Atrophy of the Posterior Cricoarytenoid Muscle as an Indicator of a Recurrent Laryngeal Nerve Injury History Before Revision Anterior Cervical Spine Surgery

Study Design: Retrospective study. Objectives: In our recent study, we observed some cases of symptomatic normal vocal cord motility instead of asymptomatic vocal cord palsy (VCP) in preoperative laryngoscopy of a revision anterior cervical spine surgery (ACSS) cohort. We assumed the intrinsic muscle atrophy caused by recurrent laryngeal nerve injury could cause vocal cord-related symptoms. Thus, radiological examinations were reviewed in relation to the posterior cricoarytenoid (PCA) muscle, one of the intrinsic muscles. Methods: We retrospectively analyzed 64 patients who underwent a revision ACSS. Patients with vocal cord-related symptoms were classified as symptomatic group (group S, n = 11), and those without symptoms as asymptomatic group (group AS, n = 53). The bilateral size and signal intensity of the PCA muscles in these patients were measured in the axial view with preoperative computed tomography (CT) and magnetic resonance imaging (MRI) evaluations. Since the size and signal intensity values were different on each image, the ratios of the contralateral and ipsilateral muscle values were analyzed for each modality. Results: There was no VCP on laryngoscopy study. However, the mean ratio of the PCA muscle size on CT was 1.40 +/- .37 in group S and 1.02 +/- .12 in group AS (P = .007). These values on the MRI were 1.49 +/- .45 in group S and 1.02 +/- .14 in group AS, which was also a significant difference (P = .008). Conclusions: Evaluating the size of the PCA muscle before revision ACSS may predict a previous recurrent laryngeal nerve injury. Careful planning for the appropriate approach should be undertaken if vocal cord-related symptoms and atrophy of PCA muscle are evident.