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NCT Number: NCT06813703

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

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Key information

Conditions

Colonoscopy Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

The First Affiliated Hospital of Naval Medical University

Shanghai, Shanghai Municipality, 200433, China

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

  • 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.
  • 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.

Treatment and study plan

Using an electrical stimulation device to relieve pain during colonoscopy

Device

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.

Primary outcomes

  1. EEG-fNIRS Neurovascular Coupling Peak β Coefficient

    Time frame: During colonoscopy, at predefined procedural stages including anal intubation, splenic flexure, hepatic flexure, and cecal intubation, within the prespecified analysis window for each stage.

    Neurovascular coupling is quantified from synchronized electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) recordings. EEG activity is decomposed into predefined delta, theta, alpha, and beta frequency bands, and band-specific power envelopes are coupled with fNIRS-derived oxygenated haemoglobin (HbO) signals within predefined cortical regions of interest. A 10-second lag is applied to account for the delayed haemodynamic response following neural activity. Coupling is estimated using a general linear model. The peak β coefficient within the predefined analysis window is used to quantify maximum EEG-fNIRS neurovascular coupling strength. Values are calculated separately for the predefined frequency bands and cortical regions of interest and compared between the distal transcutaneous electrical nerve stimulation and sham stimulation groups.

  2. EEG-fNIRS Neurovascular Coupling β Area Under the Curve

    Time frame: During colonoscopy, at predefined procedural stages including anal intubation, splenic flexure, hepatic flexure, and cecal intubation, within the prespecified analysis window for each stage.

    Neurovascular coupling is quantified from synchronized electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) recordings. EEG activity is decomposed into predefined delta, theta, alpha, and beta frequency bands, and band-specific power envelopes are coupled with fNIRS-derived oxygenated haemoglobin (HbO) signals within predefined cortical regions of interest. A 10-second lag is applied to account for the delayed haemodynamic response following neural activity. Coupling is estimated using a general linear model. The area under the β-coefficient curve (β AUC) within the predefined analysis window is used to quantify cumulative EEG-fNIRS neurovascular coupling strength over time. Values are calculated separately for the predefined frequency bands and cortical regions of interest and compared between the distal transcutaneous electrical nerve stimulation and sham stimulation groups.

Secondary outcomes

  1. Pain VAS score

    Time frame: During colonoscopy, when the endoscope passes through the rectosigmoid junction, splenic flexure, and hepatic flexure.

    Pain intensity is assessed using a 10-cm Visual Analog Scale (VAS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Participants report their pain intensity at three predefined procedural stages during colonoscopy: passage of the endoscope through the rectosigmoid junction, splenic flexure, and hepatic flexure.

  2. EEG-Derived Cortical Neural Activity

    Time frame: During colonoscopy at predefined procedural stages, including anal intubation, splenic flexure, hepatic flexure, and ileocecal valve.

    Cortical neural activity is assessed using electroencephalography (EEG) during predefined stages of colonoscopy. After signal preprocessing and artefact removal, EEG activity is analysed in four predefined frequency bands: delta, theta, alpha, and beta. Outcome measures include relative spectral power, reflecting frequency-specific cortical activity, and pairwise EEG coherence, reflecting functional synchronization between cortical regions. Stage-specific changes relative to the corresponding resting-state reference and between-group differences are evaluated to characterize alterations in cortical neural activity and network organization associated with procedural visceral pain and distal transcutaneous electrical nerve stimulation.

  3. fNIRS-Derived HbO Cortical Activation

    Time frame: During colonoscopy, at predefined procedural stages including anal intubation, splenic flexure, hepatic flexure, and cecal intubation, within the prespecified post-event analysis window for each stage.

    Cortical activation is assessed using oxygenated haemoglobin (HbO) signals recorded by functional near-infrared spectroscopy (fNIRS). Event-related HbO responses are analysed using a general linear model within prespecified post-event time windows. Channel-wise β coefficients are estimated relative to position-matched resting-state recordings and are used to quantify the magnitude and direction of cortical HbO activation.

  4. fNIRS-Derived HbR Cortical Activation

    Time frame: During colonoscopy, at predefined procedural stages including anal intubation, splenic flexure, hepatic flexure, and cecal intubation, within the prespecified post-event analysis window for each stage.

    Cortical activation is assessed using deoxygenated haemoglobin (HbR) signals recorded by functional near-infrared spectroscopy (fNIRS). Event-related HbR responses are analysed using a general linear model within prespecified post-event time windows. Channel-wise β coefficients are estimated relative to position-matched resting-state recordings and are used to quantify the magnitude and direction of cortical HbR activation.

  5. fNIRS-Derived Cortical Functional Connectivity

    Time frame: During colonoscopy, at predefined procedural stages including anal intubation, splenic flexure, hepatic flexure, and cecal intubation.

    Cortical functional connectivity is assessed from fNIRS signals during predefined stages of colonoscopy. Functional connectivity between prespecified fNIRS channels or cortical regions is quantified using pairwise correlation coefficients to characterize stage-specific changes in cortical haemodynamic network organization. Connectivity measures are compared between the distal transcutaneous electrical nerve stimulation and control conditions.

  6. Colonoscopy time

    Time frame: during procedure (The total time to reach the three bends and to the ileocecal valve and for the entire examination was recorded)

Sponsors and collaborators

Lead sponsor

First Affiliated Hospital of the Chinese People's Liberation Army Naval Medical University

Other

Collaborators

  • Shanghai Shuli Intelligent Technology Co., Ltd

Registry information

Official study title

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

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Feb 7, 2025
Registry last updated
Aug 14, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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