Predictive ability of pharyngeal inlet angle for the occurrence of postoperative dysphagia after occipitocervical fusion

Lin-Nan Wang,Xi Yang,Chun-Guang Zhou,Li-Min Liu,Bo-Wen Hu,Yue-Ming Song,Lei Wang

doi:10.1186/s12891-020-03921-y

Abstract

BackgroundPIA has been proven to be a predictor for postoperative dysphagia in patients who undergo occipitospinal fusion. However, its predictive effect for postoperative dysphagia in patients who undergo OCF is unknown. The aim of this study was to evaluate the predictive ability of the pharyngeal inlet angle (PIA) for the occurrence of postoperative dysphagia in patients who undergo occipitocervical fusion (OCF).MethodsBetween 2010 and 2018, 98 patients who had undergone OCF were enrolled and reviewed. Patients were divided into two groups according to the presence of postoperative dysphagia. Radiographic parameters, including the atlas-dens interval (ADI), O-C2 angle (O-C2a), occipital and external acoustic meatus to axis angle (O-EAa), C2 tilting angle (C2Ta), C2-7 angle (C2-7a), PIA and narrowest oropharyngeal airway space (nPAS), were measured and compared. Simple linear regression and multiple regression analysis were used to evaluate the radiographic predictors for dysphagia. In addition, we used PIA = 90° as a threshold to analyze its effect on predicting dysphagia.ResultsOf the 98 patients, 26 exhibited postoperative dysphagia. Preoperatively, PIA in the dysphagia group was significantly higher than that in the nondysphagia group. We detected that O-C2a, O-EAa, PIA and nPAS all decreased sharply in the dysphagia group but increased slightly in the nondysphagia group. The changes were all significant. Through regression analyses, we found that PIA had a similar predictive effect as O-EAa for postoperative dysphagia and changes in nPAS. Additionally, patients with an increasing PIA exhibited no dysphagia, and the sensitivity of PIA <90° in predicting dysphagia reached 88.5%.ConclusionsPIA could be used as a predictor for postoperative dysphagia in patients undergoing OCF. Adjusting a PIA level higher than the preoperative PIA level could avoid dysphagia. For those who inevitably had decreasing PIA, preserving intraoperative PIA over 90° would help avert postoperative dysphagia.Trial registrationThis trial has been registered in the Medical Ethics Committee of West China Hospital, Sichuan University. The registration number is 762 and the date of registration is Sep. 9 th, 2019.

Highlights

pharyngeal inlet angle (PIA) has been proven to be a predictor for postoperative dysphagia in patients who undergo occipitospinal fusion
When comparing the postoperative values, we found that postoperative O-C2 angle (O-C2a), occipital and external acoustic meatus-to-axis angle (O-EAa), PIA and narrowest oropharyngeal airway space (nPAS) were significantly lower in the dysphagia group than in the nondysphagia group
Morizane et al promoted a new parameter, O-EAa, which could reflect the change in atlantooccipital angle and the translational motion of the atlas [7]. They proved that O-EAa was superior to OC2a in predicting changes in nPAS for atlantoaxial subluxation (AAS) patients [19]. We evaluated this angle for all occipitocervical fusion (OCF) patients and found that the predictive ability of O-EAa surpassed that of O-C2a in postoperative dysphagia [4]

Summary

Introduction

PIA has been proven to be a predictor for postoperative dysphagia in patients who undergo occipitospinal fusion. The aim of this study was to evaluate the predictive ability of the pharyngeal inlet angle (PIA) for the occurrence of postoperative dysphagia in patients who undergo occipitocervical fusion (OCF). Dysphagia is one of the most commonly seen complications after occipitocervical fusion (OCF), with an incidence ranging from 15.8–26.6% [1–4] Most of these patients have a protracted course, and dysphagia interferes with the quality of daily living [3–6]. For this reason, the relationship between postoperative dysphagia and changes in occipitocervical alignment has been studied by many researchers, and several predictors have been promoted [1, 3–5, 7, 8]. We reviewed 109 OCF patients and found that O-EAa was superior to OC2a in predicting decreases in oropharyngeal space and postoperative dysphagia [4]. During the measurement of O-EAa, we found it difficult to identify the external acoustic meatus in some patients

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