Can we predict postoperative dysphagia after anterior cervical discectomy and fusion based on lateral x-ray? An external validation of two outcome scores.

Postoperative dysphagia following Anterior cervical discectomy and fixation (ACDF) impacts quality of life and risks airway complications. Identification of retropharyngeal oedema with a lateral Xray has gained interest as screening method. We prospectively evaluated the relation between dysphagia and two radiological scores to determine the external predictive value. A prospective study (2021-2022) held in a tertiary centre, including a sequential sample of patients operated of ACDF for degenerative conditions. Postoperative (day + 1) evaluation of dysphagia was systematically performed by a speech and language therapist. The retropharyngeal swelling index (by Haws) and the dysphagia predicting score (by Yoshida) were calculated on lateral Xray. A logistic regression model and receiver operating characteristic (ROC) curves were calculated. 100 patients were included for analysis, of which 26% developed postoperative dysphagia (mild in 20% and mild-to-moderate in 6%). The most frequent form of dysphagia was oesophageal (18%), followed by oropharyngeal (4%) and pharyngoesophageal (3%). None of the potential risk factors studied were confirmed in our sample. For predicting oropharyngeal dysphagia, Yoshida score yielded an AUROC of 0.730 and the sweeling index an AUROC of 0.530. Conversely, in cases of oesophageal dysphagia, the AUROC were 0.590 and 0.504 respectively. From our data, it may be inferred that oropharyngeal and oesophageal dysphagia might harbour different underlying mechanisms, still not well understood. The use of a simple X-ray may become a routine screening step for patients undergoing ACDF. While it seems robust to predict oropharyngeal dysphagia, identification of oesophageal dysphagia may require further investigation.