Anatomical and Radiological Parameters of the Sphenoid Sinus among Egyptians and its Impact on Sellar Region Surgery

Background: Pneumatization of the sphenoid sinus provides a dilating natural cavity through which wide areas of the cranial base may be accessed. Careful examination of various pneumatized extensions of the sphenoid sinus may facilitate extended approaches directed through the sinus to the perisellar pathologies. Objectives: to provide anatomical information among Egyptians about the location of the sphenoid sinus inside and outside the sphenoid bone and how to use extended pneumatization as natural trajectories to various targets at the skull base. Material and Methods: This study was conducted on twenty five adult dried hemi skulls. Different sagittal, coronal and axial cuts were carried out to evaluate the pattern and extent of pneumatization through the sphenoid bone in various directions, bulges and dehiscence of relevant neurovascular structures. The morphometry of the vidian canal and foramen rotundum was analyzed. The results were correlated with the outcomes from CT and MRI images of three hundred sixty four patients who were retrospectively evaluated at a period between 2010 and 2013. Results: In the anatomical twenty five specimens, no conchal pattern, three (12%) were presellar type and twenty two (88%) were sellar type. The pneumatization within twenty two sellar sinuses (88%) showed ninespecimens (36%) of sphenoid body type, seven specimens (28%) of lateral type, three specimens (12%) had clival recesses, three specimens (12%) with lesser wing type (Anterior clinoid process type). On the other hand, among the radiologically-examined three hundred sixty four cases, there were six cases(1.6%) showing conchalpneumatization, forty six cases (12.6%) with presellar pneumatization and three hundred twelve cases (86%) showing sellarpneumatization. The sellar pattern was reclassified into six types; sphenoid body type was found in seventy three cases (20%). the lateral type of extension was found in forty six cases (12.6%). Twenty seven patients (7.4%) presented with clival type sinuses. Superior wall, optico-carotid and tuberculum recess (Lesser wing type), was found in seven cases (2%). The sphenoid sinus with anterior recess (anterior type), was found in fifty six cases (15%). Combined type of pneumatization existed in the same case, were found in one hundred eighty two cases (50%). Conclusion: The full preoperative anatomical information of each patient going to extended transsphenoidal surgery is important to assess different types of extension of sphenoid sinus pneumatization, areas of bony dehiscence and areas of critical septal terminations and subsequently avoid injury of the nearby neurovascular structures and reduce the possibility of CSF leakage.