The occurrence of postoperative dysphagia after cervical spinal surgery in several studies ranged from from 4%-71%1–25. In recent years, similar studies have been reported in China. These differences in the occurrence of dysphagia may be related to inclusion criteria, the design scheme and statistical method. In this study, the occurrence of dysphagia was 12.8% of patients in ACDF group and 9.4% in PC group. Dysphagia most commonly begins in the immediate postoperative period, but may also be delayed, beginning more than 4 weeks after surgery in some patients. Most cases are mild and resolve within 1 week. In a small subset of patients, these symptoms are permanent. Despite this, dysphagia has no significant impact on patient satisfaction with surgery.
A total of 354 patients were followed up by researcher in this study, including 172 patients of AC group and 182 patients of PC group. The results showed that dysphagia was 12.8% and 9.4% after AC and PC procedure in the early postoperative period. Symptoms then decreased to 9.3% and 6.0% at 1 month, 7.0% and 4.4% at 3 month, 4.6% and 2.2% at 6 months, 3.5% and 1.6% at 12 months separately in the AC and PC group. No significant difference was found between AC and PC group in the incidence and severity of dysphagia early postoperatively or at any follow-up time after surgery. Since the incidence of postoperative dysphagia was nearly the same between these two groups, we hold the belief that the procedure type was not the key factor in the mechanism of developing dysphagia. Most of the improvement occurred in the first 3 months postoperatively. Most of the dysphagia was graded as ‘‘mild’’ and ‘‘moderate’’. Only 1.1% of patients at 1 year after cervical surgery had dysphagia that was graded as severe (Table 2).
Swallowing requires precise coordination of neuromuscular events in different organs, including oral, pharynx, laryngeal and esophagus10. The process of swallowing is divided into four parts: the first two named as oral pre-phase and oral phase, are voluntary movements involuntary dominated by human awareness; the last two named as throat phase and esophageal phase are involuntary movements. In cervical spinal surgery, Total or partial neuromuscular dysfunction during any stage of these parts may lead to the symptom of dysphagia after operation.
The mechanisms of postoperative dysphagia development after cervical spine surgery is currently under investigation. Masahiko Miyata3–4 and Neo reported that excessive change in O-C2 angle at occipital-cervical fusion may result in reduction of the oropharyngeal volume, leading to severe dysphagia and even respiratory distress after operation. Michael-Johns5 considered postoperative dysphagia might be related to the throat phase that was divided into five segments, including epiglottis closure, retraction of the base of tongue, extrusion downwards of pharynx, closure and lift of laryngeal, and eventually relaxion of the upper esophageal sphincter. Cloward et al 6 suggested that some degree of dysphagia is experienced by all patients after cervical operation.
To assess whether reported risk factors affected the occurrence of dysphagia, we collected clinical and operative characteristics. Logistic regression was performed in analyzing these clinical data, including gender, age, BMI, operation time, blood loss, type of surgical procedure (anterior/posterior), revision surgery, number of surgical segments, the superior segment of surgical cite, usage time of neck collar, whether the third cervical vertebrae was included. No direct association was observed between these data and postoperative dysphagia. But we find that long term use of neck collar may lead to postoperative dyaphagia(Table 3). That may partly because neck fixation for so long time is not conductive to eating and drinking. So we suggest that neck collar should be worn no longer than four weeks after cervical spine surgery.
The assessments of dysphagia in this retrospective study were based on the subjective experience by patients. Most patients presented with dysphagia after operation lack anatomical examinations such as barium meal test, and laryngoscopy18. In the future, prospective studies with larger samples are required to achieve more reliable conclusions. They can further provide guidance for surgical approach and lower the rate of postoperative complications.