Frontal Sinus Window for Minimally Invasive Access to the Frontal Sinus and Anterior Skull Base

Background: Minimally invasive approaches to the skull base continue to evolve. Although endoscopic endonasal approaches can be used to access the anterior skull base and frontal sinus, lesions in the lateral frontal sinus may be inaccessible. Additionally, lesions located in the lateral confines of supraorbital ethmoid cells may be difficult to reach via traditional endonasal approaches. In these situations, an alternative approach using a frontal sinus anterior table window may provide the most direct, least invasive access.

Objectives: Describe the technique and our experience using an anterior table frontal sinus window for minimally invasive access to lateral frontal sinus and anterior skull base lesions.

Methods: The anterior table of the frontal sinus is exposed using either a brow incision or blepharoplasty type incision. Dissection is carried down to the periosteum preserving the supraorbital and supratrochlear neurovascular bundles. Using a drill, a 1-cm oval window is created in the anterior table of the frontal sinus. This window can be enlarged as necessary depending on the dissection required. Then, two- to three-handed endoscopic techniques can be implemented to address lesions in the lateral frontal sinus or anterior skull base.

Results: We used this technique to address lesions located in the lateral frontal sinus including benign tumors and encephaloceles. We also repaired skull base defects in supraorbital ethmoid cells using this approach. In each case, we were able to preserve normal sinonasal physiology based on clinical examination and postoperative imaging. The location of the window was different in each patient to provide the most direct access to the lesion and address the lesion with the smallest possible window size. To date, we have not had any permanent complications or cosmesis complaints except transient forehead numbness in one patient.

Conclusions: The frontal sinus window can provide access to lesions in the lateral frontal sinus and anterior skull base, including supraorbital ethmoid cells. In select cases, this approach may offer the most direct route to the lesion of interest with the least morbidity. Strategically placed incisions minimize visible scars.