Renovated Prediction Model for Difficult Transoral and Submental Endoscopic Thyroidectomy

A Functional-oriented Modification of TOaST Based on Partial Preservation of the Lines Alba Cervical

The investigators have previously proposed a prediction model for difficult transoral and submental thyroidectomy through a retrospective study. In order to better promote transoral and submental endoscopic approach for thyroid surgery and to set up an appropriate training course, the investigators aim to refine the procedure through a prospective study.

Study Overview

• Status: Recruiting
• Conditions: Thyroid Diseases; Thyroid Cancer; Thyroid Nodule
• Intervention / Treatment: Procedure: Modified TOaST with caudal linea alba preservation

Detailed Description

This study is a prospectively registered cohort study evaluating postoperative neck functional recovery after TOaST. As a procedure refinement, the study will further evaluate whether partial preservation of the caudal linea alba cervicalis during TOaST is associated with improved postoperative neck functional recovery without compromising surgical exposure or central compartment dissection.

The main purpose of this technical refinement is to determine whether preserving the caudal anterior cervical fascial continuity may reduce postoperative anterior neck tightness, swallowing-related traction discomfort, pain, and limitation of neck range of motion. Surgical feasibility and safety will be assessed using operative time, intraoperative blood loss, drainage volume, number of central lymph nodes retrieved, recurrent laryngeal nerve events, parathyroid-related outcomes, postoperative complications, and the rate of technical conversion.

In addition, male sex, age, BMI, neck length and certain thyroid disease such as thyroiditis and hyperthyroidism have been long cited as indicators of a difficult TOaST. The investiagtors hypothesized that neck extension was critical to the exposure and visualization of the surgical field in the endoscopic thyroidectomy. Therefore, several measurements were innovatedly integrated into the prediction model, including neck circumference, thyromental distance, sternomental distance, ratio of height-to-thyromental distance, ratio of height-to-sternomental distance.

• Study Type: Observational
• Enrollment (Estimated): 300

Contacts and Locations

• Study Contact: Name: Ling Zhan, Doctor; Phone Number: 08615821120972; Email: rebecca0428zhan@163.com

Study Locations

• China
  • Shanghai, China, 200233
    • Recruiting
    • Shanghai Sixth People's Hospital
    • Contact: Ling Zhan, Doctor; Phone Number: 08615821120972; Email: 15821120972@163.com

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Patients with FNA proven differentiated thyroid cancer, were willing to undergo thyroidectomy and central lymph node dissection via transoral and submental approach. Patients were well informed about the transoral and submental approach and were aware of the potential benefits and risks. Patient consented for us to use perioperative data.

Description

Inclusion Criteria:

• Clinical diagnosis of differentiated thyroid cancer with a maximum diameter not exceeding 4 cm
• Clinical diagnosis of benign thyroid nodule with a maximum diameter not exceeding 6 cm
• Absence of suspicious lateral lymph nodes or distant metastases

Exclusion Criteria:

• Participants with fusion or fixation of lymph nodes in the neck
• Participants with history of neck surgery or radiation
• Participants with vocal fold fixation by preoperative fibrolaryngoscope
• Participants with preoperative examination suggestive of extrathyroidal invasion
• Participants with a significantly restricted neck and/or jaw

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Conventional TOaST with bilateral strap muscle suspension; Participants undergoing conventional transoral and submental thyroidectomy. In this group, the linea alba cervicalis is opened caudally toward the suprasternal notch to establish the operative working space. Bilateral symmetric suspension of the strap muscles is performed to standardize surgical exposure.
Modified TOaST with caudal linea alba preservation; Participants undergoing modified transoral and submental thyroidectomy. In this group, the linea alba cervicalis is opened only in its cranial portion, with intentional preservation of a visible caudal linea alba-strap muscle fascial bridge. Bilateral symmetric suspension of the strap muscles is performed to create a centered operative window. If exposure is inadequate, the caudal linea alba opening may be extended and the case will be recorded as technical conversion to conventional TOaST.	Procedure: Modified TOaST with caudal linea alba preservation; The modified procedure consists of cranial limited opening of the linea alba cervicalis with intentional preservation of the caudal linea alba-strap muscle fascial bridge. Bilateral symmetric suspension of the strap muscles is performed to maintain a centered operative window for thyroid lobectomy and, when indicated, ipsilateral central compartment lymph node dissection. If exposure is inadequate, the caudal linea alba may be further opened for safety.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative neck functional recovery at 1 month	Postoperative neck functional recovery will be assessed 1 month after surgery using a standardized neck function assessment, including neck discomfort, anterior neck tightness, swallowing-related traction discomfort, and neck range of motion. Higher impairment scores indicate worse neck functional recovery.	1 month after surgery
Anterior neck tightness score	Anterior neck tightness will be assessed using a patient-reported visual analog scale or numerical rating scale. Higher scores indicate more severe tightness.	Postoperative 1 week, 1 month, and 3 months
Swallowing-related traction discomfort	Swallowing-related traction discomfort will be assessed using a patient-reported visual analog scale or numerical rating scale. Higher scores indicate more severe discomfort.	Postoperative 1 week, 1 month, and 3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
degree of pain	pain intensity was assessed using a standard visual analogue score, with a score of 0 to 10 corresponding to no pain to the most severe pain	approximately 4 hours after surgery and on postoperative day 1
hospitalization	days of hospitalization	Length of stay from hospitalisation to discharge
Number of participants with recurrent laryngeal nerve injury	Impaired vocal cord mobility confirmed by postoperative laryngoscopy	Through study completion, an average of 1 year
Number of participants with hypoparathyroidism	A postoperative parathyroid hormone level of less than 10 pg/ml	Through study completion, an average of 1 year
Operative time	Operative time was defined as the duration from incision to closure, and was collected from anesthesia record sheet	Immediately at the end of the surgery
Central compartment lymph node yield	For participants undergoing central compartment lymph node dissection, the number of retrieved central compartment lymph nodes will be recorded and compared between groups.	At the time of pathological assessment after surgery

Collaborators and Investigators

• Sponsor: Shanghai 6th People's Hospital
• Investigators: Principal Investigator: Ling Zhan, Doctor, Shanghai 6th People's Hospital

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2024
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: December 11, 2024
• First Submitted That Met QC Criteria: December 13, 2024
• First Posted (Actual): December 18, 2024

Study Record Updates

• Last Update Posted (Actual): August 10, 2026
• Last Update Submitted That Met QC Criteria: August 5, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: Prediction model; Endoscopic thyroidectomy; Transoral and submental approach
• Additional Relevant MeSH Terms: Endocrine System Diseases; Neoplasms by Site; Neoplasms; Endocrine Gland Neoplasms; Head and Neck Neoplasms; Thyroid Diseases; Thyroid Nodule; Thyroid Neoplasms
• Other Study ID Numbers: 2025-KY-029(K)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Data are available on request due to privacy or other restrictions. The data that support the findings of this study are available on request from Ling Zhan. The data are not publicly available due to them containing information that could compromise research participant privacy.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No