Risk factors and preventative measures of early and persistent dysphagia after anterior cervical spine surgery: a systematic review

To conduct a systematic review of literature to determine risk factors and preventative measures of early and persistent dysphagia after anterior cervical spine surgery (ACSS). On March 2017, we searched the database PubMed, Medline, EMBASE, the Cochrane library, Clinical key, Springer link and Wiley Online Library without time restriction using the term 'dysphagia', 'swallowing disorders', and 'anterior cervical spine surgery'. Selected papers were examined for the level of evidence by published guidelines as level I, level II, level III, level IV studies. We investigated risk factors and preventative measures of early or persistent dysphagia after ACSS from these papers. The initial search yielded 515 citations. Fifty-nine of these studies met the inclusion and exclusion criteria. Three of them were level I evidence studies, 29 were level II evidence studies, 22 were level III evidence studies, and 3 were level IV evidence studies. Preventable risk factors included prolonged operative time, use of rhBMP, endotracheal tube cuff pressure, cervical plate type and position, dC2-C7 angle, psychiatric factors, tobacco usage, prevertebral soft tissue swelling, SLN or RLN palsy or injury of branches. Preventative measures included preoperative tracheal traction exercise, maintaining endotracheal tube cuff pressure at 20 mm Hg, avoiding routine use of rhBMP-2, use of zero-profile implant, use of Zephir plate, use of new cervical retractor, steroid application, avoiding prolonged operating time, avoiding overenlargement of cervical lordosis, decreasing surgical levels, ensuring knowledge of anatomy of superior laryngeal nerve and recurrent laryngeal nerve, to comfort always, patients quitting smoking and doctors ensuring improved skills. Unpreventable risk factors included age, gender, multilevel surgery, revision surgery, duration of preexisting pain, BMI, blood loss, upper levels, preoperative comorbidities and surgical type. Adequate preoperative preparation of the patients including preoperative tracheal traction exercise and quitting smoking, proper preventative measures during surgery including maintaining endotracheal tube cuff pressure at 20 mm Hg, avoiding routine use of rhBMP-2, use of zero-profile implant, use of Zephir plate, use of new cervical retractor, steroid application, avoiding prolonged operating time, avoiding overenlargement of cervical lordosis and decreasing surgical levels, doctors ensuring knowledge of anatomy, improved surgical techniques and to comfort always are essential for preventing early and persistent dysphagia after ACSS.