Analysis of the Analgesic Mechanism of TENS-WAA During Non-anesthetized Colonoscopy Using EEG-fNIRS System

Analysis of the Analgesic Mechanism of Transcutaneous Electrical Nerve Stimulation Based on Wrist-ankle Acupuncture Theory During Non-anesthetized Colonoscopy Using Electroencephalogram-Functional Infrared Spectroscopy System

This study is a single-center, randomized controlled trial aiming to evaluate the analgesic mechanism of Transcutaneous Electrical Nerve Stimulation based on Wrist-Ankle Acupuncture (TENS-WAA) during unsedated colonoscopy using EEG-fNIRS technology to assess neural activity in brain regions associated with pain perception. Sixty patients aged 18-75 years, with stable cardiopulmonary function and a baseline visual analog scale (VAS) pain score <3, will be enrolled and randomly allocated into the intervention and control groups. The intervention group will receive TENS stimulation based on the Wrist-Ankle Acupuncture theory 10 minutes before the colonoscopy, with a frequency of 2 Hz and adjustable current intensity ranging from 1 to 9 mA. The control group will receive minimal-intensity sham stimulation under identical conditions. All participants will wear EEG-fNIRS devices to monitor neural activity in key pain-related brain areas, including the prefrontal cortex, anterior cingulate cortex, motor cortex, and parietal cortex. Primary outcomes include EEG-fNIRS data, while secondary outcomes are VAS scores at the four colonic bends, colonoscopy duration, and the correlation between EEG-fNIRS signals and pain perception. Statistical analyses will include multivariable linear regression, generalized estimating equations, and mixed-effects models to investigate the analgesic effects and neural mechanisms of TENS-WAA. This study seeks to provide innovative pain management strategies for patients undergoing unsedated colonoscopy and further explore the neuroregulatory potential of TENS-WAA technology.

Study Overview

• Status: Recruiting
• Conditions: Pain; Colonoscopy
• Intervention / Treatment: Device: Using an electrical stimulation device to relieve pain during colonoscopy

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Xiaonan Huang, master; Phone Number: 86+15700719913; Email: 1301090492@qq.com

Study Locations

• China
  • Shanghai
    • Shanghai, Shanghai, China, 200433
      • Recruiting
      • The First Affiliated Hospital of Naval Medical University
      • Contact: Xiaonan Huang, master; Phone Number: 13912830811; Email: 1301090492@qq.com
      • Sub-Investigator: xiaonan Huang, Master
      • Principal Investigator: Fanfu Fang, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

1. Inclusion Criteria:

   • Patients undergoing unsedated colonoscopy are eligible for inclusion in this study.
   • Aged 18 to 75 years.
   • Meeting the requirements for colonoscopy, with good cardiopulmonary function and stable vital signs.
   • A pre-procedural Visual Analog Scale (VAS) pain score of less than 3.

2. Exclusion Criteria:

   • Participants with speech or cognitive impairments.
   • Those with acute anal or rectal stenosis, acute perianal or rectal infections, acute diverticulitis, or active inflammatory bowel disease.
   • Women who are menstruating, pregnant, or breastfeeding.
   • Patients with active tuberculosis, hemophilia, or advanced malignant tumors.
   • Individuals with sensory disturbances, implanted pacemakers or defibrillators, or ankle skin ulcers.
   • Those who have used sedatives or analgesics either long-term or within the past 24 hours.
   • Individuals with any condition that interferes with EEG-fNIRS signal acquisition, such as cranial abnormalities, implanted metal or electronic devices, epilepsy, or neurological disorders.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Electrical stimulation group; According to the WAA theory, the selected Lower Zone 1 (LZ1) and Lower Zone 2 (LZ2) are defined as follows: LZ1 is located between the medial Achilles tendon and the medial malleolus, while LZ2 is positioned at the central inner edge of the ankle joint, near the posterior border of the tibia. Two electrode pads will be placed on each LZ1 and LZ2 of both legs, totaling eight electrode pads. The TENS-WAA device will be set to a frequency of 2 Hz, a pulse width of 500 μs, and a continuous waveform. Participants in the stimulation group will receive electrical currents at their maximum tolerable intensity below the pain threshold.	Device: Using an electrical stimulation device to relieve pain during colonoscopy; In the electrical stimulation group, the device's current intensity will be adjusted to the maximum tolerance below the participant's pain threshold, while in the control group, the current intensity will be set to the minimum.
Placebo Comparator: control group; Participants in the control group will have the electrodes placed in the same positions as those in the stimulation group, with identical electrical stimulation frequency and pulse width settings. However, the current intensity will be set to the minimum level.	Device: Using an electrical stimulation device to relieve pain during colonoscopy; In the electrical stimulation group, the device's current intensity will be adjusted to the maximum tolerance below the participant's pain threshold, while in the control group, the current intensity will be set to the minimum.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
NeuroActivity Correlation Index	The NeuroActivity Correlation Index is a metric calculated using machine learning models to quantify the correlation between EEG and fNIRS data. Data preprocessing involves selecting appropriate frequency bands of EEG Power Spectral Density and corresponding brain regions' ΔHbO2 and ΔHb changes, with normalization of the data. Feature engineering involves extracting statistical and temporal window features, possibly using dimensionality reduction techniques such as Principal Component Analysis to enhance model efficiency. The model training phase utilizes regression models such as linear regression or support vector machine regression, or methods like Canonical Correlation Analysis to discover correlations between EEG and fNIRS data, optimizing model parameters through cross-validation. The correlation index is calculated based on model outcomes, typically expressed as a percentage, reflecting the statistical correlation strength between the datasets.	during procedure

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain VAS score	VAS is used to assess pain. It is widely used in clinical practice in China. The basic method is to use a 10-cm long floating ruler with 10 scale marks on one side, with 0 and 10 marks at the two ends. 0 means no pain, and 10 means the most severe pain that is unbearable.	during procedure (When the endoscope passes through the hepatic flexure, splenic area and rectosigmoid junction)
Colonoscopy time		during procedure (The total time to reach the three bends and to the ileocecal valve and for the entire examination was recorded)
Correlation between EEG-fNIRS and pain VAS scores	The neurophysiological and hemodynamic indicators were correlated with pain scores using AI machine learning methods.	up to 24 weeks

Collaborators and Investigators

• Sponsor: First Affiliated Hospital of the Chinese People's Liberation Army Naval Medical University
• Collaborators: Shanghai Shuli Intelligent Technology Co., Ltd

Study record dates

Study Major Dates

• Study Start (Actual): February 18, 2025
• Primary Completion (Estimated): August 30, 2025
• Study Completion (Estimated): February 15, 2026

Study Registration Dates

• First Submitted: January 16, 2025
• First Submitted That Met QC Criteria: February 6, 2025
• First Posted (Actual): February 7, 2025

Study Record Updates

• Last Update Posted (Actual): August 8, 2025
• Last Update Submitted That Met QC Criteria: August 5, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Peripheral Nervous System Agents; Sensory System Agents; Analgesics, Non-Narcotic; Analgesics; Antipyretics; Acetaminophen
• Other Study ID Numbers: CHEC2025-006

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

De-identified individual participant data (IPD) that will be shared include:

Demographic information (age, sex, colonoscopy history)

Group allocation (TENS-WAA or sham stimulation)

Pain Visual Analogue Scale (VAS) scores at key time points

EEG and fNIRS raw and pre-processed data collected before, during, and after colonoscopy

Procedure duration and event timepoints (e.g., reaching hepatic flexure, splenic flexure, ileocecal valve)

Relevant clinical outcomes (e.g., adverse events, procedure completion status) The data will be available from the corresponding author upon reasonable request, following publication of the main results and with a signed data access agreement. No data that could directly identify individual participants will be shared.

• IPD Sharing Time Frame: The de-identified individual participant data (IPD) and supporting documents (such as data dictionaries and analysis code) will be available beginning 6 months after publication of the primary results article. Data will remain available for at least 5 years after publication, or longer if required by journal or institutional policy. Requests submitted after this period may be considered at the discretion of the corresponding author and study team.
• IPD Sharing Access Criteria: Researchers from academic institutions, hospitals, or other recognized research organizations may access the de-identified individual participant data (IPD) and supporting documents (such as data dictionary and analysis code) for legitimate scientific research purposes by sending an email request to the corresponding author. The request should briefly describe the intended research use. All requests will be reviewed by the study team to ensure ethical compliance. Data sharing will require a signed data access agreement. Only de-identified data will be shared; no information that could directly identify participants will be provided.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No