Case Report: transcavernous sinus resection of parotid carcinoma with perineural invasion to Meckel's cave and cavernous sinus.

[BACKGROUND] Adenoid cystic carcinoma (ACC) of the salivary glands is a rare but aggressive malignancy known for perineural invasion (PNI), allowing tumor spread along cranial nerves to the skull base, Meckel's cave, and cavernous sinus. Cavernous sinus involvement has traditionally been considered inoperable due to the density of neurovascular structures. Recent advancements in skull base microsurgery and anatomical landmark-guided navigation have enabled radical tumor resection in carefully selected patients.

[OBJECTIVE] To describe a tailored pretemporal extradural transcavernous skull base approach, combined with infratemporal fossa exposure, for radical resection of parotid ACC with extensive PNI into Meckel's cave and the cavernous sinus, emphasizing internal carotid artery (ICA) skeletonization, fascicular-level nerve dissection and repair, and precision bone work.

[METHODS] A 54-year-old male presented with progressive left facial paralysis (House-Brackmann grade VI), trigeminal pain (V), diplopia, and cranial nerve IV and VI palsies. MRI demonstrated a tumor extending along the mandibular nerve (V) via the foramen ovale into Meckel's cave and cavernous sinus, circumferentially encasing the cavernous ICA with patent lumen. High resolution neuroimaging confirmed perineural spread; PET-CT showed no metastasis. A modified Dolenc pretemporal extradural transcavernous approach was performed without orbitozygomatic osteotomy. Bone removal was limited to V-V triangle drilling, exposing the infratemporal fossa and Meckel's cave. ICA skeletonization was guided by the vidian canal, lingual petroclival ligament, and petrosphenoidal ligament, with intraoperative Doppler confirmation. Fascicular-level neurorrhaphy reconstructed infiltrated V fibers. Multilayer skull base reconstruction with autologous fat grafts provided watertight closure and radioprotection.

[RESULTS] Gross total resection was achieved with preserved integrity of the ICA and all cranial nerves. No new neurological deficits occurred; preexisting palsies remained stable. Pathology confirmed ACC with extensive PNI; immunohistochemistry was positive for Hematoxylin and eosin, B-catenin, CK-7, and S100. Postoperative MRI verified complete cavernous sinus tumor removal. The patient recovered well and was referred for adjuvant stereotactic radiotherapy.

[CONCLUSION] This case demonstrates that even extensive cavernous sinus invasion by parotid ACC can be safely addressed with curative intent through precision-based microsurgery. A modified Dolenc approach with limited bone work and infratemporal extension enables maximal resection while preserving function. Strategic reconstruction optimizes safety for adjuvant radiation. This report adds to the growing evidence supporting aggressive yet function-preserving surgical management of malignant skull base tumors in multidisciplinary oncology programs.