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Original Articles: Gastroenterology

Electrodermal Activity of Auricular Acupoints in Pediatric Patients With Functional Abdominal Pain Disorders

Borlack, Rachel E.∗,†; Shan, Sophie; Zong, Amanda M.; Khlevner, Julie§; Garbers, Samantha||; Gold, Melanie A.

Author Information
Journal of Pediatric Gastroenterology and Nutrition: August 2021 - Volume 73 - Issue 2 - p 184-191
doi: 10.1097/MPG.0000000000003137

Abstract

An infographic is available for this article at: https://links.lww.com/MPG/C322.

What Is Known/What Is New

What Is Known

  • Functional abdominal pain disorders (FAPD) are common in pediatric patients and are often debilitating with limited pharmacologic treatment options.
  • Auriculotherapy is used to manage procedural and acute and chronic pain in pediatric and adult patients.
  • Electrodermal measurements determine active acupoints associated with symptoms or conditions that can be used for treatment.

What Is New

  • Electrodermal auricular measurements identify auricular acupoints that are active in pediatric FAPD patients.
  • Some of the auricular acupoints used to treat generalized pain and/or gastrointestinal symptoms are not active in children with FAPD.
  • We propose a new treatment protocol to help manage symptoms in pediatric patients with FAPD.
  • Patients and families of children with FAPD are interested in auricular acupressure as a treatment option and are less interested in treatment using needles.

Functional abdominal pain disorders (FAPD) affect approximately 13.5% of children (1–3). Children with FAPD report low quality of life scores and frequently have psychiatric comorbidities (4,5). The pathophysiology is complex and not entirely understood, involving the brain-gut axis, genetic predisposition, psychosocial events, and autonomic dysfunction contributing to symptom development (6–8). There is limited evidence for pharmacologic treatment in pediatrics, often involving polypharmacy, leading many patients to suffer from symptoms into adulthood (9–12). Lack of effective treatment options and poor clinical response has led to increased interest in integrative medicine, including auriculotherapy (13).

Auriculotherapy involves stimulating auricular acupoints (AAs) to treat symptoms or disease with evidence demonstrating safety and efficacy for pain relief in children (14). Similar to the homunculus of the brain, there are regions of the ear thought to be associated with different anatomic structures, body systems, or specific illnesses (15,16). Newer research investigating the pathophysiology found neurovascular complexes within the dermis of AAs, which via stimulation can affect brain signaling as suggested by functional brain magnetic resonance imaging (fMRI). Additionally, cranial nerve branches in the ear can communicate centrally to impact the autonomic nervous system. (17–21)

When assessing AAs for treatment, providers can use a handheld point-finder device to measure transdermal current. Active acupoints have lower resistance resulting in higher current compared to inactive acupoints or non-acupoint areas (16,18). Oleson et al validated the accuracy of a point-finder examination to locate the anatomic source of pain (22). Subsequent studies across several conditions were unable to consistently correlate electrodermal activity with a condition, such as dysmenorrhea, possibly related to variability in study design (23–27).

This pilot study aimed to measure the electrodermal activity of AAs in female pediatric patients with FAPD compared to age-matched healthy controls (HC) and assess awareness and interest in auricular acupressure as a treatment option.

METHODS

Study Design and Participants

Participants were recruited from January to September 2019. Participants were either diagnosed with FAPD or were healthy. Only females were recruited to minimize confounders due to evidence showing that irritable bowel syndrome (IBS) management can be impacted by sex (28,29). The criteria for participation in both groups included: female, age 7–21 years, and English speaking. For the FAPD group, participants required a diagnosis of functional dyspepsia (FD), IBS, or functional abdominal pain-not otherwise specified (FAPD-NOS) based on Rome IV criteria (6,30,31). Because of increased psychiatric comorbidities in FAPD, participants with reported anxiety or depression were included in FAPD, but excluded from HC. Participants were excluded if they had: recent injuries, underlying medical conditions (except for mild asthma), current pregnancy, ear infection, ear malformation/abnormality, ear piercings that interfered with assessment, any co-morbidities (except for the above-mentioned), or a pacemaker.

Participant recruitment was from four pediatric gastroenterology clinics, two pediatric clinics, flyers, online advertisements on an academic research recruitment website, and social media platforms. All participants underwent an initial screening to determine eligibility. If deemed eligible, informed consent was obtained and participants attended a single 1-hour research visit to complete a pre-assessment survey, the auricular assessment, and a post-assessment survey. The study was approved by the institutional review board.

Intervention and Control

Twenty AAs per ear on both ears were evaluated. International agreement on nomenclature and function of AAs is continuously evolving. For this study, anatomic maps were based on the World Federation of Acupuncture-Moxibustion Societies (WFAS) and Dr Terry Oleson's revised World Health Organization (WHO) system and published nomenclature, with the noted origin of terminology if differs between European and Traditional Chinese Medicine (TCM) (16,32). It is important to note that while the AAs are often named for a body part or function, this is based on historical experience rather than evidence. There were two groups of AAs included: the gastrointestinal-related AAs (GIAA), which included AAs recommended for or hypothesized to be associated with the gastrointestinal system, pain, and/or anxiety disorders (16,33) and control AAs (CAA), hypothesized not to be associated with these conditions. The AAs and their proposed functions can be found in Table 1.

TABLE 1 - Anatomic location and attributed function of each auricular acupoint (AA) used in auricular assessment (16,22,32)
Auricular acupoint Origin Zone (WFAS/WHO) Reported function
GIAA
 Abdomen TCM/EU AH9/AH11 Diminishes abdominal pain, lumbar pain, and hernias
 Cingulate gyrus EU CO18/IT1 Part of limbic system, can treat chronic pain and improve emotional suffering and memory
 Constipation TCM TF3/TF3 Alleviates constipation and indigestion
 Esophagus TCM/EU CO2/IC7 Represents the esophagus, can treat acid reflux, indigestion, issues with swallowing, and sore throats
 Large intestine TCM/EU CO7/SC3+4 Represents the large intestine, alleviates diarrhea, constipation, colitis, hemorrhoids, or enteritis
 Master cerebral TCM/EU LO4/LO1 Represents prefrontal and part of cerebral cortex. Decreases anxiety, fear, and psychosomatic disorders, can help with sleep and memory
 Point zero prime 2 TCM/EU HX1/CR2 Center of auricle, helps with whole body homeostasis, energy, brain, and hormone balance
 Psycho-somatic EU HX4+5/HX4+5 Helps with psychological disorders, facilitates remembering repressed memories and experiences
 San Jiao TCM CO15/IC1 Treats diseases of internal organs and endocrine glands, including circulatory (regulates water circulation and fluid distribution) and respiratory systems and thermoregulation. Alleviates indigestion, anemia, hepatitis, constipation, and edema
 Small intestine/omega 1 TCM/EU CO6/SC2 Represents the small intestine, alleviates indigestion, bloating, diarrhea, and malnutrition
 Stomach TCM/EU CO4/CR1 Represents the stomach, regulates appetite, and alleviates diarrhea, indigestion, nausea, gastritis. Also alleviates headaches and stress
 Thalamus TCM/EU AT4/CW2+IC4 Functions related to brain diencephalon, relay of sensory information and regulation of autonomic system and endocrine glands. Regulates over excitation of neurons, helps with chronic pain and anxiety
 Tranquilizer TCM/EU TG2/TG2 Helps with relaxation and/or sedation, anxiety, stress, and hypertension
CAA
 Ankle TCM AH1+2/AH17 Diminishes ankle pain or injury
 Bladder TCM/EU CO9/SC5 Infections or conditions affiliated with bladder and urinary tract
 External nose TCM TG1/TG3 Helps with damage to external nose, such as fracture or sunburn
 Face TCM/EU LO6/LO5 Diminishes facial spasms, tics, and acne
 Finger TCM/EU Diminishes pain, swelling, and arthritis of the finger
 Omega 2 EU HX6/HX6 Alleviates somatic stress, pain and inflammation relief for the limbs
 Thoracic spine TCM AH11/AH9 Alleviates back and shoulder pain
Anatomic zone locations are presented according to the World Federation of Acupuncture-Moxibustion Societies (WFAS) and Dr Terry Oleson's revised World Health Organization (WHO) system.CAA = control AA hypothesized not to be associated with FAPD; EU = European; GIAA = AA hypothesized to be associated with functional abdominal pain disorders; TCM = Traditional Chinese Medicine.

Study Visit

All surveys were completed by participants, with the aid of a guardian if under 18 years of age, on an encrypted tablet. The pre-assessment survey included demographics, current abdominal pain score using a visual analogue pain scale, Bristol stool scale (34), anxiety and depression screening, interest in acutherapy, and for the FAPD group, the Rome IV questionnaire (30). Anxiety and depression scores were assessed in all participants on a Likert scale from 1 to 5 with 1 equal to never have anxiety/depression and 5 equal to always have anxiety/depression.

The principal investigator is a pediatrician board certified in medical acupuncture, who trained the lead investigator (LI) in auriculotherapy with over 30 hours of hands-on training. Each auricular assessment was conducted by a research assistant (RA) under the supervision of the LI to ensure consistency. RAs had no prior expertise in auriculotherapy and were trained to perform the assessment using the point-finder device requiring more than 10 hours of training. A single point-finder device (acupuncture pen manufactured by iVOLCONN, Shenzen, China) was used for all participants. It uses asymmetric biphasic square wave and contains a monitor that shows electrical current in μA. A higher current indicates lower resistance and therefore a more active AA. The device was used with a 2 mm spring-loaded tip and direct skin contact. The spring tip allows for some variation in the pressure applied by RAs without affecting the electrodermal measurement. The ears were first cleaned with alcohol. Participants were randomized to left or right ear first using a computer randomizer. The device was zeroed to each participant per ear by adjusting the sensitivity to give a current measurement between 50 and 55 μA for the AA Shen Men. Shen Men is an AA associated with pain and anxiety, typically active in everyone. Zeroing the device accounts for intrinsic current differences in participants and RAs. Because the device is zeroed to 50–55 μA on an active AA, Shen Men, any AA ≥50 μA was defined as active for median analysis (16). Once zeroed, the RA proceeded to the 20 AAs in a set order. The RA identified each AA and the participant would select tenderness level using a visual pain scale from 1 to 6 (1 being no pain and 6 being the most pain), then the RA would determine the current measurement. The device takes 5–60 seconds to adjust to a new AA and continues to fluctuate by approximately 0–3 μA once achieving a steady state, so the RA would choose the most stable current.

After completion of bilateral auricular assessments, each participant completed a 5-minute post-assessment survey, including feedback on the assessment and future interest in auriculotherapy. Participants were given a US$15 prepaid gift card at the completion of the study visit.

Blinding

The auricular assessments were double-blinded by numbering all AAs and only referring to them by the assigned number during the study. RAs and participants were unaware of the function or name of all AAs, except Shen Men. RAs completed a questionnaire at study completion to assess blinding success.

Statistical Analysis

T-tests were used to evaluate baseline characteristics. Median values for each AA were analyzed by group and compared between groups using chi-square analysis. Due to possible variance in technique and participants despite the previously outlined precautions, the meter value of each AA was ranked per participant to account for the relative, rather than absolute, current measurement and ranks were averaged for each AA across participants to generate the average relative rank. Participants were considered outliers and removed from median and average ranking analysis if their overall median was >1.5 interquartile range from the group median. Meter value correlation with participant-reported tenderness was evaluated using Pearson's correlation. Wilcoxon rank-sum test was performed to evaluate the pre-test hypothesized AA function between GIAA and CAA.

RESULTS

After screening 139 potential participants, 46 females were enrolled, 22 FAPD and 24 HC, age 8–21 years. The most common reason for not enrolling in the study was the inability to schedule an in-person visit after initial eligibility screening (Fig. 1, Supplemental Digital Content, https://links.lww.com/MPG/C321). Participants were recruited from six clinical sites across New York, NY, Long Island, NY, and Stamford, CT, in addition to online recruitment. Outlier calculations revealed one outlier per group, which were eliminated from median and average relative rank analysis. All participants successfully completed the auricular assessment and no serious adverse events were reported, although three participants reported high levels (>5/6 on the pain scale) of auricular tenderness during the assessment. Participant baseline demographics are depicted in Table 1. The average age of FAPD and HC participants was 15.8 and 15.4 years (P = 0.96), respectively. There was no significant difference in Bristol stool scale between the groups, but there was a significantly higher anxiety score (P = 0.008) and abdominal pain score (P < 0.001) on the day of assessment for the FAPD compared with HC (Table 2).

TABLE 2 - Summary of participant demographics, baseline characteristics, and pre- and post-assessment acutherapy experience and interest
Variable All participants (n = 46) FAPD (n = 22) HC (n = 24) P-value
Mean age (y) 15.72 15.68 15.75 0.956
Post-menarche, n (%) 35 (76.1%) 18 (81.8%) 17 (70.8%) 0.670
Hispanic, n (%) 13 (28.3%) 4 (18.2%) 9 (37.5%) 0.218
White, n (%) 21 (45.7%) 13 (59.1%) 8 (33.3%) 0.197
Parental education level (bachelor's degree or higher) 28 (60.9%) 13 (59.1%) 15 (62.5%) 0.882
Anxiety score 2.87 3.27 2.50 0.008
Depression score 2.17 2.36 2 0.160
Bristol Stool Test 3.37 3.47 3.27 0.588
Abdominal pain on day of assessment 1.69 2.38 1.05 <0.001
Pre-assessment, n (%):
Previous knowledge of acutherapy 20 (90.9%)
Auriculotherapy 3 (13.6%)
Acupuncture 20 (90.9%)
Acupressure 17 (77.3%)
Previous use of acutherapy 4 (18.2%)
Auriculotherapy 0 (0%)
Acupuncture 3 (13.6%)
Acupressure 1 (4.5%)
Interest in acutherapy treatment 16 (72.7%)
Auriculotherapy 10 (45.5%)
Acupuncture 10 (45.5%)
Acupressure 16 (72.7%)
Post-assessment, n (%)§
Interest in treatment with acupressure beads 19 (86.4%)
Interest in treatment with needles 7 (31.8%)
Willing to travel to clinic for treatment 15 (68.2%)
FAPD = functional abdominal pain disorder; HC = healthy controls.
Depression and anxiety were scored on self-reported scale from 1 to 5, where 1 is never having anxiety/depression and 5 is always having anxiety/depression.
Two participants from each group excluded because answered unsure.
Abdominal pain on day of assessment was evaluated using the visual pain scale from 1 to 6 where 1 is no pain and 6 is the most pain.
§Includes responses of definitely or probably yes.

In the pre-assessment survey, 90.9% of FAPD reported awareness of acupuncture, but only 13.6% knew about auriculotherapy (Table 1). Even though 73% of FAPD participants expressed interest in receiving any type of acutherapy, only 18% had previously received acutherapy. In the post-assessment survey, participants were shown a photo of an ear with acupressure gold adhesive beads. When asked if they would like to receive symptom treatment with these beads, 70.8% of FAPD responded definitely or probably yes, respectively, and when asked if they would travel to the clinic just to receive this treatment, 68.2% of FAPD responded definitely or probably yes; however, the percentage of interested FAPD participants declined to 31.8% if needles were used instead of adhesive beads (Table 1).

Table 3 shows the AA median values by group. Chi-square analysis found no significant difference for any AA between groups. Among the 12 AAs that were active in the FAPD, all but the external nose were GIAA. Only 6 of the 12 AAs that were active in the FAPD group were also active in the HC. Pertinent inactive GIAAs in the FAPD group include abdomen, constipation, large intestine, and esophagus. All CAA, except the external nose, were inactive in both groups. Wilcoxon rank-sum comparing GIAA and CAA found 84.6% of GIAA were significantly more active than CAA including external nose in CAA and 88.5% were significantly more active when the external nose was excluded from CAA (Table 1, Supplemental Digital Content, https://links.lww.com/MPG/C320).

T3
TABLE 3:
Device meter values by overall median and average relative rank for each auricular acupoint (AA) on bilateral ears

Average relative rank per AA can be found in Table 3. Similar to the median, the top 5 ranked AAs per ear for the FAPD group were all GIAA, except the external nose. Among those top 5 AAs per ear, five of five and three of five were active for the right and left ears, respectively. When analyzing the lowest five points by average rank, all AAs for both ears were inactive.

The top-ranked active AAs in FAPD were combined with Shen Men to create a treatment protocol of six points per ear (Fig. 1A). In addition, the lowest-ranked inactive AAs in FAPD were combined to make a placebo protocol with six points per ear (Fig. 1B). There was a significant difference in AA activity between treatment and placebo control protocols (P < 0.01). When comparing the right and left ears for both treatment and placebo protocol, there was no significant difference in AA activity (P = 0.83 and 0.87).

F1
FIGURE 1:
(A) Proposed auriculotherapy treatment protocol for functional abdominal pain disorders. (B) Proposed placebo control protocol (• indicates in a groove or ridge, ○ indicates on raised part of the ear, ▪ indicates AA hidden behind auricular fold).

Pearson's correlation analysis showed that tenderness on examination did not significantly correlate with current measurement across all AAs in both groups.

All 12 RAs completed a survey after the study was complete assessing knowledge of AA function. RAs achieved less than 50% agreement for 16 of 20 AAs. Among the four AAs that achieved 50% agreement, the RAs only correctly matched three AAs with the pre-test hypothesized function, demonstrating effective blinding of the RAs.

DISCUSSION

We performed a pilot double-blind prospective study with pediatric female participants with and without FAPD to evaluate electrodermal auricular activity. This study is the first to assess electrodermal auricular activity in a pediatric population and FAPD. Recent literature has investigated the pathophysiology behind auriculotherapy beyond TCM experience. Stimulation of AAs shows increased signaling in specific areas of the brain on fMRI (17,19). Another proposed mode of action is through cranial nerves V, VII, IX, and X, which innervate the ear and communicate with the hypothalamus, amygdala, and spinal cord, impacting the autonomic nervous system (20,21). The auricular concha is innervated by the vagus nerve and contains many AAs historically associated with internal organs, linking the cranial nerve theory and TCM (35). Based on auricular cranial nerve pathways, electrical stimulation devices were developed and proved efficacious in pediatric FAPD, demonstrating the possibility of auricular stimulation to manage FAPD (36).

Among studies investigating auricular electrodermal measurements, there is variability in successfully correlating a condition and AA activity, with some studies unable to find any correlation (24). Our study shared methodology to others that were successful in correlating AA activity with specific conditions (22,25–27). Colbert et al created a scoring system with recommendations for electrodermal activity studies (37). Our study design complied with many of the recommendations. Blinding was noted to be frequently limited or flawed in previous studies. Our double-blinding method is novel and proved to be effective. Because we used a commercial device, our study was limited in the categories of the electrode system and instrument/electrical parameters.

Auricular acutherapy protocols allow for the wide dissemination of acutherapy. Current protocols are typically opinion-based, but have proven effective in pediatric pain management (38–40). There are many expert proposed AAs to manage FAPD, requiring an experienced acutherapist for optimal treatment (16,33,41). One study applied, auricular acupressure beads to adults with IBS using AAs chosen by experts (large intestine, Shen men, lung, and endocrine) and found significant improvement without adverse effects, demonstrating the potential of auricular acupressure in FAPD, including ease of applicability; however, given AAs were selected by opinion for adults, it is possible alternative AAs would be more efficacious in a pediatric population.

The top active AAs were combined with Shen Men to create the first proposed protocol for FAPD in pediatrics. This concise protocol, while not yet validated, allows providers, patients, and/or caregivers to easily apply it using acupressure or inexpensive adhesive acupressure beads compared to a current auricular treatment device, which is expensive and requires placement by a trained provider (36). Because auricular acupressure has been shown to be safe (41,42), our protocol can be used immediately with the potential benefit far outweighing risk, while awaiting validation data from randomized controlled trials.

In our proposed treatment protocol, all AAs, except the external nose, were hypothesized to be active in FAPD. External nose was consistently active in FAPD and inactive in HC, implying clinical significance. One explanation is adjacent to the TCM AA for the external nose is the European AA point zero prime 1, which is reported to balance dysfunction throughout the body (16). Pertinent negative AAs from this study include the abdomen, constipation, large intestine, and esophagus, demonstrating the complexity of FAPD and the need for evidence-based treatment protocols (7). Our proposed treatment protocol was significantly more active than the placebo protocol in FAPD. This implies that for future research, the difference in protocols should prove sufficient to evaluate placebo effects in FAPD (43). Auriculotherapy research frequently uses inactive AAs as a placebo control allowing sufficient blinding (44).

Acupoint tenderness is often used to determine active acupoints and guide treatment. Previous studies demonstrated variability in the accuracy of tenderness compared to electrodermal measurements (22,27,45). In our study, AA tenderness did not correlate with electrodermal measurements. This could be explained by the large number of points assessed, making it more challenging for participants to differentiate sensation at each AA. Additionally, our population is younger than previous studies, which may impact perceived tenderness or reliability of pain scores.

Pediatric patients with FAPD frequently report using integrative medicine (10,13,46). In our study, 80% of participants heard of acutherapy, but only 15% reported previous acutherapy treatment despite 54% reported interest in usage, demonstrating a gap in care. During assessments, participants learned about auricular acupressure and experienced the auricular examination, which may explain the increased interest in auriculotherapy post-assessment. In addition to 86.4% reporting interest in adhesive acupressure beads, 40.9% of FAPD group responded “definitely yes” to coming to the clinic solely for auriculotherapy. Patient interest in the treatment itself can be of great value. Kaptchuk et al demonstrated that adults receiving placebo acupuncture reported significant improvement in IBS symptoms when combined with improved patient-provider relationship (47). By providing this service, providers can enhance their patient relationship and improve clinical outcomes.

There are several limitations to this study. This is a pilot study with a small sample size, limiting statistical conclusions and analysis, including subgroup analysis by age, menstrual status, or Rome IV diagnosis. Only female participants were included, reducing the generalizability of the results. Due to the paucity of data in auriculotherapy, including baseline activity in healthy children, the AAs included were based primarily on published experience. AAs not included could be equally or more active than those investigated. While a single device was used throughout the study, it is a commercial device without precision monitoring or validation. Overall, despite significantly higher abdominal pain scores in FAPD compared to HC, the mean score on the day of the assessment was low. The results may have differed if assessments were performed during periods of increased symptoms. Also, each assessment was a single session without longitudinal data, which could help correlate with evolving symptoms. The anxiety involved in participating in a research study may have altered data, specifically for emotion-related points. RAs did not have previous training in acutherapy, possibly affecting the quality of the examination, however, this allowed for blinding and provided consistency.

In conclusion, we demonstrate the need for disease-specific auriculotherapy and propose an auricular acupressure treatment protocol based on electrodermal measurements to manage FAPD-related symptoms. Additionally, we illustrated a large interest in acutherapy and its implementation as a treatment option. Further studies are needed with a larger sample size to confirm the active AA findings, evaluate longitudinal electrodermal findings, differentiate by Rome IV diagnosis, and validate the efficacy of this treatment protocol.

Acknowledgments

Grete King created images of auricles used for Figure 1A and B.

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Keywords:

auriculotherapy; electrodermal activity; functional abdominal pain disorders

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