Radioanatomic Study of the Greater Palatine Canal Relevant to Endoscopic Endonasal Surgical Landmarks.

Objective A radioanatomic study of surgically relevant variations in the greater palatine canal (GPC) on computed tomography (CT) was performed to determine susceptibility during endoscopic endonasal procedures. Study Design Blinded radioanatomic analysis. Setting Tertiary university hospital. Subjects and Methods Fifty consecutive paranasal CT scans (100 sides) were analyzed. Measurements were standardized to landmarks such as the inferior turbinate (IT) and floor of the nasal cavity (FNC) to assess variability and vulnerability of the nerve. Measurements included (1) incidence of maxillary sinus pneumatization posterior to the GPC, (2) distance from the posterior wall of the maxillary sinus to the GPC at the IT and FNC, (3) width of bone containing the GPC, (4) incidence of medial GPC dehiscence, and (5) angle of the GPC extending from the IT to FNC. Results Ninety-one percent of maxillary sinuses were pneumatized posterior to the GPC. The distance from the posterior wall of the maxillary sinus to the GPC was 2.8 ± 1.7 mm (range, -2.3 to 5.9) at the posterior attachment of the IT and 4.1 ± 3.1 mm (range, -6.3 to 11.9) at the FNC. The width of bone containing the GPC was 3.3 ± 1.3 mm (range, 1-8.9), and the medial bony GPC was dehiscent in 38% of cases. In the sagittal plane, the angle of the GPC between the IT and the FNC was 31.9 ± 6.9 degrees (range, 10.8-45). Conclusion The GPC has considerable anatomic variability relative to important surgical landmarks in endoscopic procedures. Preoperative review of CTs to assess vulnerability may prevent postoperative complications.