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Page 2 of 11 Azab et al. Mini-invasive Surg 2020;4:88 I http://dx.doi.org/10.20517/2574-1225.2020.75

INTRODUCTION
Anterior skull base meningiomas are benign, dural-based tumors that originate from the tuberculum sellae,
planum sphenoidale or olfactory groove which includes the lamina cribrosa and frontoethmoidal suture.
[1-3]
Olfactory groove meningiomas account for 8%-13% of all intracranial meningiomas , while tuberculum
sellae and planum sphenoidale meningiomas constitute around 10%-15% of meningiomas and often present
[4,5]
with visual disturbance due to compression of the optic nerves and chiasm [Figure 1].
From a pathoanatomical point of view, tuberculum sellae meningiomas are in close anatomical proximity
to the optic nerves, optic chiasm, internal carotid artery, and anterior cerebral artery, as well as the
hypothalamus, infundibulum and pituitary gland [Figure 2]. In comparison to planum sphenoidale
meningiomas, true tuberculum sellae meningiomas are centered on the tuberculum sellae and grow
[6]
posterosuperiorly displacing the optic nerves superolaterally [Figure 3]. Furthermore, tumor extension
into one or both optic canals as well as vascular encasement can take place in many cases and adds to the
technical difficulty of resecting these tumors [Figure 4]. On the other hand, olfactory groove meningiomas
are in close apposition to the olfactory nerves and tend to infiltrate the cribriform plate, invade the
ethmoid and sphenoid sinuses, and engulf the anterior clinoid process as well as the vasculature in their
vicinity [1,3,7,8] .

Surgical excision is the main treatment modality for these tumors and should ideally aim at complete
[9]
removal of the tumor as well as the dural tail and invaded bone , obviously not an easily achievable or even
impossible task when it comes to meningiomas of the skull base, owing to the nature of the anatomical
environment surrounding these tumors. Subtotal resection followed by radiation therapy may therefore
be an acceptable option in some cases . Especially for tuberculum sellae and planum sphenoidale
[10]
meningiomas, surgical resection results in decompression of the optic nerves and chiasm and therefore
prevents further visual deterioration and may reverse neural damage in some cases .
[10]
Currently, minimally invasive approaches for surgical excision of anterior skull base meningiomas include
the endoscopic endonasal approach [11-14] and the endoscope-assisted or endoscope-controlled supraorbital
keyhole eyebrow approach [7,15-19] . In this article, the endoscope-assisted or endoscope-controlled
supraorbital keyhole eyebrow approaches for anterior cranial base meningiomas will be briefly elaborated
upon.

SHIFT TOWARDS MINIMALLY INVASIVE APPROACHES FOR ANTERIOR SKULL BASE
MENINGIOMAS
Over several decades, a multitude of traditional transcranial approaches have been developed and
effectively used for resection of anterior skull base meningiomas. These approaches include the pterional,
bifrontal, extended bifrontal, transbasal, orbitozygomatic, and interhemispheric approaches [2,20-26] .
Notwithstanding, morbidities related to brain retraction, superior sagittal sinus transection, frontal sinus
transgression, optic nerve or chiasm manipulation and wound healing problems [27,28] led to a quest for less
invasive alternatives.

Paving the way for the evolution of minimally invasive neurosurgery, advances in the fields of surgical
technology, microsurgery, neuroradiology and neuroendoscopy have orchestrated the development of an
array of innovative and less traumatizing solutions geared at treating a large spectrum of brain and skull
base disorders. Along with this rising tide, novel surgical approaches were developed to treat various
pathologies of the anterior skull base including meningiomas originating therein. Probably having more
impact than others, advances in endoscopic technology have significantly contributed to the development
and refinement of these approaches as they are practiced nowadays. Undeniably, minimally invasive