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Avery et al. Mini-invasive Surg 2021;5:17 https://dx.doi.org/10.20517/2574-1225.2021.05 Page 13 of 18

Figure 7. A 68-year-old female presented with progressive periorbital headaches with preserved olfaction. (Top Row) Pre-operative
imaging demonstrates an olfactory groove meningioma extending posteriorly to the anterior portion of the planum sphenoidale. The
lateral extent of the tumor is confined within the medial aspects of the orbits bilaterally. This tumor is therefore amenable to an
endoscopic endonasal transcribriform approach, however, to preserve olfaction we elected to approach this tumor through a left
supraorbital eyebrow craniotomy. (Bottom Row) Post-operative imaging demonstrates gross total removal of the meningioma. Top
right image shows a post-operative CT scan demonstrating the size of the supraorbital craniotomy. The endoscopic was used to ensure
removal of tumor within the depths of the olfactory groove. Axial FLAIR imaging demonstrates no retraction injury to the left frontal
lobe. Olfaction was preserved. An endoscopic endonasal trasnscribrifom approach would have guaranteed loss of olfaction and
therefore is not the optimal approach.

If there is encasement of the ACAs, early identification posteriorly provides proximal control, and as with
tuberculum sellae meningiomas, frequent use of the micro-Doppler probe to map the course of these
shifting arteries is recommended.

Effective skull base reconstruction is required due to the inevitable Grade 3 CSF leak and large skull base
defect. This reconstruction is performed similarly to the transplanum/transtuberculum approach with a
multilayered closure involving a fat graft to fill the dead space, collagen sponge, nasoseptal flap, solid bony
[31]
or synthetic buttress and tissue glue. A lumbar drain is not used in our practice .

Outcomes
A recent systematic review found that gross total resection of olfactory groove meningiomas through an
endoscopic endonasal transcribriform approach was achieved in 69.5% of patients . Comparison studies
[53]
have consistently reported higher rates of gross total resection with traditional transcranial approaches at
approximately 93% [21,42,43,54-61] . While surgeon experience with the transcribriform approach leads to increased
rates of gross total resection, tumor size (greater than 4 cm), lateral extension beyond the midorbital line,
tumor calcifications, significant brain edema and neurovascular encasement limit success. Olfactory groove
meningiomas that extend posterior to the optic apparatus may cause visual symptoms, particularly when
optic canal invasion is present. In a recent systematic review by Shetty et al. , 80.7% of patients with vision
[18]
symptoms experienced an improvement after endoscopic endonasal surgery, compared to 12.8% of
transcranial approaches. No vision deterioration was reported in the endonasal cohort. Similar to