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Page 2 of 15 Cossu et al. Mini-invasive Surg 2020;4:60 I http://dx.doi.org/10.20517/2574-1225.2020.52

Keywords: Cavernous sinus, meningioma, skull base, surgery, endoscopy, radiosurgery, radiotherapy

INTRODUCTION
Meningiomas account for one third of primary intracranial tumors with an incidence of 3-8 per 100,000
[2]
[1]
persons . They represent more than 40% of lesions involving the cavernous sinus (CS) . CS meningiomas
originate or invade the parasellar space: they may start primarily within the CS or it may be involved
secondarily in clinoidal or other sphenoid wing meningiomas, in addition to those arising from the
tuberculum sellae or spheno-petro-clival region. CS meningiomas are deeply located near critical
neurovascular structures such as the optic pathways, the hypothalamo-hypophyseal axis, the internal
carotid artery and its branches, and the oculomotor and trigeminal nerves. They may further extend into
the supra and latero-sellar spaces, orbital apex and optic canal, sphenoid ridge, middle temporal fossa, and
petroclival angle. The CS region, due to its complex anatomy and its particular position in the antero-lateral
skull base, has always been a challenging area of treatment for neurosurgeons.

As with the great majority of intracranial meningiomas, CS meningiomas are WHO grade I tumors with a
very slow growing rate. Their surgical treatment may result in significant neurological morbidity and even
death. For this reason, the management of these patients should be multidisciplinary discussed according
to the size, extension, clinical presentation, and evolutive pattern to grant the patients the longest survival
possible with the lowest cranial nerve morbidity.

[3]
Small and asymptomatic meningiomas are often managed conservatively . In general, 15% of patients have
[4,5]
neurological deficits at presentation . Ophthalmoplegia, secondary to tumor growth or as a complication
of treatment, can represent a serious issue that strongly impairs the quality of life of these patients, affecting
their self-image and their private and professional life. Thus, a balance between the different therapeutic
options should be found for symptomatic CS meningiomas. A complete preoperative endocrinological
assessment and an ophthalmological evaluation should be performed for every patient with visual
complaints and/or radiological compression of the optic apparatus.

Symptomatic meningiomas enclosed in the cavernous sinus are offered up front radiosurgery or stereotactic
fractionated modality. Tumors presenting a lateral extension should be addressed through a transcranial
approach for the resection of the extracavernous portion. In surgical series, recurrences and progression
free-survival rates range from 6% to 25% and from 4.5% to 65%, respectively, while the mortality rate
[6-8]
varies between 2% and 7% and the morbidity from 10% to 65% . Thus, the results in terms of complete
tumor removal, preservation of neurological functions, and quality of life do not always correspond to
[9]
the expectations. Saberi et al. showed that the most important variable influencing the surgical outcome
was the grade of encasement of nerves and vessels. The histological type, extent of dural attachment, and
relationship and encasement with neurovascular structures should thus be carefully considered for the
optimal management of CS meningiomas.

With CS meningiomas presenting a medial extension into the sphenoid sinus or extending into the
antero-inferior portion of the CS, an endonasal approach can be performed as the tumor itself may
create a safe space between the anterior dura and the internal carotid artery (ICA). Over the last few
decades, endoscopic endonasalapproaches have remarkably developed with the development of extended
approaches [10-14] . Through the transnasal route, it is possible to safely remove the tumor with a partial
debulking, to decompress the optic canal or to perform a tissue biopsy when the diagnosis is not clear,
particularly when another histological nature is suspected (lymphoma, granuloma, ectopic pituitary
adenoma, neurofibroma, cavernous hemangioma, etc.) [15-19] . The goals of endoscopic endonasal procedures