Ultrasound Prediction For Vocal Cord Dysfunction In Patients Scheduled For Anterior Cervical Spine Surgeries

1. Design: A prospective cohort study. 2. Sample size: Assuming that the target population is 240 and positive predictive value of transcutaneous laryngeal ultrasonography is 89.4%. So, the sample size is 91 cases using OPEN Source Epidemiologic Statistics for Public Health (OPENEPI) with confidence interval 95% and power of test is 80%. All patients underwent transcutaneous laryngeal ultrasonography examination by both anterior and lateral approach of the Vocal Cords (VCs) before the surgery, immediately after extubation, 2 h, 12h, 24 and 48hour postoperatively by an anesthesiologist with an experience of at least three years in ultrasonography scan.