Laryngoscopic Screening Before Revision Anterior Cervical Spine Surgery : Is Vocal Cord Palsy a Relevant Factor in Deciding the Approach Direction?

Abstract

Study Design: Retrospective study. Objectives: The aim was to evaluate the exact incidence of vocal cord palsy (VCP) caused by previous anterior cervical spine surgery (ACSS) and aid surgeons in deciding the approach direction in revision ACSS. Summary of Background Data: The incidence of VCP detected by preoperative laryngoscopic screening before revision ACSS appeared to be much higher in previous reports than in our experience. Materials and Methods: We reviewed the data of 64 patients who underwent revision ACSS. Preoperative laryngoscopy was performed in all patients to detect VCP and/or structural abnormalities of the vocal cords. The patients' characteristics, laryngoscopy results, and symptoms before revision surgery that were potentially caused by previous recurrent laryngeal nerve injuries (voice change, foreign body sensation, and chronic aspiration) were recorded. Results: Laryngoscopy demonstrated no complete VCP or decreased vocal cord motility. Eleven patients (17.2%) showed vocal cord-related symptoms and 13 patients (20.3%) showed abnormal laryngoscopic findings without VCP. Four patients (6.2%) showed vocal cord-related symptoms and abnormal laryngoscopic findings simultaneously. At the initial operative level, no significant differences in vocal cord-related symptoms were observed between the upper and lower levels (C3-4-5 vs. C5-6-7). However, the frequency of vocal cord-related symptoms was significantly high at the larger number of levels (>= 3 segments) (P=0.010). Conclusions: In contrast to previous reports, this study demonstrated that VCP is rarely detected before revision ACSS. Therefore, deciding the approach direction with only vocal cord motility can be dangerous, and more attention is required in setting the approach direction in patients who show both vocal cord-related symptoms and abnormal laryngoscopic finding. In other cases, a contralateral approach which has a low risk of bilateral VCP could be utilized if necessary.