Expanding the Limits to the Infratemporal Fossa and Parapharyngeal Space through the Endoscopic Nasofrontal Trephination: A Quantitative Cadaveric Study

Objective: The infratemporal fossa (ITF) presents a significant challenge for surgical access due to its deep and complex anatomy. The endoscopic endonasal approach (EEA) to the ITF has improved the management of select sinonasal and skull base lesions within this region. Several endoscopic approaches have been described to expand access and enhance both visualization and instrumentation to the ITF. These include the endoscopic-assisted sublabial anterior maxillotomy (anteroposterior access), or the contralateral endonasal approach through septotomy (lateral access). This study aims to assess the feasibility, anatomical aspects, and limitations of the nasofrontal trephination technique, unilaterally or bilaterally, as a complementary corridor to improve surgical access to the ITF.

Methods: Endoscopic endonasal and nasofrontal trephination approaches were performed bilaterally in 10 cadavers (20 sides). Four different approaches to the ITF were evaluated including ipsilateral endonasal, contralateral endonasal through septotomy, ipsilateral nasofrontal trephination, and contralateral nasofrontal trephination through septotomy. An initial ethmoidectomy and medial maxillectomy were performed by the removal of the posterior wall of the antrum and its periosteum; thus, exposing the pterygopalatine and infratemporal fossae. The superficial head of the medial pterygoid muscle was dissected, and the maxillary artery and its branches were identified. A 2 cm septal window was created after raising mucosal flaps on both sides. For the trephination, a nasofrontal incision was carried down to the bone exposing the meeting point of the frontal, nasal, and frontal process of the maxillary bones, which is then drilled out. A subsequent Draf 2a connects the nasal cavity with the nasofrontal window. An endoscopic-assisted sublabial 1.5 × 1.5 cm maxillotomy was lastly performed. Quantitate analysis of the approaches included the area of exposure, angle of approach, and maximum reach distances.

Results: Area of exposure offered by the ipsilateral EEA (493 ± 171 cm²) was significantly smaller than the area exposed by the contralateral EEA, anterior maxillotomy, ipsilateral nasofrontal trephination, and contralateral nasofrontal trephination (689 ± 134 cm², 778 ± 168 cm², 789 ± 119 cm², and 914 ± 141 cm², respectively; p < 0.05). The frontal trephination afforded a significant increase in the angle of approach to the target, offering greater freedom of movement among instruments (29.83 ± 3.65 degrees; p < 0.05). The maximum reach increased significantly only in the lateral and inferior extent (15.44 and 36.41 mm, respectively).

Conclusion: The addition of the nasofrontal trephination portal as a complementary corridor to the endonasal route provides superior access to deep areas of the ITF. The lateral and inferior reach within the ITF were significantly increased using either an ipsilateral or contralateral nasofrontal trephination. This study provides new insights into the anatomical nuances and potential benefits of a dual-port ITF resection, albeit, within the limitations of a cadaveric preclinical study.