Hydrodissection Tunneling Technique on Recurrent Laryngeal Nerve Protection During Thyroidectomy (Huaxi Tunnel)

May 10, 2026 updated by: Yu Feng, West China Hospital

Effect of Hydrodissection Tunneling Technique on Recurrent Laryngeal Nerve Protection During Thyroidectomy: A Multicenter, Randomized Clinical Trial

Protection of the recurrent laryngeal nerve (RLN) is a key focus and difficulty in thyroid surgery. Unilateral RLN injury can lead to ipsilateral vocal cord paralysis, resulting in hoarseness in patients postoperatively. Bilateral RLN injury, however, may cause bilateral vocal cord paralysis, leading to dyspnea and even asphyxiation; in severe cases, tracheotomy and permanent tracheal cannulation are required. Consequently, RLN injury significantly impacts patients' postoperative quality of life and career development. Guidelines and consensuses both domestically and internationally recommend that during the management of the posterior thyroid capsule, active detection, exposure, and dissection of the RLN, combined with meticulous capsular dissection along the RLN, should be performed to effectively reduce the incidence of RLN injury. While active anatomical identification of the RLN can clarify the nerve branches and their relationship with surrounding tissues, facilitating surgical procedures such as ligation and hemostasis, the traditional method of dissecting with instruments like hemostats or right-angle forceps (either blunt or sharp dissection along the nerve surface) increases the risk of nerve injury due to traction, clamping, or thermal damage. This is particularly challenging for less experienced surgeons, who face great difficulties in using energy devices near the RLN without causing injury-a major concern in the field of thyroid surgery.

Diluted epinephrine solution exhibits excellent hemostatic effects in local surgery, improves surgical field clarity, and shortens operation time. Its safety has been clinically verified, and it is commonly used in plastic and cosmetic surgery, joint surgery, and the cavity creation process of endoscopic thyroid surgery. Based on this, this study innovatively proposes the "Huaxi Tunnel Technique": on the basis of meticulous posterior capsular dissection in traditional thyroid surgery, the RLN detection point on the posterior capsule below the lower pole of the thyroid is located using the "cross method" and exposed. A syringe containing diluted epinephrine solution is then used, with its front hose inserted along the RLN towards the laryngeal entry direction. Rapid injection is performed, and the pressure generated by this injection separates the fibrous connective tissue on the RLN surface, forming a "tunnel" from the RLN detection point to the laryngeal entry site-thus achieving exposure and dissection of the RLN.

This technique offers multiple advantages: epinephrine reduces local bleeding, enhancing surgical safety and the convenience of meticulous capsular dissection; tunnel formation causes edema and discoloration of the fibrous connective tissue in the posterior thyroid capsule (while the parathyroid glands remain uncolored), facilitating the rapid identification and protection of the parathyroid glands. Preliminary preclinical experiments have confirmed that the technique reduces the difficulty of RLN exposure and dissection, decreases intraoperative bleeding and complication rates, and improves the safety of thyroid surgery. To further evaluate the efficacy, safety, and operability of this tunnel technique for RLN exposure and dissection, a prospective single-blind randomized controlled trial comparing it with traditional thyroid surgery methods is hereby conducted.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

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Detailed Description

This study is a multicenter, single-blind, randomized controlled trial. Eligible patients will be randomly assigned in a 1:1 ratio to either the experimental group (hydrodissection tunneling technique) or the control group (conventional dissection technique).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

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238

Phase

Phase

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  • Not Applicable

Contacts and Locations

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Study Contact

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Study Contact Backup

Study Locations

  • China
    • Sichuan
      • Chengdu, Sichuan, China, 610041
        • West China Hospital of Sichuan University

Participation Criteria

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Eligibility Criteria

Eligibility Criteria

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Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

Aged 18-75 years, regardless of gender Patients hospitalized for open thyroid surgery (undergoing at least unilateral lobe and isthmus resection) and undergoing the procedure for the first time Preoperative color Doppler or contrast-enhanced ultrasound assessment indicates no significant invasion of the recurrent laryngeal nerve by the lesion Participants voluntarily agree to join the trial and provide signed informed consent.

Exclusion Criteria:

History of thyroid nodule ablation therapy Patients scheduled for lateral neck dissection History of hypertension, atrial fibrillation, or severe arrhythmia Uncontrolled subacute thyroiditis or hyperthyroidism Severe comorbidities affecting major organs (cardiac, pulmonary, hepatic, or renal) Presence of cancer-related cachexia syndrome History of psychiatric disorders or cognitive impairment Pregnant or lactating women Participation in other clinical trials within 90 days Other conditions deemed by investigators as unsuitable for trial participation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
No Intervention: Control group
Control group (conventional group): the group in which the recurrent laryngeal nerve was exposed and the thyroid gland was resected by standard thyroid surgical techniques.
Experimental: Hydrodissection tunneling technique

Experimental group (Hydrodissection tunneling technique):

A 5-ml syringe was loaded with adrenaline solution diluted in normal saline (1 mg adrenaline in 250 ml saline, concentration 4 µg/ml) and fitted with a 2-3 cm soft extension tube as the injection tip. After the recurrent laryngeal nerve (RLN) was identified by the cross-hatch method at the posteroinferior capsule below the lower pole of the thyroid gland, the solution was rapidly injected along the RLN's course toward its laryngeal entry point. The hydraulic pressure created by this rapid injection separated the fibrous connective tissue surrounding the nerve, forming a tissue tunnel from the initial identification site to the laryngeal entry point. Subsequent nerve dissection was then performed within this tunnel.
Procedure: Hydrodissection tunneling technique
A 5-ml syringe was loaded with adrenaline solution diluted in normal saline (1 mg adrenaline in 250 ml saline, concentration 4 µg/ml) and fitted with a 2-3 cm soft extension tube as the injection tip. After the recurrent laryngeal nerve (RLN) was identified by the cross-hatch method at the posteroinferior capsule below the lower pole of the thyroid gland, the solution was rapidly injected along the RLN's course toward its laryngeal entry point. The hydraulic pressure created by this rapid injection separated the fibrous connective tissue surrounding the nerve, forming a tissue tunnel from the initial identification site to the laryngeal entry point. Subsequent nerve dissection was then performed within this tunnel.
Other Names:
  • adrenaline

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
The incidence of significant amplitude reduction (SAR) events of RLN
Time Frame: Intraoperative
SAR was defined as a 50% or greater decrease in electromyographic amplitude from the initial baseline at 1.0-mA or 3.0-mA stimulation.
Intraoperative

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Recurrent laryngeal nerve injury signal amplitude
Time Frame: Intraoperative
Differences in nerve signal amplitude before and after RLN dissection at 1 mA and 3 mA.
Intraoperative
Assessment of bleeding during RLN dissection
Time Frame: Intraoperative
After the nerve is identified, a dry gauze is placed; the difference in gauze weight before and after nerve dissection is used to quantify blood loss.
Intraoperative
Duration of RLN dissection
Time Frame: Intraoperative
The time point immediately before and immediately after nerve dissection are recorded, and the interval is calculated as the time required for RLN dissection.
Intraoperative
Assessment of parathyroid gland identification and preservation
Time Frame: Preoperative, Intraoperative, 1 day postoperative, 1 month postoperative
The evaluation is carried out in four domains: (1)Vascularity of the preserved parathyroid glands;(2) Surgeon's subjective rating of parathyroid recognizability during operation (poor / fair / good);(3) Intra-operative autotransplantation of parathyroid tissue (number of fragments transplanted);(4)Change in serum PTH and calcium levels from pre-operative to post-operative measurements
Preoperative, Intraoperative, 1 day postoperative, 1 month postoperative
VHI-10
Time Frame: The day before surgery, 1 day postoperative
A voice disorder index scale consisting of 10 items, including 5 functional items, 3 physical items, and 2 emotional items. Each item is scored from 0 to 4, with different scores representing the frequency of occurrence: "never" = 0; "rarely" = 1; "sometimes" = 2; "often" = 3; and "always" = 4. A higher score indicates a greater impact of voice disorders on that aspect and a more severe self-assessment of voice impairment. The critical value for VHI is 8 points, and individuals with a VHI score ≥ 8 are considered to have voice dysfunction. Patients need to complete the VHI-10 questionnaire before surgery and on the first day after surgery.
The day before surgery, 1 day postoperative
V-RQOL questionnaire
Time Frame: The day before surgery, 1 day postoperative
Voice-Related Quality of Life-10 (V-RQOL-10): Comprising 10 items, it includes two dimensions: social-emotional and physical-functional. The content of the items describes the subjective experiences of patients with voice disorders. Severity is rated on a scale of 1 to 5, where 1 represents "not at all," 2 represents "a little," 3 represents "a moderate amount," 4 represents "a lot," and 5 represents "extremely." This questionnaire uses "reverse scoring" and must ultimately be converted to a range of 0 to 100 points. A higher overall score indicates better voice quality, while a lower score indicates poorer voice quality.Patients need to complete the V-RQOL questionnaire before surgery and on the first day after surgery.
The day before surgery, 1 day postoperative
Total operative time
Time Frame: Intraoperative
The interval from skin incision to skin closure is recorded to evaluate the impact of the different surgical techniques on overall procedure length.
Intraoperative
Postoperative drainage volume
Time Frame: 1 day postoperative, 2 days postoperative, 3 days postoperative, 4 days postoperative
The total drain output before removal is recorded to assess the impact of the different surgical techniques on overall postoperative drainage.
1 day postoperative, 2 days postoperative, 3 days postoperative, 4 days postoperative
Assessment of local epinephrine-related adverse effects
Time Frame: The day before surgery, Intraoperative, 1 day postoperative

Pre-operative and first post-operative day heart rate is recorded, together with the highest intra-operative HR values, to evaluate side-effects of topical epinephrine use.

Baseline data including history of arrhythmia is also registered.
The day before surgery, Intraoperative, 1 day postoperative

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
West China Hospital

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Sichuan Provincial People's Hospital
West China Tianfu Hospital
Shang Jin Hospital of West China Hospital,Sichuan University
Sanya People's Hospital
Sun Yat-Sen University Cancer Center

Publications and helpful links

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General Publications

Study record dates

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Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 1, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 1, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 22, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 21, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 23, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 13, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 10, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2026

More Information

Terms related to this study

Keywords

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Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2024（2498）

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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