Is There an Association Between Olfactory Bulb Volume and the Keros Type of Fossa Olfactoria?:

Anterior Skull Base Abnormalities in Congenital Anosmia

INTRODUCTION

The structures of the skull and the brain are related to each other. Prior work in individuals with isolated congenital anosmia (ICA) showed that these individuals were characterized by olfactory bulb (OB) defects. The aim of this study was to compare the morphological pattern of the anterior skull base surrounding the OB between individuals with ICA and normosmic controls. We meant to investigate whether these features can help distinguish abnormalities from normal variation.

METHODS

We conducted a retrospective study to acquire T2-weighted magnetic resonance images from individuals diagnosed with ICA (n = 31) and healthy, normosmic controls matched for age and gender (n = 62). Between both groups, we compared the depth and width of the olfactory fossa, the angle of the ethmoidal fovea, as well as the angle of the lateral lamella of the cribriform plate. Within the ICA group, we further performed subgroup analyses based on the presence or absence of the OB, to investigate whether the morphology of the anterior skull base relates to the presence of OBs. The diagnostic performance of these parameters was evaluated using receiver operating characteristic analysis.

RESULTS

Individuals with ICA exhibited a flattened ethmoid roof and shallower olfactory fossa when compared to controls. Further, the absence of the OB was found to be associated with a higher degree of flattening of the ethmoid roof and a shallow olfactory fossa. We reached the results in the following areas under the receiver operating characteristic curves: 0.80 - angle of fovea ethmoidalis, 0.76 - depth of olfactory fossa, 0.70 - angle of lateral lamella of the cribriform plate for significant differentiation between individuals with ICA and normosmic controls.

CONCLUSION

Individuals with ICA exhibited an unusual anterior skull base surrounding the OB. This study supports the idea of an integrated development of OB and anterior skull base. Hence, the morphological pattern of the anterior skull base surrounding the OB helps distinguish individuals with ICA from normosmic controls and may therefore be useful for the diagnosis of ICA, although it is certainly not an invariable sign of congenital anosmia.

Ambiguous "olfactory" terms for anatomic spaces adjacent to the cribriform plate: A publication database analysis and quest for uniformity

A precise nomenclature and terminology is the foundation of communication in Anatomy and related biomedical sciences. The olfactory bulbs and nerves lie above and below the cribriform plate (CP), respectively. Hence, many anatomical landmarks in this region have names adopting the term "olfactory" as qualifiers. Ambiguous use of these "olfactory" terms exists, with some potential repercussions on patient treatments. We performed a publication database analysis to determine the frequency of misuse of names for seven anatomical "olfactory" spaces close to the CP and nasal cavity. We searched PubMed® publications having the keyword "olfactory" in their title or abstract, plus one of seven other keywords: "groove", "fossa", "recess", "cleft", "vestibule", "sulcus", and "cistern". We reviewed all abstracts for accuracy of these terms relative to accepted norms or customary definitions. By February 2020, we found all these keywords in 1255 articles. For the terms olfactory "groove" and "fossa", the number of relevant articles (and percentage of those inaccurately using these terms) were 374 (1.1%), and 49 (8.2%), respectively. All 52 abstracts containing "olfactory" and "vestibule" were irrelevant, relating to the "nasal vestibule" and olfactory function, instead of "olfactory vestibule". Overall, terms used to describe "olfactory" spaces near the CP are seldom ambiguous or inaccurate, but the terms olfactory "groove" and "fossa" are occasionally misused, We propose several new "olfactory" terms for inclusion in the Terminologia Anatomica, and stress the need for uniform nomenclature leading to greater consistency and accuracy in clinical use of anatomical terms containing the word "olfactory" as a descriptor.

Cribriform Plate, Crista Galli, Olfactory Fossa and Septal Deviation

OBJECTIVES

In the present study, we investigated the relationship between olfactory fossa, cribriform plate, crista galli and nasal Septal Deviation (SD). Keros classification of olfactory fossa was also performed.

METHODS

This study was performed retrospectively. Computerized Tomography (CT) images of 200 adult subjects were observed. Unilateral nasal Septal Deviation (SD) cases were included into the study. On coronal CT scans, SD side and location, SD angle, cribriform plate width, olfactory fossa depth (Keros classification) and width, area of the olfactory fossa, crista galli length, width and pneumatization were evaluated.

RESULTS

Anterior and anteroposterior deviations were detected mainly. In females, 64.0% and in males, 45.3% of the SDs were located anteriorly. In males, anteroposterior SDs (40.0%) were detected more than females. In anteroposterior SDs, SD angle was higher than anterior SDs. With higher SD angle, crista galli width and height decreased. Cribriform plate width, olfactory fossa height, width and area values of contralateral side were significantly higher than those of the ipsilateral side. For Keros classification, in male group, type 1 (53.3%) and in females, type 2 (57.6%) was detected at ipsilateral side. For contralateral side, type 2 Keros was detected in both genders. Complete crista galli pneumatization was observed in 4.0% and partial pneumatization was detected in 12.0%. In 84% of the patients, there is no Crista galli pneumatization. With the presence of pneumatized crista galli, contralateral Keros values decreased. Crista galli height and contralateral olfactory fossa width showed positive correlation. In older patients, cribriform plate width decreased.

CONCLUSION

In our study, there was no Keros type 3 olfactory fossa. In males' contralateral side of SD; and in females both ipsilateral and contralateral side of SD, Keros type 2 olfactory fossa were detected. Therefore, during sinus surgery, surgeons should work carefully not to made intracranial penetration.

Retro- and orthonasal olfactory function in relation to olfactory bulb volume in patients with hypogonadotrophic hypogonadism

Introduction

Idiopathic hypogonadotrophic hypogonadism with an olfactory deficit is defined as Kallmann syndrome and is distinct from normosmic idiopathic hypogonadotrophic hypogonadism.

Objective

Because olfactory perception not only consists of orthonasally gained impressions but also involves retronasal olfactory function, in this study we decided to comprehensively evaluate both retronasal and orthonasal olfaction in patients with idiopathic hypogonadotrophic hypogonadism.

Methods

This case-control study included 31 controls and 45 idiopathic hypogonadotrophic hypogonadism patients. All participants whose olfactory and taste functions were evaluated with orthonasal olfaction (discrimination, identification and threshold), retronasal olfaction, taste function and olfactory bulb volume measurement. The patients were separated into three groups according to orthonasal olfaction: anosmic idiopathic hypogonadotrophic hypogonadism, hyposmic idiopathic hypogonadotrophic hypogonadism and normosmic idiopathic hypogonadotrophic hypogonadism.

Results

Discrimination, identification and threshold scores of patients with Kallmann syndrome were significantly lower than controls. Threshold scores of patients with normosmic idiopathic hypogonadotrophic hypogonadism. were significantly lower than those of controls, but discrimination and identification scores were not significantly different. Retronasal olfaction was reduced only in the anosmic idiopathic hypogonadotrophic hypogonadism group compared to controls. Identification of bitter, sweet, sour, and salty tastes was not significantly different when compared between the anosmic, hyposmic, and normosmic idiopathic hypogonadotrophic hypogonadism groups and controls. Olfactory bulb volume was lower bilaterally in all patient groups when compared with controls. The olfactory bulb volume of both sides was found to be significantly correlated with threshold, discrimination and identification scores in idiopathic hypogonadotrophic hypogonadism patients.

Conclusion

1) There were no significant differences in gustatory function between controls and idiopathic hypogonadotrophic hypogonadism patients; 2) retronasal olfaction was reduced only in anosmic patients but not in orthonasally hyposmic participants, possibly indicating presence of effective compensatory mechanisms; 3) olfactory bulb volumes were highly correlated with olfaction scores in the hypogonadotrophic hypogonadism group. The current results indicate a continuum from anosmia to normosmia in idiopathic hypogonadotrophic hypogonadism patients.