Pterygopalatine fossa infiltration through the greater palatine foramen: Where to bend the needle

Objective. In the literature, there has been controversy regarding the length of the greater palatine canal. If the pterygopalatine fossa is infiltrated in an attempt to reduce bleeding during sinus surgery, this information is important to be able to place local anesthetic with maximal effect and the least likelihood of complications. Study Design. The authors conducted a prospective cadaver-based study using high-definition computed tomography (CT) scans. Methods: Twenty-two cadaver heads were CT scanned and the greater palatine canal length, pterygopalatine fossa height, and thickness of the soft tissue in the roof of the mouth were measured on parasagittal images using the CT scanner workstation. Results. The mean length of the greater palatine canal was 18.5 mm (95% confidence interval [CI] = 17.9-19.1) and the mean height of the pterygopalatine fossa was 21.6 mm (95% CI = 20.7-22.5). The mean thickness of the soft tissue in the roof of the mouth overlying the foramen of the greater palatine canal was 6.9 mm (95% CI = 6.2-7.6). Conclusion: To perform an effective infiltration of the pterygopalatine fossa, the needle should be bent at 25 mm from the tip at an angle of 45 degrees.