Scalp acupuncture (SA) is an acupuncture modality that involves the insertion of acupuncture needles into the loose areolar tissue between the epicranial aponeurosis and pericranium [1]. The stimulation of certain areas on the scalp by inserting acupuncture needles modulates the activity of the corresponding zones in the brain, allowing the application of SA in the treatment of pain and a wide spectrum of neurological disorders of various genesis [2,3]. The practical application of SA does not necessitate a specialized treatment environment or specialized equipment. Additionally, SA is a versatile treatment method suitable for patients of all ages, including children as young as three years old. [3-5]. SA was initially developed in the 1950s in China by combining traditional oriental medical knowledge with modern Western anatomy and neuroscience [4,6-8]. SA as an independent system was separated from traditional Chinese acupuncture at the beginning of the 1970s [8]. SA, as included in the Standard International Acupuncture Nomenclature (SIAN) [9], is based on the work of Dr. Jiao ShunFa. Dr. Jia’s SA system was among the several SA systems that emerged during the 1950-1980s [1,4]. The entire body’s physiology and symptoms can be influenced through SA; therefore, SA can be defined as MicroSystem (MS) acupuncture [6,7]. Generally, standard treatment protocols for specific conditions are created within one SA system and replicated for identical cases [1,4,6,10,11]. However, the treatment protocols are unique for every SA system, and there are no known standard protocols with consistent therapeutic outcomes that are universally applicable to the entire scope of SA.

Systematic reviews (SR) and meta-analyses (MA) inform evidence-based health policies [12]. Furthermore, evidence synthesis and secondary analysis guide clinical decision-making [13,14]. The National Institute for Health and Care Excellence (NICE) suggests that imprecision as well as “wide variation in the types of interventions being applied within the evidence” are among the limitations leading to the low quality of evidence on acupuncture and the consequent delay in the validation of the effectiveness of acupuncture techniques [15].

The variations and inconsistencies among SA systems in the absence of a unified standard have been recognized by many authors as factors interfering with the research on SA and its clinical application. The presence of multiple types of SA therapies causes clinical heterogeneity, and the mean evidence on SA is insufficient to justify clinical recommendations [16]. Kim et al. [17] and Lee et al. [18] highlighted that the irregularities in the therapeutic methods used for SA prevent the pooling of the effects of various SA types in meta-analyses. They proposed that the establishment of standardized treatment methods is essential for improving the quality of SA studies. Qiang et al., You et al., and Zhang et al. [19-22] concluded that the unification of SA points and the standardization of SA treatment methods and protocols are needed for clinical trials to effectively inform clinical practice.

Several authors have attempted to address the heterogeneity of SA methods. An [23] divided the locations of SA points into two categories. Wang et al. [24] examined SA systems that could be used in the treatment of post-stroke hemiplegia and concluded that the selection of acupoints is complicated and requires further research. More recently, Xu et al. [25] analyzed literature on the main Chinese schools of scalp needling. They suggested that needling areas should be based on clinical and experimental evidence and an optimal scheme of SA should be created; however, no synthesis was conducted. The heterogeneity of SA systems affects the quality of evidence synthesis and analysis and, consequently, the progression of SA to become a treatment modality acknowledged by Western medicine and included in healthcare policies.

The identification of the range of existing systems of SA published in English, searching for the common features, including anatomical and clinical characteristics, and building a framework of SA systems, may contribute to the process of standardizing SA. This will create a base for better quality future secondary research on this intervention. Additionally, the synthesis of information on the anatomy, clinical application, and general features of various SA systems might be a useful reference for acupuncture practitioners, policymakers, and patients. Scoping Review (ScR) was chosen as the methodology suitable for reviewing large bodies of literature on a given topic [26], identification and mapping of the types of evidence available in a given field, clarification of key concepts or definitions in the literature, identification of key characteristics related to a concept, and identification and analysis of knowledge gaps [27].

This comprehensive ScR aimed to identify the range of existing SA systems, systematically collect and summarize information on their general, anatomical, and clinical application characteristics, and build an anatomical and clinical framework of existing SA systems.

A preliminary search for existing ScRs and SRs on SA systems was conducted in August 2020 using the biomedical databases PubMed, PubMed Central (PMC), Europe PubMed Central (Europe PMC), Cochrane Library, International Prospective Register of Systematic Reviews (PROSPERO), The Joanna Briggs Institute (JBI) Evidence Synthesis, and NICE Evidence Search. Six protocols for SR and MA and 13 SRs and MAs were identified. An additional search in September 2022 identified one SR, two MAs, and one SR and MA (Supplementary material, Table S1). There were no ScRs or SRs published or in progress that addressed the topic of this review.

1. Scoping review

This ScR employed the methodological framework proposed by Arksey and O’Malley [26] and developed further by the JBI [28,29]. The protocol for this ScR was not registered; however, rigorous evidence synthesis was ensured by strict adherence to the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) [29] during both review planning and conduct.

2. Inclusion criteria

Data source identification and inclusion were based on the Population, Concept, and Context (PCC) criteria [29].

1) Population

This ScR included publications that involved human participants with any health condition treated using SA.

2) Concept and context

The core concepts examined were the name of the SA system and its general, anatomical, and clinical application characteristics. The general characteristics included the year and country of development and foundational concepts and theories. The anatomical characteristics consisted of a description of anatomical features on the locations of the SA system areas. The clinical application characteristics included indications for the use of SA system areas. The research methodology of the included literature was not the area of interest of this review. To identify evidence available from the time of establishment of the SA concept to the present time, the literature published between 1970 and January 2021 was included. The search was re-run in September 2022 to update the results.

3) Types of data source

The following data sources were considered for this ScR: published study protocols and qualitative, quantitative, and mixed-method studies of any design, as well as gray literature. Books, full-text papers, and abstracts available in English were selected for inclusion. The lack of time and resources for translation limited the consideration of publications in other languages. Only publications with detailed information on anatomical and clinical characteristics of the named SA systems were selected during the last phase of the screening.

3. Search strategy

Publications were identified using JBI’s [29] three-step search strategy. An initial search identified the following keywords from text words contained in titles, abstracts, and index terms:

• -

  Scalp acupuncture,

• -

  Head acupuncture,

• -

  Scalp AND Acupuncture,

• -

  Acupuncture therapy,

• -

  Scalp acupuncture treatment,

• -

  Scalp needle,

• -

  Skull acupuncture,

• -

  Suture acupuncture,

• -

  Cranial acupuncture,

• -

  Cephalic acupuncture,

• -

  Scalp electroacupuncture,

• -

  Scalp penetration acupuncture,

• -

  Head acupoints,

• -

  Scalp acupuncture points,

• -

  Scalp AND Acupuncture therapy,

• -

  Scalp acupoints,

• -

  Jin’s three-needle therapy.

These keywords were used for the second step of the search, which was performed across major bibliographic citation databases: PubMed, PMC, Europe PMC, Cochrane Library, The Database of Abstracts of Reviews of Effects (DARE), PROSPERO, Allied and Complementary Medicine Database (AMED), Alternative Health Research database (Alt HealthWatch), and Acudoc2 (a bibliographic database specialized in acupuncture and Chinese Medicine research). Journals and additional sources were searched for the terms [scalp acupuncture] and [head acupuncture]. To avoid missing papers due to the vague definition of the SA system in titles or abstracts, it was decided that the search must be of high sensitivity. The search strategy is shown in Supplementary material, Table S2. Searches were performed by one author between December 2020 and January 2021. The reference manager ‘Mendeley’ [30] was used for the management of search results.

Titles and abstracts were screened after duplicate removal and, to avoid omissions, the screening was performed twice by a single author. Papers eligible for inclusion were selected and reassessed to identify SA systems. Data on publications and SA were extracted into a table and arranged according to the name of the SA system. The selected literature was reexamined for the presence of detailed information on the identified SA systems, and a further search was performed through two major databases, Web search and Google Scholar, using the (name of the SA system identified in the second step) as a search term.

Ten authors of papers were contacted via email for additional information.

4. Data extraction

Data extraction was performed by one author. General data on each SA system, as well as data on their anatomical and clinical application characteristics, was extracted into data extraction charts. Pictorial information on the location of SA areas, verbal description of SA areas, and information on the clinical application characteristics were extracted separately for each SA system.

5. Data analysis and synthesis

Data on the general characteristics of SA systems were examined for commonalities and then combined. Following the JBI guidelines for ScRs [29] and to consolidate the complex and variable characteristics of SA systems [31], the principles of framework synthesis were applied for data analysis. Pictorial and charted data were arranged against an a priori framework following a pragmatic “best fit” approach [32]. The Standard International Acupuncture Nomenclature Scalp Acupuncture (SIANSA) [9,33,10] was used for the identification of a priori themes [34] because it is the most commonly used conceptual model of SA and is also accepted by the World Health Organization (WHO).

The GNU Image Manipulation Program (GIMP) [35] was used to superimpose images representing the anatomical characteristics of SA systems against pictures representing the anatomical locations described by the SIANSA. Simultaneously, written descriptions of the anatomical and clinical application characteristics were charted, examined for correlations, and sorted against those defined by the SIANSA. Subsequently, areas of SA systems equivalent to the SIANSA lines were scrutinized for similarities and interconnections of their clinical characteristics with clinical indications of the corresponding SIANSA lines. Data analysis was performed by a single author.

6. Ethics

This research project received full ethical approval from the Northern College of Acupuncture (NCA) Research Ethics Committee on 9 November 2020. The authors complied with the NCA Research Integrity Statement, the Declaration of Helsinki Protocols, and the General Data Protection Regulations at all times.

1. Search results

The search and selection process is presented using a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart (Fig. 1) [36]. Database, journals, and other source searches were conducted between 10 December 2020 and 18 January 2021. The deliberate high sensitivity of the search strategy provided an extensive range of literature and 47,296 records after duplicate removal. Following title and abstract screening, 270 titles were examined based on the inclusion criteria, and 33 SA systems and methods were identified as a result. As SIANSA is the most well-documented SA approach, it was chosen as an a priori framework for this review and, consequently, 55 studies on the SA system were excluded. Furthermore, 72 papers were excluded owing to the lack of detailed information on SA systems, and two animal studies and 33 titles that did not satisfy the intervention criteria were also excluded. Regrettably, five relevant books could not be obtained for this review. Ten authors were contacted to provide information on the English-language publications on the SA system they used in their research; although two authors responded, they could not provide the requested information. There was not enough information available in the English language on 14 of the SA systems that were to be included (Supplementary material, Table S3). The additional search in September 2022 was run using PubMed, and 21 titles were identified; however, no new SA systems or further information on previously found SA systems were obtained.

Figure 1. PRISMA flow-chart for the scoping review process [36].

2. Characteristics of included publications

The analysis and framework synthesis of 19 SA systems was based on 87 publications included in this ScR. The publications comprised 36 full-text articles, 42 abstracts (with comprehensive illustrations of the SA system characteristics), eight books, and one website publication.

Most publications (66 titles or 76% of the total publications) included in this review were from China. Other articles originated from Japan (two), Korea (three), Turkey (one), the UK (one), and the USA (three). The books included in this review were published in China (two), Switzerland (one), the UK (two), and the USA (three), and one publication was from a website in Canada. Table 1 shows the general characteristics of the included publications.

SA = scalp acupuncture; TCM = Traditional Chinese Medicine..

&md=tbl&idx=1' data-target="#file-modal"">Table 1

General characteristics of all publications included in ScR.

SA system (year of development) country of development	Foundational concepts and theories for SA system	Publication author (year) country	Publication type [ref]
Standard International Acupuncture Nomenclature Scalp Acupuncture (SIANSA) (1991) WHO Scientific Group	ShunFa Jiao’s SA	World Health Organization (1991) Geneva	Full-text article [9]
		World Health Organization (1993) Regional Office for the Western Pacific, Philippines	Full-text article [33]
		Nie (2019) UK	Book [10]
Jiao’s SA (1970s) China	TCM, Neuroanatomy and Neurophysiology of CNS	Jiao (1987) China	Book [37]
		Jiao (1997) China	Book [38]
Chinese SA (ChSA) (1980-1990s) China, USA and Europe	TCM, SIANSA, Neuroanatomy and Neurophysiology of CNS	Hao and Hao (2011) USA	Book [1]
		Wang (2021) Switzerland, UK	Book [11]
Yamamoto New Scalp Acupuncture (YNSA) (1970s) Japan	TCM theory, Somatotopic representation of the body on scalp different from Chinese SA	Feely (2011) Germany, USA	Book [6]
Zhu’s SA (1980-1990s) China, USA	TCM theory, and clinical experience	Zhu (2007, 2017) USA	Book [39]
Functional SA (FSA) (2019) USA	Neuroscience, Psychology, and evidence-based acupuncture research	Angelone (2019) UK, USA	Book [40]
Traditional Chinese Medicine Scalp Acupuncture (TCMSA) (400 BC) China	TCM	TCMSA, Aggregated (Supplementary material, Table S4, S6) (2000-2021) 58 titles from China, USA, Japan, Korea, Turkey, UK	Abstracts - 33, Full-texts - 25
Penetrating SA (PSA) (400 BC) China	TCM	Penetrating SA, Aggregated (Supplementary material, Table S5, S7) (2000-2021) 14 titles from China and Korea	Abstracts - 11, Full-text - 3
Bagua SA (1990s) China	The concept of Baguà drawn from ancient philosophies detailed within the I Ching/Yi Jing, The Book of Changes	Qin and Zhou (2006) USA	Full-text article [41]
Cranial Sutures SA (-) China	Cranial anatomy, Neurophysiology and Neuropathology	Yu et al. (2002) China	Abstract [42]
		Wang et al. (2014) China	Full-text article [43]
Temporal Three-Needle Therapy (2000s) China	Jin’s three-needle therapy	Zhao et al. (2020) China	Full-text article [44]
Parietal Acupoint Therapy (PAPT) (2002) Japan	YNSA and new somatotopic representation of the body on scalp	Aoyama et al. (2017) Japan	Full-text article [45]
Cranial Base SA (400 BC) China	TCM	You et al. (2018) China	Abstract [46]
Broca area SA (2000s) China	Neuroanatomy, Neurophysiology	Jiang et al. (2015) China	Abstract [47]
Pyramidal Decussation SA (2000s) China	Cranial anatomy and TCM points anatomy, Neuroanatomy, Neurophysiology	Wang et al. (2011) China	Abstract [48]
Cluster SA (1990s) China	TCM, Neurophysiology, Neuropathology and Clinical experience	Wang et al. (2018) China	Full-text article [49]
		Zhang and Hu (2012) China	Full-text article [50]
Qin’s Eight Needles (2000s) China	TCM theories of channels, Clinical experience	Dong and Cui (2014) China	Abstract [51]
Fang’s SA (1970s) China	TCM theory, Body holographical representation on scalp, Clinical experience	Website of the “Dr. Che Walton NatHealing Centre” (2021) Canada	Full-text article, Copies of publication on website [52]
		Zhou et al. (2020) China	Full-text article [53]
Neuroimaging SA (2010-2020s) USA	SA technique, Neuroimaging (Magnetic resonance imaging, Positron emission tomography and Diffusion tensor imaging), Neurophysiology	Cao et al. (2020) USA	Full-text article [3]

SA = scalp acupuncture; TCM = Traditional Chinese Medicine..

The findings from the 87 included publications are presented below.

1. SA systems

The 19 SA systems were:

• -

  Standard International Acupuncture Nomenclature SA (SIANSA) [9,10,33];

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  Jiao’s SA [37,38];

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  Chinese SA (ChSA) [1,11];

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  Yamamoto New SA (YNSA) [6];

• -

  Zhu’s SA [39];

• -

  Functional SA (FSA) [40];

• -

  Traditional Chinese Medicine (TCM) SA (TCMSA) (Supplementary material, Table S4, S6);

• -

  Penetrating SA points (PSA) (Supplementary material, Table S5, S7);

• -

  Bagua SA [41];

• -

  Cranial Sutures SA [42,43];

• -

  Temporal Three-needle Therapy [44];

• -

  Parietal Acupoint Therapy (PAPT) [45];

• -

  Cranial Base SA [46];

• -

  Broca area SA [47];

• -

  Pyramidal Decussation projection SA [48];

• -

  Cluster SA (Yu’s SA) [49,50];

• -

  Qin's Eight Scalp Needles [51];

• -

  Fang’s SA [52,53];

• -

  Neuroimaging SA [3].

Combinations of the TCM acupuncture head points are often referred to in the literature as SA. To identify the full range of the SA phenomenon, TCMSA and PSA were included in this review as two distinct systems. To analyze common patterns in the use of TCM points on the scalp, data from publications on TCMSA and PSA (58 titles for TCMSA and 14 titles for PSA) were grouped as two distinct SA systems (Supplementary material, Table S4-S7).

2. Year of publication

The distribution of sources by the year of publication is shown in Fig. 2. The first SA publication in English was a translation of the work of Dr. Jiao ShunFa dated 1987. It was followed by the WHO publications of SIANSA in 1991 and 1993, and another translation of Dr. Jiao ShunFa’s work in 1997. The first trials on SA were published after 2000, starting from TCMSA, PSA, and Cranial Sutures SA. The volume of publications increased drastically after this, with 16 publications during 2005-2009, 36 during 2010-2014, 22 during 2015-2019, and 12 during 2020-2021.

Figure 2. Distribution of publications by year. SIANSA = Standard International Acupuncture Nomenclature SA; ChSA = Chinese SA; YNSA = Yamamoto New SA; FSA = Functional SA; TCMSA = Aggregated TCM SA points; PSA = Aggregated Penetrating SA points; CS SA = Cranial Sutures SA; TTNT = Temporal Three-needle Therapy; PAPT = Parietal Acupoint Therapy; CB SA = Cranial Base SA; BA SA = Broca area; PDP SA = Pyramidal Decussation projection SA; QESN = Qin’s Eight Scalp Needles; NI SA = Neuroimaging SA.

3. Foundational concepts and theories

Nearly all SA systems, except TCMSA and PSA, were developed since 1970. Fig. 3 shows the distribution of SA systems according to their foundational concepts and theories. TCMSA and PSA do not represent contemporary SA and are based solely on Chinese medical theory and practical knowledge. Three other systems based only on the TCM theory are Cluster SA, Qin’s Eight Needles, and Cranial base SA. Five SA systems (SIANSA, Jiao’s SA, Chinese SA, Temporal Three Needle Therapy, and FSA) are rooted in the 2,400-year-old TCM and conjoined with the modern understanding of neurophysiology and neuroanatomy. Five SA systems (Neuroimaging SA, Pyramidal Decussation projection SA, Broca area SA, Cranial Sutures SA, and FSA) were developed based on the neuroanatomy and neurophysiology of the Central Nervous System (CNS) and the interconnection of the scalp with the underlying zones of the brain. YNSA, Zhu’s SA, PAPT, and Fang’s SA use varying somatotopic representations of the body on the scalp as their theoretical basis. The BaGua concept from the I Ching philosophy was applied to create Bagua SA.

Figure 3. SA systems arranged according to their foundational concepts and theories. SA = scalp acupuncture; TCM = Traditional Chinese Medicine; SIANSA = Standard International Acupuncture Nomenclature SA; YNSA = Yamamoto New SA.

4. Anatomical characteristics

The direct superimposition of the images representing SA systems for the pictorial analysis of anatomical characteristics was hindered by artists’ differences in the vision of the head shape and anatomy, the angle of head tilt and rotation, and the location of SA areas. To overcome this issue, pictorial representations of all SA systems were compiled with the use of the model of the scalp drawn by Moyee Siu [39] based on pictorial and verbal descriptions of the anatomical characteristics of SA systems. Despite the efforts to standardize the pictorial representation of the anatomical features of SA, verbal descriptions based on cranial anatomy and TCM acupoints appeared to be more detailed and reliable.

Cranial anatomy was used for the identification of the needling zones to various extents by all SA systems. TCM acupuncture points were the main landmarks on the scalp in SA systems that utilized the TCM theory, although the measurements applied for locating these points were different. The measurement systems employed included the bone proportional cun or inch measurement method, the finger cun measurement method, or the metric system. There was a tendency to use TCM points as landmarks without applying the TCM theory, typically for newer SA systems based on neuroscience (Fig. 3). SA systems based on scalp somatotopic body representation utilized their own guiding points.

5. Clinical characteristics

The treatment of neurological dysfunctions, regardless of their genesis, was the most common clinical indication for SA application in the publications reviewed here. These included pain, motor and sensory disorders, visual, hearing, and balance dysfunctions, and thoracic and abdominal organ diseases with a central involvement. Another group of indications for SA treatment included cognitive, mental, psychological, and emotional disorders, such as insomnia, depression, anxiety, and poor memory and concentration. Most SA systems were used in the treatment of multiple health conditions, and the treatment protocol for a condition was usually disease-specific within a particular SA system.

The group of SA systems based on neuroscience tended to treat limited conditions specific to the location of the stimulated scalp zone. Temporal Three-needle Therapy, Broca area SA, Pyramidal Decussation projection SA, and Neuroimaging SA were used to treat motor dysfunction, speech problems, cerebellar disorders, and particular diseased areas of the CNS (chosen with the help of imaging technologies), respectively.

Although SA systems are used for the treatment of similar neurological conditions, they present a heterogeneous phenomenon due to the differences in their underlying theories and anatomical diversity. To bring these SA systems together under a unified framework, a detailed examination of their anatomical and clinical attributes was undertaken. The charted characteristics of the identified SA systems were analyzed against an a priori framework using the principles of framework synthesis.

Despite every SA system discussed here having many anatomical characteristics corresponding to the a priori framework, significant discrepancies in the methods of identifying anatomical landmarks impeded their use as a foundation for synthesis. A detailed examination of the clinical indications of SA systems showed a low degree of correspondence with anatomical features but a close correlation with the theoretical bases of SA systems. Considering the significant complexity of the approach used for locating anatomical landmarks and the dependence of treatment indications on the theoretical origins of SA systems, the authors were unable to build an SA framework solely based on the grounds of SA anatomy and clinical indications.

1. Synthesis based on anatomical characteristics

The anatomical characteristics of SIANSA lines and their clinical indications were used as the key elements for synthesis and served as the principal components for all SA systems, thereby providing a common ground for creating an SA framework. The anatomical positioning of SIANSA lines on the scalp was described with the use of TCM acupuncture points and cranial anatomical landmarks [9:pp. 16-24, 33:pp. 11-20]. Pictorial and verbal descriptions of the anatomical components of SA systems were systematically categorized based on their correspondence with SIANSA lines in the scalp regions they shared. In cases where an SA system had distinct areas that did not align with SIANSA lines, the areas were noted separately for incorporation into the SA framework. A quantitative representation of the synthesis of anatomical and clinical characteristics in comparison to SIANSA is presented in Table 2.

SA = scalp acupuncture; SIANSA = Standard International Acupuncture Nomenclature Scalp Acupuncture; TCM = Traditional Chinese Medicine; YNSA = Yamamoto New Scalp Acupuncture..

&md=tbl&idx=2' data-target="#file-modal"">Table 2

Quantitative representation of corresponding anatomical and clinical characteristics of SIANSA and SA systems.

SA system	Total number of areas in SA system	Number of areas anatomically correspondent with SIANSA lines	Number of areas clinically correspondent with SIANSA lines
Aggregated TCM SA	27	13	11
Aggregated Penetrating SA	24	22	20
Cluster SA	7	5	5
Qin’s Eight Scalp Needles	5	3	3
Cranial Base SA	1	1	0
Jiao’s SA	16	11	11
Chinese SA	19	12	12
Temporal Three-needle SA	3	1	0
Functional SA	17	11	5
Broca area SA	1	1	1
Pyramid Decussation projection SA	1	1	1
Cranial Sutures SA	6	2	2
Neuroimaging SA	10	7	7
YNSA	26	11	3
Fang’s SA	7	6	5
Zhu’s SA	19	13	12
Parietal Acupoint Therapy	7	5	5
Bagua SA	3	1	1

SA = scalp acupuncture; SIANSA = Standard International Acupuncture Nomenclature Scalp Acupuncture; TCM = Traditional Chinese Medicine; YNSA = Yamamoto New Scalp Acupuncture..

Historically and theoretically, Jiao’s SA and Chinese SA are the two systems that closely align with SIANSA, both anatomically and in their relationship with each other. However, despite the apparent similarity, when described verbally or with images, the real anatomical equivalence of these SA systems was not clear due to the different approaches used for locating the exact position of the scalp landmarks. Bone proportional cun (B-cun) is used as a measurement unit in SIANSA [10:p.11, 33:pp. 11-20,23], whereas Jiao’s SA and Chinese SA use the metric system and marking lines (anterior-posterior median and supraciliary-occipital lines and hairline) [1:pp. 47-59, 11:pp. 56-74, 38:pp. 8-18]. As a proportional value, B-cun depends on the size and shape of the cranium as well as the personal measurement skills of an acupuncturist. Dependance on these three factors makes B-cun a variable unit. In Jiao’s SA and Chinese SA, marking lines are constructed as imaginary lines based on the midpoint between the eyebrows, the upper border of the eyebrow, and occipital tuberosity. Understanding and perceiving these anatomical landmarks depends upon the practitioner’s skills and can vary, offsetting the accuracy. Hao and Hao [1:pp. 251-253], Wang [11:pp. 56-71], and Nie [10:pp. 25-28] assumed that the lines in SIANSA, Jiao’s SA, and Chinese SA are identical, although none of the authors elucidated how the bone proportional cun measurement method, metric system, and cranial anatomical landmarks were correlated.

Similar uncertainties surrounded the establishment of precise anatomical positions for other SA system areas on the scalp. Whether an SA system used TCM points on the head, metric system, or cranial anatomy, synthesis based on anatomical characteristics was unachievable. A comparison of SA areas based on verbal and pictorial descriptions revealed variable methods of locating anatomical landmarks in different systems, hindering their integration. The zones of somatotopic representation of the body on the scalp (Zhu’s SA [39:pp. 3-8], YNSA [6:pp. 69-86,99-108], Fang’s SA [52,53], and PAPT [45]) were unique to each system and did not have any commonalities that would enable synthesis.

2. Synthesis based on clinical characteristics

The discrepancies in anatomical characteristics were mirrored by the lack of consistent correspondence of clinical indications. Table 3 shows that anatomical match between SIANSA and other SA system areas does not necessarily imply a correlation in their clinical application. The SA systems, which were created based on neuroscience, tend to have identical indications for anatomically corresponding zones. SA systems based on the TCM theory and knowledge varied between each other and SIANSA in their clinical characteristics for anatomically matching areas. Their treatment application depended on the TCM theory applied (Meridian, Zhang-Fu, Yin-Yang, Qi-Blood, Five-elements, etc.) and the TCM school tradition. Bagua SA was applied to the treatment of all neuropsychological disorders.

C = Clinical indications Correspond; NC = Clinical indications do Not Correspond; PC = Clinical indications Partially Correspond; SIANSA = Standard International Acupuncture Nomenclature SA; TCMSA = Aggregated TCM SA points; PSA = Aggregated Penetrating SA points; QESN = Qin’s Eight Scalp Needles; CB SA = Cranial Base SA; ChSA = Chinese SA; TTNT = Temporal Three-needle Therapy; FSA = Functional SA; BA SA = Broca area; PDP SA = Pyramidal Decussation projection SA; CS SA = Cranial Sutures SA; NI SA = Neuroimaging SA; YNSA = Yamamoto New SA; PAPT = Parietal Acupoint Therapy..

&md=tbl&idx=3' data-target="#file-modal"">Table 3

Correspondence of clinical Indications between anatomically matching areas of SIANSA and SA systems.

SA system	SIANSA lines
	MS1	MS2	MS3	MS4	MS5	MS6	MS7	MS8	MS9	MS10	MS11	MS12	MS13	MS14
TCMSA	C		NC		C	C	C			C	C	NC		C
PSA	C	NC	NC	NC	C	C/NC	C	C	C	C	C	C		C
Cluster SA	C	C			PC	PC	PC			PC		C	C	C
QESN			PC		C		C				PC
CB SA														NC
Jiao’s SA		C	C	C	C	C	C	C	C	C	C		C	C
ChSA	C	C	C	C	C	C	C	C	C	PC	C		C	C
TTNT							NC
FSA	C	C	NC		C		PC		PC		NC	NC	NC
BA SA						C				C
PDP SA														C
CS SA					C	C	C				C
NI SA	C				C	C	C			C	C
YNSA	NC	NC	NC			C	NC	C			NC	C	C
Fang’s SA	C/NC	C/NC	C/NC	C/NC	C	C	C					C	C
Zhu’s SA	C		C	C	C			C			C	PC	PC
PAPT	C	C			C							C
Bagua SA								C

C = Clinical indications Correspond; NC = Clinical indications do Not Correspond; PC = Clinical indications Partially Correspond; SIANSA = Standard International Acupuncture Nomenclature SA; TCMSA = Aggregated TCM SA points; PSA = Aggregated Penetrating SA points; QESN = Qin’s Eight Scalp Needles; CB SA = Cranial Base SA; ChSA = Chinese SA; TTNT = Temporal Three-needle Therapy; FSA = Functional SA; BA SA = Broca area; PDP SA = Pyramidal Decussation projection SA; CS SA = Cranial Sutures SA; NI SA = Neuroimaging SA; YNSA = Yamamoto New SA; PAPT = Parietal Acupoint Therapy..

Although some of the areas of SA systems based on body somatotopic representation matched SIANSA lines anatomically, their clinical indications were SA system-specific and had a low degree of correspondence with SIANSA. Neuroimaging SA stands out from the rest of the SA systems because it is a functional approach that lacks unchanging anatomical characteristics. It integrates the knowledge of neurological connections between the scalp and underlying brain zones and their functions using special equipment to individually locate the areas of the scalp to be stimulated for each patient.

This ScR intended to identify the scope of SA systems available for English-speaking stakeholders, search for common features, including anatomical and clinical characteristics, systematize them, and perform framework synthesis, which would facilitate the standardization of SA. The results highlighted the heterogeneity of SA systems, which can be attributed to variations in theoretical bases, discrepancies in the methods for locating SA areas, and medical pluralism and multiplicity. Diverse viewpoints on the locations of anatomical features and clinical indications of SA systems have impeded the synthesis of an SA framework.

1. Heterogeneity of SA systems

This ScR confirmed the high variability of SA systems. SA legitimization and integration with Western healthcare systems is determined by SA’s ability to comply with biomedical epistemologies and evidence standards [54]. Reductionism is an inherent quality of Western biomedicine, as opposed to a systemic approach with context, space, and time as the principal factors [55]. Distinct anatomical features, strict diagnostic classification, selective treatment approach, and focus on efficacy and effectiveness are also crucial attributes of biomedicine [56,57].

The multiplicity of SA systems and their heterogeneity contradicts the reductionist nature of Western medicine. This review attempted to understand the commonalities among characteristics of modern SA and to synthesize a framework for SA systems to align SA more closely with biomedical perspectives. Three types of variables potentially contributing to SA heterogeneity were recognized in this review: theoretical grounds of SA, positioning of SA areas on the cranium, and medical pluralism and multiplicity.

2. Theoretical grounds

An analysis of 19 SA systems revealed a spectrum of theoretical rationales, transitioning from being rooted solely in Chinese medical theory and knowledge, through combinations of the TCM theory and biomedicine, to being exclusively founded on neuroscience (Fig. 3). This transformation followed the pattern of the historical development of SA, with newer SA models being more biomedicine-oriented. This mirrored the availability of information on SA systems in English; TCMSA literature is less likely to have full English texts, whereas texts on SA systems based on biomedical knowledge or TCM and biomedicine would usually have exhaustive information on the subject. This observation supports the perspective put forward by Birch and Tsutani [58], who related the state of English-language publications with the development of oriental medical traditions in the West.

A distinct subgroup of four SA systems based on somatotopic representation of the body on the scalp was also found. Each of these systems constituted a separate MS with unique anatomical characteristics and correlated to their clinical characteristics. MS SA systems are based on oriental philosophy and medical knowledge, with elements of the Western biomedical approach [7]. Their notable distinctions begin with theoretical foundations and extend into anatomical features and clinical applications. As an illustration, in this SA subgroup, the area between GV23 and GV24 could be associated with basal ganglia, head, face, lower/upper extremities, sacrum, coccyx, and brain stem. Such polymorphism in opinions on the distribution of the body pattern on the scalp hampers the wide comprehension of these SA systems and their clinical use. Furthermore, it complicates the understanding of their place within the whole phenomena of SA and makes standardization impossible, limiting future research in the field of SA.

The theoretical basis also determines the approach to diagnosis and treatment. Holistic TCM recognizes the mind, body, and environmental factors as interconnected parts of a whole system [59,60]. The application of this paradigm in clinical practice creates multiple specific variations in diagnostics and treatment protocols [61], which are beyond comparison and standardization due to their heterogeneity. The TCMSA points within Chinese medical theory are used as integral parts of 12 meridians, Yin/Yang, Zang-Fu organs, and other components of the system, and the knowledge and practical skills of the acupuncturist make the TCMSA protocol patient-tailored, with unique points for each case.

The SA systems that integrate TCM and biomedical concepts are structured systematically, with treatment areas clearly defined by their anatomical position and clinical indications. The presence of a distinct structure enables treatment protocols to be specific to the condition, making these systems easier to comprehend and use in practice. In this situation, the skills of the acupuncturist are less important; therefore, more practitioners can practice SA, and SA would be more accessible to a wider population. The coherent definition of anatomical and clinical characteristics of SA systems makes them amenable to systematization and repeated analysis, thus facilitating research on SA within the biomedical paradigm.

Notably, the treatment application of the theories underlying SA systems is patient-tailored and applies to both SA systems based on TCM and those based on neuroimaging. SA methods based on neuroscience utilize biomedical imaging technologies that require the use of special equipment, producing precise protocols for specific patients. The high costs of neuroimaging equipment, specialized skills of the medical staff, and individualized treatment protocols decrease the availability of neuroimaging-based SA to a wider population. Nevertheless, this SA approach may be the first step toward the generalization of bioscience-based SA and the development of widely applicable standard treatment protocols.

Despite deviation in the theoretical foundation from the original ideas of Chinese medicine to modern bioscience, TCM head acupuncture points remain a constant element used in 15 out of 19 SA systems for describing the position of the stimulation areas on the scalp.

3. Anatomical characteristics and measurements

A detailed examination of the anatomical characteristics of SA systems revealed a notable discrepancy in the methods employed across different SA systems for locating treatment areas. A combination of TCM head acupuncture points, anatomical features, and metric measurements was employed. The positioning of TCM head points was performed using the proportional B-cun method and cranial landmarks. However, the ultimate determining factor in this process is the acupuncture practitioner’s skill and judgment. The use of divergent methods for measurement and the lack of consensus on the location of landmarks on the cranium create inaccuracies in the positioning of SA treatment zones.

The inconsistencies in the correct localization of acupuncture points and areas is a challenge common to both acupuncture and SA, and this has been recognized and addressed by several authors. Godson and Wardle [62] emphasized the importance of the correct positioning of acupuncture points for safe and efficient treatment and valid and reliable research. Their systematic review exposed considerable discrepancies in acupoint localization among acupuncturists, influenced by their skills and the methods used to find acupuncture points, and concluded that a satisfactorily precise method for point location in acupuncture remains to be established.

Gao and Peng [63] used cadavers to investigate the motor and sensory areas of SA and found a mismatch between the textbook descriptions and the actual correspondence of the scalp and brain anatomy. Their findings suggested that the SA motor and sensory areas should be positioned 1 cm and 3 cm posterior to the midpoint of the head anterior-posterior midline on their upper ends and 1 cm and 2 cm posterior to the positions stated in the textbook at their lower ends, respectively. Recognizing the significance of accurate point location and aiming to overcome the variability caused by the impact of anatomical, proportional, morphological, and palpatory considerations, Kim and Kang [64] used a partially automated method to position standard acupuncture points on the head. To clarify the anatomical relationships between the SA areas and the underlying corresponding zone of the cortex, Shen et al. [65] researched the position of GV20 in relation to the central and precentral sulcus using 3D image technology. They found that it is located in the projection of the frontal lobe anterior to the precentral sulcus, and the distance between the GV20 and the precentral sulcus is greater in adults.

Stimulation of the precise area of the scalp is a fundamental principle of all SA systems. Inaccurate localization of the zone for stimulation may have serious consequences for the patient, as dysfunctions of the CNS are the main areas of SA application in practice. The multiple methods employed for measurement and the lack of consensus on anatomical characteristics within and between SA systems create a high potential for errors in the identification of treatment areas on the scalp, impeding the SA systematization and research. Despite the growing recognition of the lack of consensus on the positioning of acupuncture points and areas and its impediment to the development of acupuncture in the modern world, studies in this area remain isolated and inconsistent.

4. Medical pluralism and multiplicity

Medical pluralism describes the coexistence and availability of medical traditions and practices with distinct epistemological foundations and unique worldviews [54,66]. Biomedicine and non-Western Complementary and Alternative Medical (CAM) traditions can exist and interact within the same healthcare system or medical practice—every contemporary society has some degree of medical pluralism [54,66]. Mirroring the concept of medical pluralism, SA conjoins foundational theories and principles and other characteristics of biomedicine and Chinese medicine to various extents, producing variable SA systems. Uibu and Koppel [67] identified five categories describing the positioning of CAM health approaches in relation to biomedicine, and these categories align with the distribution of the foundational theoretical bases of SA systems (Fig. 3, Table 4).

CAM = Complementary and Alternative Medicine; SA = scalp acupuncture; TCM = Traditional Chinese Medicine..

&md=tbl&idx=4' data-target="#file-modal"">Table 4

Correlation of SA foundational principles with CAM/biomedicine relation within medical system.

	Five types of relationships between Biomedicine and CAM [67], and correlated five types of foundational theoretical principles of SA
CAM in relation to biomedicine [67]	Superiority of CAM, distrust towards biomedicine	Implicit superiority of CAM	Integrative medicine	CAM under the hegemony of biomedicine	Biomedicine as an exclusive dominant authority
SA foundational theoretical principles (Fig. 3)	TCM only	TCM and elements of biomedicine (neuroscience)	TCM combined with biomedicine (neuroscience, psychology)	Biomedicine (neuroscience) with use of anatomical TCM locations	Biomedicine (neuroscience, neuroimaging), some reference to TCM anatomical locations

CAM = Complementary and Alternative Medicine; SA = scalp acupuncture; TCM = Traditional Chinese Medicine..

The heterogeneity of SA systems is supported by the innate tendencies within biomedicine and Chinese medicine toward a lack of fixed patterns in practical implementation. Multiplicity in medicine is the result of the conjoined influence of the environment, practitioner, and dominant medical system when biomedicine and Chinese medicine inevitably interpenetrate and shape each other [68]. Diversity in response to local environmental factors is natural and provides conditions for a system’s survival and development; therefore medical systems and practices are naturally diverse despite standardization [68]. This also applies to Chinese medicine, which flexibly mirrors the cultural context and can be tailored according to the customs and beliefs of the community where it is practiced [69]. The plurality in Chinese medicine is its intrinsic and nonreducible quality [56]. It is supported by the subjectivity of the practitioner’s interpretation of the theory, evidence, and personal experience [68]. Hsu [70] highlighted that acupuncture schools often emerge in association with charismatic figures who provide their own interpretation of Chinese medical knowledge within or outside the biomedical field. The traditional complexity and diversity of oriental medical reasoning could be another factor contributing to the discrepancies in the localization of SA areas and the ongoing development of new SA methods [56,62].

5. Language

The extensive literature search yielded 33 SA systems; however, information on 14 SA systems was unavailable because the abstracts lacked detail and full-text publications in English were unavailable. Out of the 87 texts included for review, 47 were abstracts in English with full text in other languages. Birch and Tsutani [58] showed that the assimilation of literature from East Asian countries may reflect the status of acupuncture development in the West. Thus, the proportion of publications in English could indicate the present state of SA evolution and expansion. SA is a relatively recent concept and may still be in its early phase of development in English-speaking countries, which could explain the scarcity of English texts on the subject.

The distribution of English publications by year (Fig. 2) supports the theory proposed by Birch and Tsutani [58]. The earliest publications were English translations of the works of Dr. Jiao Sun Fa and WHO SIANSA, and the first English abstracts on TCMSA trials emerged only after 2000. Following the popularization of SA as a treatment approach, English publications increased sharply after 2010, and the literature on neuroscience-based SA systems is likely to be more recent. Overall the proportion of English publications by year may reflect the level of integration of SA with biomedicine and its incorporation into the dominant healthcare system [54].

6. Limitations

This ScR addressed the breadth of the publications on SA, aiming to detect the full range of existing SA systems. A wide range of data sources, study designs, and methodologies were included in the review. Critical appraisals of the included literature and assessments of the quality of evidence were not included because the focus was instead on providing a comprehensive summary. However, it is important to acknowledge that this limitation has restricted the formulation of recommendations for practice [26,28]. Additionally, the vast volume of publications screened could have introduced errors in the screening process. Furthermore, as an MSc project, a sole researcher performed searches, screening, and data extraction. However, the input of additional authors would have decreased the possibility of potential data loss.

Language is a common limitation for reviews on oriental medicine [71]. Limiting the inclusion criteria to publications with detailed descriptions in English may have resulted in the omission of data and prevented the inclusion of 14 SA systems. The linguistic barrier in this review seriously impacted the comprehensive understanding of the SA phenomena. Nevertheless, this ScR focused on information available for English-speaking stakeholders and contributed to a better understanding of the status of SA as a treatment modality in the West.

7. Implications for practice and research

Because the methodological quality of the evidence was not assessed in this review, practice recommendations were not developed here. However, the authors anticipate that the information collated for framework synthesis will be of interest to practitioners, researchers, and other SA stakeholders. Notably, the absence of a consensus on the anatomical characteristics of SA increases the potential for treatment errors and interferes with the standardization of SA. Therefore, discussion and consensus on the anatomical characteristics of SA among stakeholders are of foremost importance for the effectiveness and safety of SA and for supporting the standardization of SA, which is essential for further research in this area. Building an SA framework based on the theoretical foundations of SA systems could be another step towards a more comprehensive understanding of the SA phenomena. Furthermore, incorporating the non-English literature on SA systems in future reviews would facilitate the comprehensive generalization of the existing knowledge on SA.

SA has the potential for use in treating neurological conditions. However, the high variability of SA systems limits evidence synthesis and secondary analysis and, consequently, evidence-based health policies. This review identified 33 SA systems; however, information in English was available for 19 of the identified SA systems. The heterogeneity of SA systems results from the variability in the foundational theoretical bases, inconsistencies in the anatomical location of treatment points and areas on the scalp, medical pluralism, and innate multiplicity in medicine. Further research in this area should focus on identifying methods of measurement for the precise positioning of acupuncture points and areas on the scalp. The implementation of framework synthesis based on the theoretical foundations of SA systems could contribute to a deeper understanding of the SA phenomena.

We gratefully acknowledge help and advice of Dr Morag Heirs (Northern College of Acupuncture) and Dr Cath Mortimer (Northern College of Acupuncture). Special thanks to Frank Böhm for his kind help with proofreading. Invaluable insight of Kelvin Chan into the East-Asian names convention is very appreciated.

Supplementary data to this article can be found online at https://doi.org/10.51507/j.jams.2023.16.5.159

The publishing of this study was supported by the Northern College of Acupuncture, York, UK.

Conceptualization: Svetlana Wise; Formal analysis: Svetlana Wise; Funding acquisition: Svetlana Wise; Investigation: Svetlana Wise; Methodology: Svetlana Wise; Project administration: Svetlana Wise; Supervision: Ava Lorenc; Visualization: Svetlana Wise; Writing - original draft: Svetlana Wise; Writing - review & editing: Ava Lorenc.

The authors declare no conflict of interest.