Correlation of olfactory phenotype by Indian smell identification test and quantitative MRI of olfactory apparatus in idiopathic hypogonadotropic hypogonadism

• Published in: Indian journal of endocrinology and metabolism Vol. 23; no. 3; pp. 367 - 372
• Main Authors: Nehara, Hardeva, Sharma, Balram, Kumar, Anshul, Saran, Sanjay, Mangalhara, Naresh, Mathur, Sandeep
• Format: Journal Article
• Language: English
• Published: India Wolters Kluwer India Pvt. Ltd 01.05.2019; Medknow Publications and Media Pvt. Ltd; Medknow Publications & Media Pvt. Ltd; Wolters Kluwer - Medknow; Wolters Kluwer Medknow Publications
• Subjects: Diagnostic imaging; Endocrinology; Hypogonadism; Hypogonadotropic hypogonadism; Kallmann syndrome; Magnetic resonance imaging; Medical research; NMR; Nuclear magnetic resonance; Olfaction disorders; olfactory bulb; Original; Patients; Puberty; smell test; Standard deviation; Studies; India; Hypogonadotropic hypogonadism; olfactory bulb; smell test; Kallmann syndrome
• ISSN: 2230-8210; 2230-9500
• DOI: 10.4103/ijem.ijem_28_19

Objectives: Idiopathic hypogonadotropic hypogonadism (IHH) can be associated with anosmia/hyposmia. The objective of this study is to evaluate olfaction by Indian smell identification test (INSIT) and measure olfactory bulbs (OBs) and sulci using dedicated magnetic resonance imaging (MRI) in patients with IHH and correlate MRI findings with INSIT. Methods: Forty patients with IHH underwent (a) brief smell identification test (INSIT) and (b) MRI of the olfactory apparatus. The size of olfactory sulcus and bulb was quantified and compared with the normative data obtained in 22 controls. The agreement between INSIT and MRI was assessed using Kappa index. Results: Of the 40 patients, 8 patients who reported abnormal smell sensation and 12 of the remaining 32 patients who reported normal smell sensation historically had a low score on INSIT. Thus, there were 20 patients with Kallmann syndrome (KS) and the rest 20 were normosmic IHH (nIHH). Of 40 patients with IHH, MRI finding was suggestive of normal (n = 16), hypoplastic (n = 12), and aplastic (n = 12) olfactory apparatus. All 20 patients with KS have olfactory abnormalities (n = 12 aplastic, n = 8 hypoplastic), and 4 of 20 nIHH have olfactory abnormalities (hypoplastic only) on MRI. There is (a) significant positive correlation (r = 0.54, P = 0.013) between the OB volume (MRI) and smell test scores and (b) moderate agreement (Kappa index: 0.49) between smell defect (INSIT score ≤ 4) and aplastic olfactory apparatus. Conclusion: Self-reporting of smell significantly underestimates olfactory phenotype, and hence we recommend an objective smell test to differentiate KS from nIHH. Olfactory phenotype significantly correlates with MRI quantification of olfactory apparatus in IHH.