6 Transfrontal Approach

10.1055/b-0039-172568

6 Transfrontal Approach

Francesco Belotti, Marco Ravanelli, Marco Angelo Cocchi, Vittorio Rampinelli, Francesco Doglietto

In very selected cases, the frontal sinus can serve as a corridor toward lesions with isolated involvement of the posterior frontal plate, ¹ – ⁴ which is the most anterior subunit of the midline anterior skull base. They are mostly included in the group of nasofrontal dysembriogenic lesions, which entails dermoid sinuses, dermoid cysts, nasal gliomas, and meningoencephaloceles. ² ^, ⁵ – ⁷ Although based on limited case series, the endoscopic approach provides favorable results with minimal morbidity in adequately selected cases. Given the tendency of these malformations to grow toward the external nose, a combined endoscopic rhinoplasty technique can also be indicated in selected cases. ² On the other hand, the transfrontal approach can be employed to manage selected benign tumors or tumorlike lesions of the frontal sinus and adjacent skull base (e.g., osteomas, inverted papillomas, glomangiopericytomas, and mucocele) that show no far-lateral extension and no involvement of the anterior frontal plate. ¹ ^, ³ ^, ⁴ ^, ⁸

The transfrontal endoscopic corridor, which requires a wide Draf type III frontal sinusotomy, is bounded by the nasal bones anteriorly, nasal septum and cribriform plate posteriorly, and orbital cavity bilaterally. This surgical route is quite challenging due to several reasons: (1) it is oriented in a caudal-to-cranial fashion and shows very narrow anteroposterior and lateral–lateral diameters that hamper surgical maneuvers and facilitate the “sword-fighting” phenomenon during surgery; (2) the boundaries of the corridors must be accurately preserved to avoid injuring the midline anterior skull base, skin of the nose, and anterior orbital content; (3) the reconstruction of the skull base can be made difficult by the three-dimensional geometry of the defect and limited maneuverability of instruments; (4) in cases requiring a transdural resection, attention must be paid to not damage the superior sagittal sinus, bridging veins, and orbitofrontal and frontopolar arteries.

By virtue of its difficulty and rarity of adequate indications, the transfrontal endoscopic approach might arouse limited interest in the reader. However, this approach allows to face an area that is infrequently thoroughly explored with other endoscopic skull base approaches, although its anatomy should be mastered to approach far-anterior lesions of the midline skull base. In fact, secondary involvement of this anterior region from lesions that originate from adjacent skull base areas (i.e., cribriform plate and fovea ethmoidalis/ethmoidal roof) is quite frequent.