**2. Incidence and prevalence**

Postoperative dysphagia is the most common complications following ACSS, the incidence ranges between 1 and 79% [1, 11, 13]. The criteria used to define and detected dysphagia may influence the reported incidence, many factors impact the exact incidence which include:


The incidence ranges between 28 and 57% in the intermediate and long term postoperative period (1–6 weeks), [17, 22], Riley et al. on a multicentric study that enrolled 454 patient who underwent ACSS in a multicentric study between 1998 and 2001 found that the incidence of postoperative dysphagia was 28.2, 6.8 and 7.8% at 3, 6, and 24 months, respectively, and at both 6 and 24 months the prevalence rate of persistent dysphagia was 21% [21]. On another study, the average incidence varied along the post-operative time after ACSS: 53.2% at 1 month, 31.6% at 2–4 months, 19.8% at 6 months, 16.8% at 12 months and 12.9 at 24 months [11].

Lee et al. reported an overall prevalence rate of postoperative dysphagia over time as the following: 54.0% at 1 month; 33.6% at 2 months; 18.6% at 6 months; 15.2% at 1 year; and 13.6% at 2 years [19].

Later, Riley et al. in a systematic review found that the incidence of postoperative dysphagia decreased with time after surgery and reach plateau at rate of 13–21% at one year [1].
