Mapping surgical coordinates of the sphenopalatine foramen: surgical navigation study.

OBJECTIVES To identify measurements that may help intra-operative localisation of the sphenopalatine foramen. DESIGN The study used three-dimensional surgical navigation software to study radiological anatomy, in order to define the distances and angulations between identifiable bony landmarks and the sphenopalatine foramen. RESULTS The distance from the anterior nasal spine to the sphenopalatine foramen was 59 mm (+/-4 mm; inter-observer variation = 0.866; intra-observer variation = 0.822). The distance from the piriform aperture to the sphenopalatine foramen was 48 mm (+/-4 mm; inter-observer variation = 0.828; intra-observer variation = 0.779). The angle of elevation from the nasal floor to the sphenopalatine foramen was 22 degrees (+/-3 degrees; inter-observer variation = 0.441; intra-observer variation = 0.499). CONCLUSIONS The sphenopalatine foramen is consistently identifiable on three-dimensional, reconstructed computed tomography scans. Repeatable measurements were obtained. The centre point of the foramen lies 59 mm from the anterior nasal spine at 22 degrees elevation above the plane of the hard palate and 48 mm from the piriform aperture. We discuss how these data could be used to facilitate intra-operative location of the sphenopalatine foramen in difficult cases.