NERVE MONITORING IN THYROID SURGERY: A RETROSPECTIVE COHORT STUDY

Background:The proximity of the Recurrent Laryngeal and External Branch of Superior Laryngeal Nerve to the Thyroid Gland has been a key factor for a profound interest of surgeons and clinicians in the clinical outcomes and Vocal changes in the post operative period in the patients undergoing thyroid surgery. The presence of Recurrent Laryngeal nerve in proximity of Thyroid poses a significant risk of damage to the nerve during surgery. The Recurrent Laryngeal Nerve SuppliesLarynx below the level of vocal cords and all the muscles except Cricothyroid. Posterior Cricoarytenoid, the only abductor of vocal cord is also supplied by this nerve. So, any damage to the nerve during surgery causes significant changes in pitch and texture of voice, commonly referred to as hoarseness.Intra-operative Nerve Monitoringwas introduced about 50 years ago and various neuromonitoring methods (glottis pressure method, glottic monitoring method, insertion of needle electrodes invocal cords endoscopically or through cricothyroid membrane, laryngeal palpationmethod, and monitoring via endotracheal tube with surface electrodes) have been utilized. We present a retrospective cohort study to surmise the effect of the use of Intraoperative nerve monitoring devices during Thyroid surgery and compare the clinical outcome in two cohorts. First, the study group where the nerve monitoring was used intraoperatively and the Second, where no intraoperative nerve monitoring was used. All the Patients included in the study underwent Thyroid surgery in the Department of Otorhinolaryngology-Head and Neck Surgery, MBS Hospital, Kota. Methods:This retrospective cohort study includes 100 patients as per the inclusion criteria specified in this article and all the included patients were studied after dividing them into two groups with one group where intraoperative nerve monitoring was used and the other group where no nerve monitoring was used. Each group had 50 patients each. All the patients are regularly documented for with Video Laryngoscopic Examination as a standard. All the data collected from the archives and put to statistical evaluation to analyse the data Age wise, Sex wise, Residential address wise, according to mean Thyroid volume, according to presenting complaints, according to history, according to mean operative time, according to the type of Nerve Injury, according to duration of hospital stay and other parameters as followed in the study. Results: On appropriate statistical analysis of the data, it was seen that there were no demographic variables within groups that ensured statistical similarity in the groups, there was also no statistical correlation of functional preservation attributable to mean Thyroid volume. The incidence of nerve injury was higher in the patients who got themselves operated for the malignancy of thyroid and the revision surgeries. The patients being operated for controlled toxic goitre reported ni nerve injury in the post operative period. The intraoperative nerve monitoring reported lower mean time required to do the surgery. There was a similar incidence of permanent and transient nerve injury in both the cohort groups.