Bilateral olfactory groove meningioma surgery approach

• Cognitive, affective and behavioral functioning in patients with olfactory groove meningiomas: a systematic review
• Single-stage versus two-stage resection for large anterior midline skull base meningiomas with bihemispheric peritumoral edema
• Giant Olfactory Groove Meningiomas: A Case Series Demonstrating the Surgical Management and Functional Outcomes
• Is Unilateral Extended Pterional Craniotomy Adequate Instead of Bicoronal (Bifrontal) Craniotomy in Large or Giant Olfactory Groove Meningiomas?
• Giant solitary fibrous tumor of the olfactory groove. An unusual simulator in an unusual location
• Extended Unifrontal craniotomy for midline anterior cranial fossa meningiomas: A better shot at preservation of neurovascular structures
• Widening the Operative Corridor-Evaluating the Transcortical Approach to Giant Falcine Meningiomas
• Olfactory groove meningiomas: supraorbital keyhole versus orbitofrontal, frontotemporal, or bifrontal approaches

Surgical removal is often performed through the bifrontal, unilateral subfrontal (frontolateral), or pterional approach.

Bi-coronal subfrontal approach appears to be an excellent technique for Olfactory groove Meningioma removal as practiced by most neurosurgeons. Nevertheless, it is not mandatory to carry out orbital osteotomy to acquire optimal surgical outcome as is advocated by some authors ¹⁾

Approached via a bifrontal craniotomy (preserving the periosteum to cover the frontal sinus and floor of the frontal fossa at the end of the case). Small tumors may be approached via unilateral craniotomy on the side with the most tumor.

For large tumors, a external lumbar cerebrospinal fluid drainage will help with brain relaxation and the head is rotated 20° to one side to facilitate dissection of the anterior cerebral arteries and optic nerve while preserving visualization of both sides of the tumor involvement.

The neck is slightly extended. The dura is opened low, and the superior sagittal sinus is ligated and divided at this location. Amputation of the frontal pole should be done if necessary to avoid excessive retraction. Vascular feeding arteries come through the floor of the frontal fossa in the midline. Initially, the anterior tumor capsule is opened and the tumor debulked from within, heading towards the floor of the frontal fossa to interrupt the blood supply. The posterior capsule of the tumor is dissected carefully as this portion of the tumor may encase branches of the anterior cerebral artery, and/or optic nerves and chiasm. A large tumor with suprasellar extension usually displaces the optic nerve and chiasm inferiorly.

If necessary, the frontopolar branch and other small branches may be sacrificed without a problem.

Periosteum is laid over the floor of the frontal fossa. To hold it in place, one may attempt to suture it to the adjacent dura with a couple of retaining sutures, alternatively, a small titanium plate (e.g. “dogbone”) can be placed over the flap, and screws are placed into the bone of the floor of the frontal fossa (both methods are challenging). Post-op risks include CSF leak through the ethmoid sinuses.

The neurovascular structures come into view late, after a major part of the tumor has been removed. The superior sagittal sinus should be divided, compromising venous drainage from the frontal lobes and thus contributing to brain edema ^{2) 3)}.

Anterior interhemispheric approach

Transsinusal frontal approach