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J Neurol Surg A Cent Eur Neurosurg 2020; 81(04): 310-317
DOI: 10.1055/s-0040-1709165
Original Article
Georg Thieme Verlag KG Stuttgart · New York

Olfaction in Olfactory Groove Meningiomas

Michaela Dedeciusova
1   Department of Neurosurgery and Neurooncology, First Faculty of Medicine, Charles University and Military University Hospital, Prague, Czech Republic
,
Norbert Svoboda
1   Department of Neurosurgery and Neurooncology, First Faculty of Medicine, Charles University and Military University Hospital, Prague, Czech Republic
,
Vladimir Benes
1   Department of Neurosurgery and Neurooncology, First Faculty of Medicine, Charles University and Military University Hospital, Prague, Czech Republic
,
Jaromir Astl
2   Department of Otorhinolaryngology and Maxillofacial Surgery, Third Faculty of Medicine, Charles University and Military University Hospital, Prague, Czech Republic
,
David Netuka
1   Department of Neurosurgery and Neurooncology, First Faculty of Medicine, Charles University and Military University Hospital, Prague, Czech Republic
› Author Affiliations
Further Information

Publication History

20 April 2019

30 July 2019

Publication Date:
03 May 2020 (online)

Also available ateRefMedOne
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Abstract

Background Clinical examination, including pre- and postoperative assessment of olfaction, is essential in evaluating surgical outcomes in patients with olfactory groove meningiomas (OGMs). A review of a recent series revealed a lack of assessment of olfaction in most of the studies. Tests determining olfactory detection should be used to reveal olfactory dysfunction. Specialized examination techniques (e.g., electro-olfactography, olfactory evoked potentials, and functional magnetic resonance imaging) are currently used in research.

Methods Prospective analysis of 13 patients who underwent surgical resection of OGMs from December 2013 to December 2017 was performed. Data on clinical presentation, pre- and postoperative neurologic examinations, complications, recurrences, adjuvant treatment, and follow-up outpatient examinations were recorded. Olfactory function was assessed using the Sniffin' Sticks odor identification test preoperatively, postoperatively, and 1 year after surgery.

Results All the meningiomas were resected via unilateral craniotomy, and gross total resection was achieved in all cases. Surgery-related permanent morbidity was 7.7% and overall mortality 0%. For the eight patients with preoperative normosmia, five remained normosmic (62.5%), one deteriorated to hyposmia (12.5%), and two deteriorated to anosmia (25%). For the two patients with preoperative hyposmia, one remained hyposmic and one deteriorated to anosmia. For the three anosmic patients, two remained anosmic, and one improved to hyposmia.

The intact olfactory function preoperatively was associated with a better olfactory outcome. Overall, 62.5% of these patients remained normosmic, and none of the hyposmic or anosmic patients normalized their olfaction.

Higher meningioma volume is associated with worse olfactory function before surgery (normosmia in 16.7% versus 100.0% in less voluminous) and following the surgery (normosmia in 16.7% versus 57.1% less voluminous).

The unilateral surgical approach enabled the anatomical preservation of the contralateral olfactory nerve in 76.9% of our patients. Functional normosmia was achieved in 50% and hyposmia in 30% of these cases.

Conclusions Assessment of olfactory function is both vital in preoperative decision making (surgical approach, radicality of resection) and when evaluating surgical outcome. Preoperative normosmia seems to be the most important prognostic factor for functional olfactory outcome. In normosmic patients the olfaction was preserved in 62.5% of cases. Moreover, higher meningioma volume is associated with worse olfactory function before and following the surgery. The greatest advantage of the unilateral surgical approach is anatomical preservation of the contralateral olfactory nerve with a satisfactory functional outcome. These results support a proactive approach, with early surgical resection using a unilateral approach even in cases with less voluminous OGMs that enables the preservation of olfactory function in a significant proportion of patients.

Keywords

olfactory groove meningioma - olfactory function - olfaction - surgical approach

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.