The related factors of dysphagia after anterior cervical discectomy and fusion with the Zero-profile implant system

English Keywords:Cervical spondylosis  Anterior cervical discectomy and fusion  Zero-P  Dysphagia  Related factors

English Abstract:

  【Abstract】 Objectives: To investigate the related factors of dysphagia after anterior cervical discectomy and fusion with the zero-profile implant system. Methods: A retrospective analysis of 115 patients who had undergone Zero-P implant system interbody fusion surgery and followed up for at least one year was performed from January 2011 to December 2016, including 66 males and 49 females. The Bazaz scoring system was used to assess the degree of dysphagia by telephone or outpatient follow-up. All patients were divided into non-dysphagia group and dysphagia group (light, moderate, and severe dysphagia patients) according to the presence or absence of postoperative dysphagia to explore the effect of the age, gender, body mass index(BMI), diabetes mellitus, hypertension, smoking, alcohol consumption, intraoperative time, estimated blood loss, prevertebral soft-tissue swelling, postoperative O-C2 angle, postoperative C2-7 angle, the highest segment of surgery and the number of surgical segments. At the same time, the effect of postoperative C2-7 angle was mainly discussed. The student t-test and a chi-squared test were conducted for continuous and categorical data, respectively. The Spearman′s correlation coefficient was conducted between the degree of dysphagia and postoperative C2-7 angle. To eliminate the influence of confounding factors, ordinal logistic regression was performed for multifactor regression of factors which had a P value less than 0.2 in the single factor analysis. Results: There were 18 patients(11 males and 7 females) in the dysphagia group; 97 patients(55 males and 42 females) in the non-dysphagia group. Significant correlation was showed with the comparison of age, postoperative C2-7 angle, postoperative O-C2 angle and prevertebral soft-tissue swelling between two groups(P<0.05). There was no significant correlation between age, BMI, estimated blood loss and postoperative dysphagia(P>0.05). The factors with P value less than 0.2 in the single factor analysis included age, BMI, estimated blood loss, postoperative O-C2 angle, postoperative C2-7 angle and prevertebral soft-tissue swelling. Logistic regression analysis showed that the postoperative C2-7 angle and prevertebral soft-tissue swelling were significantly associated with postoperative dysphagia(P<0.05). In the dysphagia group, the C2-7 angle was 9.17°-36.39°, with an average of 19.14°±6.73°. In the asymptomatic group, the C2-7 angle was 1.59°-20.45°, with an average of 10.88°±5.36°. The average postoperative C2-7 angle was significantly greater in the patients with dysphagia than in the non-dysphagia group(P<0.05). Compared the incidence of dysphagia(3.7%, 2/54) when C2-7 angle<12° with the incidence of dysphagia when C2-7 angle≥12°(26.2%, 16/61), the difference was statistically significant(P<0.05). Spearman′s correlation coefficient of the dysphagia group(18 patients, mild: 16; moderate: 0; severe: 2) between degree of dysphagia and incidence of postoperative dysphagia showed no significant correlation. Conclusions: The postoperative C2-7 angle and prevertebral soft-tissue swelling has an important effect on the occurrence of dysphagia in patients undergoing anterior cervical discectomy and fusion with the zero-profile implant system. Paying attention to the adjustment of the C2-7 angle during surgery and the control of prevertebral soft-tissue swelling may reduce the incidence of postoperative dysphagia.