Endoscopic Windows for Increased Visualization in Endoscopic Skull Base Surgery

Objectives: To quantify progressive nasopharyngeal and posterior maxillary wall exposure using a zero-degree endoscope through the addition of posterior septal window and Denker’s procedure in endoscopic skull base surgery.

Design: Anatomic cadaver study.

Setting: Anatomy laboratory.

Participants: Six dissections in latex injected human cadaver specimens.

Main Outcome Measures: Nasopharyngeal and maxillary sinus mucosal exposure were quantified with measurements made with a 0-degree endoscope from the head of both the inferior (IT) and middle turbinates (MT) with and without a posterior septal window or anterior “Denker’s” maxillary window.

Results: The average exposure of nasopharyngeal mucosa using a 0-degree endoscope was 2.1 ± 1.0 cm² from the IT and 2.8 ± 1.0 cm² from the MT. The creation of an ~1 cm × 2 cm posterior septal window led to a statistically significant increase in nasopharyngeal exposure to 4.9 ± 2.3 cm² from the IT and 8.9 ± 4.7 cm² from the MT (two-tailed t-test, p < 0.05). After creation of a medial Denker’s maxillectomy, the extent of lateral exposure of the posterior maxillary sinus was measured from the medial maxillary sinus wall using a 0-degree endoscope and found to be 1.3 ± 0.2 cm at the IT and 2.2 ± 0.4cm at the MT. Addition of Denker’s procedure resulted in a significant increase in lateral exposure to 3.3 ± 0.6 cm and 4.1 ± 0.1 at the IT and MT, respectively (two-tailed t-test, p < 0.05).

Conclusions: The posterior septal window results in a significant increase in area of nasopharyngeal exposure, and Denker’s procedure a significant increase in lateral exposure of the posterior maxillary wall in skull base surgery with a 0-degree endoscope. When working with a two-surgeon four-handed technique, 0-degree visualization gives the team the most direct operating corridor, and the majority of our instruments are best designed for 0-degree exposures. These endoscopic “windows” provide important tools to the endoscopic skull base surgeon for maximizing targeted exposure to the skull base while minimizing surgical morbidity.

No conflict of interest has been declared by the author(s).