ONS Advance Access:Endoscopic Endonasal Interdural Middle Fossa Approach to the Maxillary Nerve: Anatomic Considerations and Surgical Relevance

Transcranial approaches directed towards the intracranial segment of the maxillary nerve (V2) include the use of middle fossa approaches or the Dolenc et al approach.13 These extradural approaches involve mobilization of the dura propria (middle fossa dura) from the lateral wall of the cavernous sinus and/or the periosteal layer surrounding the V2 in the middle fossa triangles outside the cavernous sinus.

Perineural tumor extension may occur with benign as well as malignant sinonasal and skull base neoplasms and can significantly alter the disease course by complicating tumor-control and survival rates, making resection of potentially infiltrated segments a desirable surgical objective.4,5 Surgical treatment including the use of open approaches in addition to adjuvant treatment is the primary treatment modality for many of these lesions.6,7

In this brief technical note, with increasing use of endoscopic endonasal surgery, we investigated the anatomy of the V2 and its specific segments with respect to the endonasal landmarks like maxillary strut. The feasibility of achieving surgical resection of these segments with preservation of the middle fossa dura endonasally using a technical modification, the endoscopic endonasal interdural middle fossa approach, was explored. The anatomic limits dictating the mobilization and resection of the V2 were also explored in relation to the critical neurovascular structures including the cavernous sinus, the paraclival carotid artery, and the Gasserian ganglion.

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