Reconsidering olfactory bulb magnetic resonance patterns in Kallmann syndrome

Abstract

Objective: The aim of this retrospective study was to perform magnetic resonance imaging assessment of olfactory pathway and skull base abnormalities in Kallmann syndrome (KS) patients with hypogonadotropic hypogonadism and olfaction disorder.

Methods: Magnetic resonance brain patterns were retrospectively studied in 19 patients clinically classified as KS. Qualitative assessment of olfactory bulb region comprised bulb atrophy and rectus and medial orbital gyrus ptosis; quantitative assessment measured olfactory fossa depth and width, sulcus depth and ethmoid angle. Results were compared to an age- and sex-matched control population (n=19) with no impairment in the region of interest. Sixteen of the 19 KS patients were genetically screened for mutations associated with KS.

Results: On the above qualitative criteria, 15 of the 19 patients presented either unilateral (n=2) or bilateral (n=13) olfactory bulb agenesis; 16 showed tract agenesis and 16 showed gyrus malformation (ptosis or absence). On the quantitative criteria, 18 of the 19 patients showed abnormal sulcus depth and/or olfactory fossa malformation and/or abnormal ethmoid angle.

Conclusion: The presence of malformation abnormalities in the olfactory fossae of 18 of the 19 patients appears to be a key factor for etiological diagnosis of hypogonadotropic hypogonadism, and should enable targeted study of genes involved in KS.

Keywords: Anosmie; Bulbe olfactif; Hypogonadism; Hypogonadisme; Imagerie par résonnance magnétique; Kallmann syndrome; Magnetic resonance imaging; Olfaction Disorder; Olfactory bulb; Syndrome de Kallmann.