an international database of scoping reviews (https://doi.org/10.17605/OSF.IO/UEZ7H).

Database and Search Strategy

Domestic and international articles and studies published up to December 18, 2023, were targeted for a literature review. Two individual researchers (K.H.L. and J.H.K.) reviewed the extracted literature for the selection or exclusion of the searched literature. In the case of disagreements in the selection and exclusion process, the two researchers went through a discussion process, and one researcher (H.J.N.) determined the inclusion or exclusion of the literature.

The domestic database search was conducted using “acupuncture” and “tinnitus” as search keywords on the Korean Research Information Sharing Service (RISS [https://www.riss.kr]), Korea Institue of Oriental Medicine’s Oriental Medicine Advanced Searching Integrated System (OASIS [https://oasis.kiom.re.kr/]), and DataBase Periodical Information Academic (Dbpia [https://www.dbpia.co.kr/]).

The international database search was conducted on MEDLINE (PubMed [https://pubmed.ncbi.nlm.nih.gov/]), Embase (https://www.embase.com), Cochrane (https://www.cochranelibrary.com/), and China National Knowledge Infrastructure (CNKI) (https://www.cnki.net/). The search expressions used for the search are shown in Table 1.

Table 1.

Search strategy

MEDLINE (PubMed) 
 (((tinnitus[MeSH Terms]) OR (tinnitus[Title/Abstract]) OR (phantom sound*[Title/Abstract]) OR (ringing[Title/Abstract]) OR (buzzing[Title/Abstract])) AND ((acupuncture[MeSH Terms]) OR (acupuncture therapy[MeSH Terms]) OR (acupuncture point[MeSH Terms]) OR (acupuncture[Title/Abstract]) OR (acupoint[Title/Abstract]) OR (acupuncture[Title/Abstract]) OR (acupuncture therapy[Title/Abstract]) OR (acupuncture point[Title/Abstract]) OR (akupuncture[Title/Abstract]) OR (acupoint∗[Title/Abstract]) OR (Needling[Title/Abstract]) OR (Needle*[Title/Abstract])) 
Filters applied: Case Reports, Clinical Trial, Meta-Analysis, Observational Study, Pragmatic Clinical Trial, Randomized Controlled Trial, Review, Systematic Review, Humans 
Embase 
 #1 tinnitus OR (phantom AND sound*) OR ringing OR buzzing 
 #2 acupuncture OR (acupuncture AND therapy) OR (acupuncture AND point) OR acupoint OR acupuncture OR acupointp∗ OR needling OR needle* 
 #3 #1 AND #2 ([cochrane review]/lim OR [systematic review]/lim OR [meta analysis]/lim OR ([clinical trial]/lim OR ([observational study]/lim) 
Cochrane 
 #1 tinnitus 
 #2 phantom sound 
 #3 ringing 
 #4 buzzing 
 #5 #1 OR #2 OR #3 OR #4 
 #6 acupuncture 
 #7 acupuncture therapy 
 #8 acupuncture point 
 #9 acupoint* 
 #10 acupuncture 
 #11 needling 
 #12 Needle 
 #13 #6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 
 #14 #5 AND #13 
 *Filter: in Cochrane review 
CNKI 
 (TI, SU = “Tinnitus” OR TI, SU = “耳鸣”) AND (TI,SU,AB = “经穴” OR TI, SU = “针刺” OR TI, SU = “穴位” OR TI, SU = “针灸”) 
Korean Database (RISS, OASIS, DBPIA) 
 “Tinnitus” AND “Acupuncture” 
MEDLINE (PubMed) 
 (((tinnitus[MeSH Terms]) OR (tinnitus[Title/Abstract]) OR (phantom sound*[Title/Abstract]) OR (ringing[Title/Abstract]) OR (buzzing[Title/Abstract])) AND ((acupuncture[MeSH Terms]) OR (acupuncture therapy[MeSH Terms]) OR (acupuncture point[MeSH Terms]) OR (acupuncture[Title/Abstract]) OR (acupoint[Title/Abstract]) OR (acupuncture[Title/Abstract]) OR (acupuncture therapy[Title/Abstract]) OR (acupuncture point[Title/Abstract]) OR (akupuncture[Title/Abstract]) OR (acupoint∗[Title/Abstract]) OR (Needling[Title/Abstract]) OR (Needle*[Title/Abstract])) 
Filters applied: Case Reports, Clinical Trial, Meta-Analysis, Observational Study, Pragmatic Clinical Trial, Randomized Controlled Trial, Review, Systematic Review, Humans 
Embase 
 #1 tinnitus OR (phantom AND sound*) OR ringing OR buzzing 
 #2 acupuncture OR (acupuncture AND therapy) OR (acupuncture AND point) OR acupoint OR acupuncture OR acupointp∗ OR needling OR needle* 
 #3 #1 AND #2 ([cochrane review]/lim OR [systematic review]/lim OR [meta analysis]/lim OR ([clinical trial]/lim OR ([observational study]/lim) 
Cochrane 
 #1 tinnitus 
 #2 phantom sound 
 #3 ringing 
 #4 buzzing 
 #5 #1 OR #2 OR #3 OR #4 
 #6 acupuncture 
 #7 acupuncture therapy 
 #8 acupuncture point 
 #9 acupoint* 
 #10 acupuncture 
 #11 needling 
 #12 Needle 
 #13 #6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 
 #14 #5 AND #13 
 *Filter: in Cochrane review 
CNKI 
 (TI, SU = “Tinnitus” OR TI, SU = “耳鸣”) AND (TI,SU,AB = “经穴” OR TI, SU = “针刺” OR TI, SU = “穴位” OR TI, SU = “针灸”) 
Korean Database (RISS, OASIS, DBPIA) 
 “Tinnitus” AND “Acupuncture” 

CNKI, China National Knowledge Infrastructure; RISS, Korean Research Information Sharing Service; DBPI, DataBase Periodical Information Academic.

Eligibility Criteria

The studies and literature inclusion criteria for the present review were as follows: (1) clinical studies on patients with tinnitus; (2) studies that performed various acupuncture treatments, such as general acupuncture, electro-acupuncture, auricular acupuncture, burning acupuncture, warm needling, intradermal needling, and bloodletting therapy, as interventions for the treatment of tinnitus patients that have a clear reference to “acupoint” or “acupuncture point”; and (3) prospective experimental clinical studies, including single-arm trials, open-label randomized controlled trials (RCTs), and double-blind RCTs. The present review is not an investigation of the effectiveness of acupuncture treatment for patients with tinnitus but rather an analysis of acupoints. Therefore, studies including parallel treatments, such as herbal and western medicine, were included in the review.

After the initial selection of literature extracted using the search formula, (1) studies that were searched but the text could not be retrieved, (2) studies with unverifiable acupoints, (3) studies that used validated and broad questionnaire for the assessment of tinnitus severity (Tinnitus Handicap Inventory (THI), Tinnitus Functional Index (TFI), Tinnitus Questionnaire (TQ), Mini TQ, or Tinnitus Severity Index (TSI) [21, 22], and (4) articles deemed inappropriate by the researchers, such as laser acupuncture, retrospective study, and clinical trial reviews, were excluded.

Data Analysis

The final literature selected through the inclusion and exclusion processes was examined for basic study information, acupuncture treatment methods, evaluation methods, and treatment outcomes. Analysis of basic information, such as study design, country and language, year of publication, and participant characteristics, was conducted. Acupuncture treatment methods were analyzed according to the type of acupuncture, type of intervention, treatment of the comparison groups, utilization of acupoints and meridians, treatment duration and sessions, acupuncture duration, and needle type and depth.

Literature Search Results

The present study analyzes acupoints used for acupuncture treatment for tinnitus, with tinnitus being the target disease and the acupuncture procedure being the intervention. On domestic databases, 61 articles were searched on RISS, 16 on Oasis, and 15 on DBPIA. On international databases, 91 articles were searched on PubMed, 634 on Embase, 194 on Cochrane, and 1,210 on CNKI. Duplicate articles were excluded using the Endnote20 (Clarivate Analytics, London, UK) reference management program, and 2,221 articles were searched. Among the 2,221 articles, those that did not target patients with tinnitus, those that did not use acupuncture treatment as the intervention, and those that were review or protocol papers and not clinical trials were subsequently excluded by checking the titles and abstracts, yielding 562 articles. Among the 562 articles, those from which the main text could not be retrieved, those with unverifiable acupoints, those that did not conduct the validity assessment using THI, TFI, THS, TQ, mini TQ, and TSI scales, and those deemed inappropriate by the researchers, such as laser acupuncture and clinical trial reviews, were excluded. After excluding seven identical studies examining the original versions of Chinese articles published in English, 106 articles were selected (Fig. 1).

Fig. 1.

Flowchart of review.

Fig. 1.

Flowchart of review.

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Basic Information

Study Design

The 106 studies included in this review consisted of 11 single-arm trials, 90 open-label RCTs, and 5 double-blind RCTs. The details of each research method are described in Additional tables (see online suppl. additional file 1; for all online suppl. material, see https://doi.org/10.1159/000538236).

Countries and Languages of Literature

Ninety-five out of 106 studies were conducted in China, followed by three in Korea, two in Iran, one in the UK, one in Turkey, one in Taiwan, one in Brazil, one in Germany, and one in Egypt. Ninety-three studies were reported in Chinese, and 13 studies were in English (see online suppl. additional file 1).

Year of Publication

Forty studies were published after 2020: 65 between 2010 and 2019, and one between 2000 and 2009 (see online suppl. additional file 1).

Study Participants

The number of study participants varied from 6 to 384, including those in the control group, averaging approximately 72.3 participants. When the duration of illness was considered in participant inclusion criteria, 29 studies included chronic patients with tinnitus for 3 months or longer. Eight studies only targeted patients with acute tinnitus lasting less than 3 months. Twenty-seven cases targeted patients regardless of acute or chronic tinnitus, and 42 cases did not include tinnitus duration (see online suppl. additional file 1).

Acupuncture Treatment Methods

Type of Acupuncture Used in Treatment Group

Regarding the acupuncture treatment method, 80 studies used standard acupuncture, 10 used electro-acupuncture, four used warm needling, three used standard and electo-acupuncture, three used standard and auricular acupuncture, two used intradermal needling, three used bloodletting therapy and standard acupuncture, and one used burning acupuncture and standard acupuncture.

Types of Intervention Accompanied with Acupuncture in the Treatment Group

Of the 106 studies, 35 studies allowed other treatments for tinnitus in the acupuncture treatment group. Allowed treatments were: herbal decoctions (n = 11), western medicine treatments (n = 9, vitamins, cobalt amines, or western medicine), moxibustion (n = 7), narrow-band noise masking and cognitive behavioral therapy (n = 2), repetitive transcranial magnetic stimulation (n = 2), massage and herbal decoction (n = 1), acupoint pressure and external herbal patch (n = 1), physical therapy (n = 1), cupping (n = 1), and breathing regulation method (n = 1).

Type of Intervention Used in the Comparison Groups

Of the 94 open-arm RCTs, the types of treatments used in the comparison group were: needled the identical acupoint using different acupuncture treatments (n = 42), western medicine treatments (n = 20), herbal decoctions (n = 12), needled a different acupoint (n = 13), electro-acupuncture (n = 5), shallow acupuncture (n = 2), warm needling (n = 1), physical therapies (n = 2, laser, ultrashort wave, and TENS), overall care (n = 1), and no-treatment (n = 1).

Utilized Acupoints and Meridians

In the 106 articles included in this study, a total of 119 acupoints were used 1,136 times, including duplicates and excluding auricular acupoints and extra points (EX), which were unclear due to the lack of use of standard acupoint names. The most commonly utilized acupoints were TE17 (n = 90), followed by GB2 (n = 88), SI19 (n = 82), TE21 (n = 70), TE3 (n = 58), KI3 (n = 48), LR3 (n = 40), ST36 (n = 37), GB20 (n = 36), TE5 (n = 32), and BL23 (n = 30) (Fig. 2; see online suppl. additional file 2). Among the 15 meridians, the most utilized meridians were the triple energizer meridian (TE) (see online suppl. additional file 3).

Fig. 2.

Location and frequency of top 20 acupoint (Chinese name, standard name, frequency).

Fig. 2.

Location and frequency of top 20 acupoint (Chinese name, standard name, frequency).

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Treatment Duration and Sessions, Acupuncture Duration, Needle Type, and Needling Depth

The number and frequency of treatments in 103 out of the 106 included studies were recorded to examine treatment duration and the number of sessions. Of these, 61 studies had a treatment duration of 20–39 days, 19 of fewer than 20 days, 15 of 40–59 days, and four of more than 60 days. In double-blind RCTs, the total treatment duration was less than 20 days for three out of five studies, while two studies had durations of 20–39 days.

Regarding the number of acupuncture treatments, 10 cases provided less than 10 sessions, 39 cases provided 10 to 19 sessions, 36 cases provided 20 to 29 sessions, and 18 cases provided more than 30 sessions. Of the 106 articles reviewed, 100 specified acupuncture duration, and six did not specify. The most common acupuncture duration was an average of 30 min for 70 studies, followed by 20 min for 18 studies, 10 min for two, and 40 min for three studies. In double-blind RCTs, all five studies exclusively reported 10–19 sessions, Eighty-six out of 106 articles indicated the thickness and length of needles used for treatments, and 23 did not. The most commonly used needle dimensions were 0.30 mm × 40 mm for 35 studies, followed by 0.25 mm × 40 mm for 19 studies, 0.35 mm × 40 mm for 16 studies, 0.30 mm × 25 mm for 14 studies, and 0.25 mm × 25 mm for 13 studies. There were 17 other needle types used in 22 studies. In double-blind RCTs, among the three studies specifying needle types, one utilized needles with dimensions of 0.25 mm × 25 mm, while the other two employed needles with dimensions of 0.25 mm × 40 mm.

Needling depth was mentioned in 83 of 106 articles and was expressed in the traditional units of length, chon (寸, chon), and mm. Of these, units of chon were converted to mm to confirm the mean depth of needling mentioned in the articles. The highest number of cases were 37 cases in which the needling depth was 30 mm to less than 50 mm, 28 cases of 20 mm to less than 30 mm, ten cases of 10 mm to less than 20 mm, three cases of 50 mm or more, and five cases of less than 10 mm. In double-blind RCTs, among the two studies specifying needle depth, one applied needles at a depth of less than 10 mm and the other at 10–19 mm (Fig. 3).

Fig. 3.

Details of acupuncture treatment methods.

Fig. 3.

Details of acupuncture treatment methods.

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Treatment Outcomes

Of the 106 studies, 105 confirmed improvement in patients’ symptoms. Only one of open-label RCTs [23] found no statistically significant changes (see online suppl. additional file 1).

Previous systematic reviews have focused on identifying whether acupuncture is effective in treating tinnitus [13‒15]. In this study, we aimed to understand the characteristics of acupuncture and the acupoints used in clinical studies of acupuncture treatments for tinnitus and to provide useful information for more effective acupuncture treatment in actual clinical practice and for designing clinical studies of tinnitus. To this end, the 106 articles reviewed consisted of 11 single-arm trials, 90 open-label RCTs, and 5 double-blind RCTs.

Acupuncture is a treatment method used not only in traditional Chinese medicine but also in traditional Korean medicine and Western countries, and it is based on both traditional concepts and modern human anatomy and physiology. Only 17% of these studies were conducted outside of China. In addition, only one study included >100 participants. These results indicate that data accumulation from large-scale RCTs based on various theories in more diverse countries is required in the future.

The acute phase of tinnitus is interpreted as the leading cause of damage to the cochlea due to noise, ototoxicity, and neck trauma, according to the hypothesis of hearing impairment of peripheral cochlear origin. However, although this mechanism may play a role in the early stages of the development of tinnitus, according to the results of studies that reported that tinnitus occurs even after the removal of auditory nerves, changes in the central nervous system are recognized as the primary mechanism of occurrence in the development and maintenance of tinnitus [1]. Therefore, the duration of tinnitus was a crucial factor among the inclusion criteria for the study participants. Still, there were 69 cases in which the duration of symptoms was not distinguished or not included as a participant inclusion criterion. It was determined that it is necessary to properly specify tinnitus duration to improve the quality of tinnitus research in the future.

Manual acupuncture was the most common type of acupuncture and was used in 80 studies. Despite a large number of studies on manual acupuncture, well-designed RCTs are lacking. It is widely known that the accumulation of weak evidence is not a substitute for strong evidence. As described earlier, if a large-scale RCT is conducted and evidence for manual acupuncture improves, RCTs for other types of acupuncture will be performed more often.

In clinical practice, acupuncture uses a combination of local and distant point stimulation for tinnitus [24]. Local points are points adjacent to uncomfortable sites, and distant points are located further away from uncomfortable sites. Local point stimulation is believed to act through peripheral mechanisms, such as vasodilation and segmental inhibition, whereas distant point stimulation involves central mechanisms [25]. In this study, the most frequently used acupoints were local points around the ear (TE17, GB2, SI19, and TE21); other acupoints around the ear were also frequently used (GB20, GV20, and GB8). The next most-used acupoints were distant points that were used to clear wind and heat (TE3 and TE5), tonify qi and support the action of the spleen (ST36, ST40, SP6, LI4, CV4, and CV6), clear heat in the liver and gallbladder (LR3, GB43, and GB40), and nourish the kidney (BL23 and KI3). These results indicate that both local and distant acupoints can be used simultaneously in the treatment of tinnitus.

In the total treatment duration, the majority of cases in the entire study ranged from 20 to 39 days, constituting 61 studies. However, within the subset of double-blind RCTs, the total treatment duration of three out of five studies was less than 20 days, indicating a relatively shorter treatment duration in double-blind RCTs compared to other studies. Regarding the number of treatment sessions, in the overall research, there were 39 cases with 10–19 sessions and 36 cases with 20–29 sessions, indicating a comparable distribution. In contrast, among double-blind RCTs, all five studies exclusively reported 10–19 sessions, suggesting a tendency toward fewer treatment sessions. It is hypothesized that the challenges associated with conducting double-blind RCTs, such as the implementation of sham acupuncture or maintaining blinding until the end of the study, contribute to a reduction in both total treatment duration and the number of treatment sessions compared to open-arm RCTs.

In terms of needle type, the most commonly used needle dimensions were 0.30 mm × 40 mm for 35 studies. However, in double-blind RCTs, among the three studies specifying needle types, one utilized needles with dimensions of 0.25 mm × 25 mm, while the other two employed needles with dimensions of 0.25 mm × 40 mm, indicating a tendency toward finer needles in double-blind RCTs. Additionally, concerning needle depth, in the entire study, the majority involved needling to a depth of 30–49 mm (37 cases), followed by 20–29 mm (28 cases). However, within the subset of double-blind RCTs, among the two studies specifying needle depth, one applied needles at a depth of less than 10 mm and the other at 10–19 mm. This is considered due to the establishment of sham acupuncture in the control group of double-blind RCTs by either not penetrating the skin or placing the needles very shallowly. Consequently, there is a concern that the use of thicker needles or an increase in needle depth within the acupuncture group may lead to a noticeable difference in sensation compared to sham acupuncture, making participant blinding challenging. This tendency may explain the preference for finer needles and shallow needle depth in double-blind RCTs.

Initially published in 2001, the STRICTA Reporting Guidelines were created to improve interpretation accuracy and reproducibility by increasing the completeness and transparency of intervention reporting in comparative clinical trials of acupuncture [26, 27]. It includes the following six factors: “grounds for acupuncture,” “detailed contents of acupuncture,” “treatment contents,” “other components of treatment,” “background of practitioner,” and “control group and comparative intervention.” However, none of the 106 studies included all STRICTA factors. Due to the lack of adherence to these guidelines, most articles are missing techniques or have only roughly categorized the procedures. In the present study, the analysis of treatment outcomes revealed improvement in all cases, except for one study, out of a total of 106 studies, including five double-blind RCTs. The remarkably high improvement rate of 99% was demonstrated. It is worth noting that single-arm studies and open-arm RCTs may exhibit an overly measured improvement rate due to the potential presence of bias. In double-blind RCTs, there is also a possibility of distorted improvement rates due to bias stemming from non-adherence to STRICTA guidelines. This suggests that researchers planning future acupuncture treatments for tinnitus will need to adhere to STRICTA.

This review had several limitations. First, the overall quality of the included studies, including the double-blind RCTs, was generally poor. They lacked crucial details related to randomization, recruitment, blinding, and measurement. Additionally, they did not include grounds for acupuncture treatment, lacked results of long-term follow-up, and had small sample sizes. Second, most included studies were published in China. As a result, the treatment methods used in other countries could not be thoroughly analyzed in this study.

In brief, the present scoping review provides detailed information on the acupuncture treatment methods used in clinical studies. This study will enable future acupuncture studies on tinnitus to perform more effective and standardized acupuncture treatments in selecting acupoints and procedures and inform clinicians and students of more effective acupuncture treatments.

We conducted a scoping review to identify detailed information on acupuncture treatment methods used in clinical studies and to provide useful information for practitioners, patients, and researchers. We included 95 articles. There were 15 single-arm trials, 73 open-label RCTs, and 7 double-blind RCTs. We investigated basic and detailed information on the acupuncture treatment methods, assessment methods, and study outcomes. This study will enable future acupuncture studies on tinnitus to perform more effective and standardized acupuncture treatments in selecting acupoints and procedures. Additionally, it informs clinicians and students about more impactful acupuncture strategies for addressing tinnitus.

An ethics statement is not applicable because this study is based exclusively on published literature. It was registered on the OSF, an international database of scoping reviews (https://doi.org/10.17605/OSF.IO/UEZ7H).

The authors declare no conflicts of interest.

The authors received no financial support for the research, authorship, and/or publication of this article.

Hae Jeong Nam conceived and designated the study. Keun Hee Lee and Jaeho Kim did the systematic search, study selection, and data extraction. Keun Hee Lee and Min Hee Kim conducted the statistical analyses and wrote the manuscript with interpretation. Keun Hee Lee, Min Hee Kim, Jaeho Kim, and Hae Jeong Nam conducted critical revision. All authors reviewed and approved the final manuscript.

Additional Information

Keun Hee Lee and Min Hee Kim contributed equally to this work (co-first authors).

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

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