The Occipital Recess of the Sphenoidal Sinus-A Novel Anatomical Possibility.

There are reported here multiple rare anatomical variants of the sphenoidal sinus found in a 53-year-old male. The sinus exhibited uncommon features, including a prominent occipital recess extending bilaterally into the basilar part of the occipital bone. A narrow posterior isthmus connected the main chamber to 2 recesses: a superior postsellar recess pneumatising the dorsum sellae, and a postero-inferior occipital recess. The latter extended into the right basilar occipital bone, closely associated with the right hypoglossal canal and coursing alongside the right internal carotid artery. In addition, the sphenoidal sinus had a maxillary recess projecting above the pterygopalatine fossa and joining the right maxillary sinus and bilateral pterygoid recesses. Notably, the left vidian canal was situated superior to the pterygoid recess with no pneumatic space between it and the foramen rotundum, unlike the right side. These anatomical variants are clinically significant due to their proximity to vital neurovascular structures, increasing surgical risks. Partial ossification of the falx cerebri was also identified, potentially complicating neurosurgical procedures.