On the origin of olfactory schwannomas: A systematic review and analysis of attachment site variability and clinical...

Olfactory schwannomas (OS) attachment sites include the olfactory groove and cribriform plate, the anterior skull base, falx cerebri, crista galli, orbit and the planum sphenoidale. This literature review aims to characterize outcomes associated with OS attachment sites.

A literature review was conducted utilizing PubMed. Only studies describing OS and the tumor's origin were included. The primary outcomes of interest were anosmia outcomes and tumor characteristics.

Thirty-eight studies including 42 cases of OS were included. 71.4% (n = 30) of OS originated from the olfactory groove or cribriform plate, while the remaining 28.6% (n = 12) had attachment sites elsewhere in the anterior fossa. 59.5% of cases eroded into the ethmoid bone, 45.2% of tumors had cystic components, 42.9% were encapsulated, 21.4% were hypervascular, and 21.4% had associated calcification. Dural attachment was described in 35.7% of cases. All patients reported subjective improvement in symptoms and there was no significant morbidity or mortality. Gross total resection was reported in 93.0% cases. Post-operative complications occurred in 11.9%. Persistent of anosmia was noted in 24.1% cases and improved anosmia was documented in 31.0% cases. OS site of origin had no impact on risk of anosmia or post-operative complications.

Microsurgical resection of OS is associated with excellent clinical outcomes, resection rates, and low morbidity and recurrence rates. Contrary to prior assertions, there was no statistically significant difference in outcomes based on tumor attachment site.