Transorbital drillout to the cavernous sinus: an approach for squamous cell carcinoma with perineural spread. Illustrative cases

BACKGROUND: This study describes a transorbital apical approach to the cavernous sinus, where the greater wing of sphenoid (GWS) and superior orbital fissure (SOF) are drilled out to access the interdural incision zone and lateral wall of the cavernous sinus. OBSERVATIONS: This was a retrospective series of 3 patients with periocular squamous cell carcinoma (SCC) and radiological evidence of perineural spread to the cavernous sinus. Following an orbital exenteration, the GWS was drilled to reach the lateral border of the SOF. The meningo-orbital band, a periosteal transition between the frontotemporal basal dura and periorbita, was incised to enter the lateral wall of the cavernous sinus. The relevant cranial nerves were biopsied to provide an accurate zonal classification of disease. LESSONS: The transorbital apical approach via the SOF provides a corridor of access to the cranial nerves within the lateral wall of the cavernous sinus. This technique was successfully performed on 3 patients with periocular SCC. One case had radiological evidence of intracavernous oculomotor nerve involvement, 1 patient demonstrated nasociliary nerve enlargement at the SOF, and another had frontal nerve involvement extending into the cavernous sinus. Cerebrospinal fluid leak occurred in 1 case addressed with fat packing and fascial closure.