Endoscopic endonasal approach to the infraorbital nerve with nasolacrimal duct preservation.

Objectives Infraorbital nerve (ION) decompression, excision to remove intrinsic tumors, and resection with oncological margins in malignancies with perineural invasion or dissemination are usually accomplished with an open approach. The objective is to describe the surgical anatomy, technique, and indications of the endonasal endoscopic approach (EEA) to the ION with nasolacrimal duct preservation. Design Eleven sides of formalin-fixed specimens were dissected. An anterior maxillary antrostomy was performed. The length of the ION prominence within the sinus and anatomic features of the covering bone were studied. A 45-degree endoscope visualized the infraorbital prominence endonasally. An angled dissector and dural blade allowed for dissection and resection of the ION ipsilaterally and contralaterally. Results The bone features of the ION prominence allowed for ipsilateral dissection in 10 out of 11 sides. In one case with the ION surrounded by thick cortical bone, the dissection could only be started by drilling contralaterally. The 45-degree endoscope visualized 92.2% and 100% of the length of the nerve using the ipsilateral and contralateral nostrils, respectively. Ipsilaterally, 83% of its length was resected, and 96.3% was resected contralaterally. Conclusion The ION can be approached using an ipsilateral EEA with nasolacrimal duct preservation in most cases. The contralateral approach provides a wider angle to access the ION. This technique is primarily indicated in cases where the EEA can be used for tumor resection and oncological margins within the ION.