Table 4. Causes of oropharyngeal dysphagia according to operative approach and operative technique.

Approach/technique	Possible resulting condition
Operative approach (anterior)
Dissection or retraction	Damage of the aerodigestive pathway38; muscle and serosa injuries and edema20; tissue damage with subsequent edema13; bruising or laceration of tissues38 SLN injury,29 most at risk with surgery involving C3-C4,5 15 42 which can cause laryngeal sensory impairment5 Injuries to the pharyngeal plexus or vagus nerve, glossopharyngeal nerve, or hypoglossal nerve (most at risk with surgery at or above C3)15 34 Dysfunction of the pharyngeal plexus, which affects the motility of the visceral wall30
Dissection or retraction of the longus colli muscle	Muscle and subperiosteal bleeding; prevertebral soft tissue swelling20
Retraction	Denervation of the pharyngeal plexus35 (involving the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve)29
Excessive or prolonged retraction	Dysphagia15 25 28 29 38 39 52 Esophageal edema,25 impingement,13 ischemia,28 36 55 56 denervation,5 reperfusion injury36 Posterior pharyngeal wall edema, preventing a full epiglottic deflection30 Soft tissue fibrosis28; soft tissue swelling5 30 36 39; scar tissue formation5 19
Significant tension during lateralization of the larynx (RLN most at risk with surgery involving C3–C4 and C5–T1)	RLN injury, which can cause vocal fold paresis or paralysis42
RLN stretch injury and/or RLN compression injury from ET cuff compression	RLN palsy, which can cause vocal fold paresis or paralysis42
Use of rh-BMP-2	Early local inflammatory response to rh-BMP-2 (dose-related)48
Concurrent intraoperative traction on both the RLN and pharyngeal plexus36	RLN injury
Other aspects of operative approach
Direct esophageal injury	Impaired opening of the upper esophageal sphincter30 Localized denervation of portions of the esophagus and hypopharynx13 28 Pharyngeal wall ischemia55 56
Hemostatic or coagulopathy	Hematoma formation19 23
Operative technique
Use of instrumentation	Any mechanical irritation or impingement against the esophagus27 Differences in postoperative cervical kyphotic-lordotic deformity28
Thickness or anterior profile of anterior cervical plates and instrumentation	Irritation and inflammation13 28
Plate on the esophagus	Mass effect29
Use of graft	Graft (implant) protrusion,19 34 graft extrusion or cord compression13
Improper halo or collar positioning	Cervical hyperextension23

Abbreviations: ET, endotracheal; rhBMP-2, recombinant human bone morphogenetic protein-2; RLN, recurrent laryngeal nerve; SLN, superior laryngeal nerve.