Olfactory Groove and Planum Sphenoidale Meningiomas

Olfactory groove meningiomas (OGMs) and planum sphenoidale meningiomas (PSMs) are usually midline tumor occurring along the anterior cranial base from the crista galli and cribriform plate to the limbus sphenoidale and chiasmatic sulcus. OGMs usually became large before diagnosis causing cognitive or behavior changes; anosmia are often present at diagnosis and visual impairment is evident in one-third of patients. PSMs are more frequently associated with visual abnormalities, because they can cause displacement of the optic nerves, inferiorly. Surgery is a safe and effective treatment. We recommend an anterior midline skull base approach, the trans-frontal-sinus subcranial route, or the antero-lateral fronto-orbital approach when involvement of anterior cerebral arteries is evident. In our experience, gross total resection (GTR), defined as Simpson 1–3, was achieved in all cases adopting these two approaches, but recurrence is not uncommon. The cumulative recurrence-free survival after GTR at 5 and 10 years was 87.5% and 77.8%; for this reason, we recommended Gamma Knife Stereotactic Radiosurgery (GKSRS) as adjuvant treatment when residual or recurrent tumor is evident after surgery. GKSRS can be proposed even as up-front treatment, in small asymptomatic OGMs and PSMs.