Systematic Postdissection Vagal Stimulation and Surgical Strategy During Thyroidectomy.

Area of Science:

• Otolaryngology
• Surgical Neurology
• Endocrinology

Background:

• Intraoperative neuromonitoring (IONM) is vital for preventing vocal cord palsy during thyroidectomy.
• The International Nerve Monitoring Study Group recommends a specific sequence for recurrent laryngeal nerve (RLN) stimulation.
• The utility of V2 (postdissection vagus nerve) stimulation in identifying postoperative vocal cord palsy requires further investigation.

Purpose of the Study:

• To evaluate the sensitivity of V2 stimulation compared to R2 stimulation alone for detecting postoperative vocal cord palsy.
• To assess the role of systematic V2 stimulation in minimizing the risk of bilateral vocal cord palsy after total thyroidectomy.

Main Methods:

• Retrospective cross-sectional study of patients undergoing thyroidectomy with IONM (V1, R1, R2, V2 sequence).
• Comparison with a historical cohort using selective vagal nerve stimulation.
• Primary outcome: vocal mobility on postoperative day 1; analysis of sensitivity, specificity, PPV, and NPV.

Main Results:

• V2 stimulation demonstrated 100% sensitivity for detecting postoperative vocal cord palsy, compared to 57.9% for R2 stimulation.
• 9 cases with intact R2 and absent V2 response showed 77.8% impaired vocal mobility.
• Systematic V2 stimulation showed higher sensitivity (100%) for IONM compared to selective vagal nerve stimulation (83.3%) in prior studies.

Conclusions:

• IONM without systematic V2 stimulation has inferior sensitivity in detecting vocal cord palsy.
• Systematic V2 stimulation is a more sensitive method for identifying potential nerve injury during thyroidectomy.
• Systematic V2 stimulation should be considered the criterion standard to reduce the risk of bilateral vocal cord palsy.