2026 Proffered Presentations
S139: ENDOSCOPIC SKULL BASE ROUTES TO THE HIPPOCAMPUS IN CHILDREN WITH PHARMACORESISTANT EPILEPSY: CT/MRI MORPHOMETRIC EVALUATION OF THE MAXILLARY SINUS
Rakhmon Egamberdiev, MD1; Thibault Passeri, MD1; Gianluca Fabozzi, MD1; Maria Karampouga, MD1; Garret Choby, MD2; Eric Wang, MD2; Georgios Zenonos, MD1; Carl Snyderman, MD2; Paul Gardner, MD1; 1Department of Neurological Surgery, University of Pittsburgh Medical School (UPMC), Pittsburgh, USA; 2Department of Otolaryngology, University of Pittsburgh Medical School (UPMC), Pittsburgh, USA
Introduction: Amygdalohippocampectomy remains a key option for epilepsy treatment in children, yet the choice of surgical corridor may be limited by age-related anatomical development. Transmaxillary and endoscopic endonasal approaches offer minimally invasive access to the hippocampus, but the impact of the size and pneumatization of the pediatric maxillary sinus on their feasibility is unknown. This study aimed to define age-based eligibility for these approaches by analyzing maxillary sinus development on pediatric CT and MRI.
Methods: A retrospective radiological morphometric study was performed on 12 pediatric patients and 1 adult patient (ages 3–19 years) who had undergone transcranial epilepsy surgery with available preoperative CT and/or MRI scans. Bilateral maxillary sinus dimensions—including height, width, and anteroposterior length—were measured using multiplanar reconstruction in axial, coronal, and sagittal planes. Additional parameters, such as maxillary sinus operative aperture sizes and maxilla–skull base relationships, were recorded. Age at the time of surgery was correlated with morphometric parameters to identify developmental thresholds for potential endoscopic endonasal and transmaxillary access to the hippocampus.
Results: Twenty-six sides were analyzed. Maxillary sinus dimensions demonstrated progressive, age-dependent increases. In early childhood, the maxillary sinus and its aperture typically exhibited a slit-shaped configuration; with increasing age, both evolved toward a quadrangular shape. Based on this morphology, we deemed slit-shaped sinuses not feasible for endonasal/transmaxillary surgery, whereas quadrangular sinuses provided feasible working corridors. Dimensions for children <10 years (mean age 6.8 years): mean sinus height 19.1 mm (range 11.7–26.2), width 22.4 mm (10.1–35.5), length 24.0 mm (range 18.5–28.4), and mean aperture width 20.2 mm (range 14.3–26.1) At this age, sinus dimensions were generally insufficient for consistent exposure, though 2 cases above 7–8 years showed borderline feasibility. For children 10–14 years (mean age 12.3 years): sinus height increased to 23.3 mm (20.3–27.6), width 21.8 mm (18.8–24.1), and length 32.0 mm (range 28.6–33.2), with a mean aperture width of 25.9 mm (range 22.7–28.4). In this group, access became increasingly reliable, though anatomical variability remained. Adolescents ≥15 years (mean age 16.6 years): values approached adult morphology, with mean height 31.7 mm (27.4–36.1), width 31.2 mm (27.2–36.3), and length 37.8 mm (range 32.2–45.0), and mean aperture width 31.0 mm (range 28.7–33.9). In this group, endonasal and transmaxillary approaches consistently provided sufficient working corridors. The width of the maxillary sinus remained relatively constant (~26–30 mm), suggesting that lateral expansion is less influenced by age compared to vertical and anteroposterior growth.
Conclusion: Maxillary sinus development is a critical determinant of surgical access to the middle fossa and hippocampus in children through endoscopic transmaxillary route. Transmaxillary and endoscopic endonasal approaches appear anatomically constrained in patients younger than 6 years, variably feasible between 6–8 years, and achieve reliable exposure from age 9 onward. These findings provide practical, age-based guidelines to assist neurosurgeons in selecting minimally invasive skull base routes in pediatric amygdalo-hippocampectomy.
FIGURES
Figure 1. Maxillary sinus dimensions by age.
Figure 2. Orbital floor height in relation to age.
Figure 3. Distances from reference points to critical anatomical landmarks (V2, V3, temporal horn, and lateral geniculate body).
