Anatomic Landmarks and Morphometric Measurements for Accurate Localization of the Sphenopalatine Ganglion via the Transnasal and Infrazygomatic Approaches: A Cadaveric Study

Objective: Sphenopalatine ganglion (SPG) block is used for a variety of craniofacial pain syndromes either through the transnasal route or via the infrazygomatic approach. Intraoperative imaging can identify the pterygopalatine fossa (PPF) but not the exact position of the SPG. Accurate localization of the SPG requires knowledge of the relevant anatomical landmarks. Materials and methods: Thirty mid sagittal head and neck cadaveric sections were studied and the morphometric data was collected to facilitate correct SPG localization via trans-nasal approach and infrazygomatic approach. Results: The sphenopalatine foramen (SPF) was located at an average distance of 55 mm from the anterior nasal spine at a mean angle of 22°. It was at or just superior to the midpoint of a line joining the skull base and the hard palate. The SPG was located 4 mm posterior and 4.7 mm lateral to the SPF at a mean distance of 6.3 mm from the SPF at an inclination of about 50° in both the sagittal and coronal planes. In the infrazygomatic approach, the SPG was between 4.5 and 6.3 cm from the skin and an angle of about 7° posterior and inferior. Conclusion: These morphometric measurements will be of help to the clinician for accurate electrode or needle placement for SPG block and in avoiding complications related to inaccurate needle placement.