Anatomical Considerations for Endoscopic Endonasal Skull Base Surgery in Pediatric Patients

Objectives/Hypothesis: Pediatric skull base surgery is limited by several boney sinonasal landmarks that must be overcome prior to tumor dissection. When approaching a sellar or parasellar tumor, the piriform aperture, sphenoid sinus pneumatization, and intercarotid distances are areas of potential limitation. Quantitative pediatric anatomical measurements relevant to skull base approaches are lacking. Our goal was to use radio-anatomic analysis of computed tomography scans to determine anatomical limitations for trans-sphenoidal approaches in pediatric skull base surgery. Study Design: A radio-anatomic cross-sectional survey. Methods: Measurements included the diameter of the piriform aperture, posterior extent of sphenoid sinus pneumatization, and intercarotid distances on fine-cut, age-stratified maxillofacial scans. Fifty pediatric (<18 years of age) and 10 adult patients were equally subdivided into seven age groups and compared to determine age-related differences in sphenoid sinus pneumatization, skull base thicknesses, and intercarotid distances. Results: Piriform aperture width was significantly greater in adults than in patients under age 7 years (P <.002). Three fourths of the planum and sellar face and one half of the sellar floor were pneumatized by ages 6 to 7 years. Superior clival pneumatization was not evident until 12 years of age. Clival intercarotid distances were not different among groups. Drilling distances for trans-planar, trans-sellar, and trans-clival approaches are described. Conclusions: Several potential anatomic limits must be considered in pediatric skull base surgery, and these vary according to age. Piriform aperture is likely a limit only in the youngest patients (under 2 years). Sphenoid pneumatization to the planum and sella start at 3 years and complete by age 10 years. Clival intercarotid distances do not change significantly and are not prohibitively narrow in any age group.