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

Publication date: Available online 24 August 2017
Source:Brazilian Journal of Otorhinolaryngology
Author(s): Murat Salihoglu, Onuralp Kurt, Seyid Ahmet Ay, Kamil Baskoy, Aytug Altundag, Muzaffer Saglam, Ferhat Deniz, Hakan Tekeli, Arif Yonem, Thomas Hummel
IntroductionIdiopathic hypogonadotrophic hypogonadism (IHH) with an olfactory deficit is defined as Kallmann syndrome (KS) and is distinct from normosmic IHH.ObjectiveBecause 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 IHH.MethodsThis case-control study was included 31 controls and 45 IHH 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 (OBV) measurement. The patients were separated into three groups according to orthonasal olfaction: anosmic IHH (aIHH), hyposmic IHH (hIHH) and normosmic IHH (nIHH).ResultsDiscrimination, identification and threshold scores of patients with KS were significantly lower than controls. Threshold scores of patients with nIHH were significantly lower than those of controls, but discrimination and identification scores were not significantly different. Retronasal olfaction was reduced only in the aIHH group compared to controls. Identification of bitter, sweet, sour, and salty tastes was not significantly different when compared between the anosmic, hyposmic, and normosmic IHH groups and controls. OBV was lower bilaterally in all patient groups when compared with controls. The OBV of both sides was found to be significantly correlated with TDI scores in IHH patients.Conclusion1) There were no significant differences in gustatory function between controls and IHH 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 HH group. The current results indicate a continuum from anosmia to normosmia in IHH patients.



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