Transmaxillary Transpterygoid Approach: A Microanatomical Study

Purpose: The Le Fort I transmaxillary approach is indicated for extradural lesions of the clivus; the lateral exposure is limited by the pterygoid plates. The authors conducted a cadaveric microanatomical study to describe a modified transmaxillary Le Fort I approach aimed at improving the lateral clival exposure through a medial and posterior antrectomy and the removal of the pterygoid plates.

Method: Six cadaveric specimens injected with latex and fixed on glutaraldehyde were used for the microscopic procedures and morphometric measurements. Using the ImageJ software the areas exposed using the standard Le Fort I transmaxillary approach (STMA) and the transmaxillary transpterygoid approach (TMTPA) were calculated and compared.

Result: The area exposed with the STMA ranged from 5.3 to 7.2 cm² (mean, 6.5 cm²; SD, 0.7 cm²; CI, 5.9 to 7.1 cm²); the area exposed with the TMTPA ranged from 10.2 to 14.8 cm² (mean, 12.9 cm²; SD, 1.8 cm²; CI, 11.5 to 14.3 cm²). The difference in the amount of area exposed with the TMTPA compared with the STMA ranged from 4.9 to 7.6 cm² (mean, 6.4 cm²; SD, 1.2 cm²; CI, 5.4 to 7.4 cm²). The percentage of the amount of additional area exposed using the TMTPA ranged from 83 to 109% (mean, 99%).

Conclusion: The TMTPA improves the lateral clival exposure, allowing access to the pterygopalatine fossa, medial infratemporal fossa and medial parapharyngeal space, and related neurovascular structures. A good exposure of the petrous and distal infratemporal carotid artery is also achieved. If compared with the STMA, the TMTPA doesn't present a significant adjunctive morbidity. Morphometric measurements and related calculations demonstrate that the clival and paraclival area exposed using the TMTPA is about twice that exposed using the STMA.