Hypoplasia of Bilateral Sphenoid Sinuses: Implications in Transsphenoidal Adenohypophysectomy

Introduction: Hypoplasia and agenesis of the sphenoid sinuses is a rarely observed anatomic variation. Prior studies have examined variations in sphenoid pneumatization patterns; less is known regarding hypoplasia and agenesis of the sphenoid sinuses.

Objective: Pneumatization and size of the sphenoid sinuses is of clinical importance in patients presenting with a pituitary tumor. Hypoplasia of the sphenoid sinus can increase difficulty of tumor exposure as well as increase risks of complications during transsphenoidal adenohypophysectomy. We report a case of a severely hypoplastic sphenoid sinus and review the clinical and operative implications.

Case Presentation: A 59-year old female patient presented with a 6.3-cm pituitary mass and marked hypoplasia of the bilateral sphenoid sinuses. Transsphenoidal adenohypophysectomy was performed. The extremely hypoplastic nature of the sphenoid caused the anterior wall of the sphenoid to be continuous with the sella, limiting operative exposure due to proximity to the cavernous carotid arteries and optic nerves.

Discussion: Hypoplasia of the paranasal sinuses is usually incidental findings on imaging. Agenesis of the sphenoid sinuses is rarer, with only about a dozen previously reported cases of bilateral sphenoid sinus agenesis. Though rare, this anatomic variation can have significant implications for skull base surgery, particularly when this may limit exposure or alter the location of critical structures.

Conclusion: Hypoplasia or agenesis of the sphenoid sinus, though rare, is important to recognize in patients with pituitary lesions as the operative exposure may carry higher risks. In these cases, careful review of the altered anatomy and image guidance is of utmost importance.