Olfactory dysfunction in children with Kallmann syndrome: relation of smell tests with brain magnetic resonance imaging.

OBJECTIVE Kallmann syndrome (KS) is a genetic disorder with the distinctive features of hyposmia or anosmia and hypogonadotropic hypogonadism. Though hyposmia/anosmia can be evaluated by both objective and subjective smell tests, there is no study comparing these two methods in KS. The aim of the present case series was to discuss the results of objective and subjective smell tests and compare them to volumetric magnetic resonance imaging (MRI). METHODS A total of six adolescent males (aged between 14-18 years) with KS were examined by objective and subjective olfactometry to test smell function and by specific MRI sequences to measure the olfactory bulbs. RESULTS The objective smell test showed anosmia in all six of the patients. However, the subjective test revealed anosmia in five patients and hyposmia in one patient. Brain MRI showed olfactory bulb aplasia in all six cases. CONCLUSION MRI provides robust evaluation of the olfactory bulb volume. Our data show excellent compatibility between the results obtained via objective olfactometry and those obtained by measuring olfactory bulb volume as determined by MRI and therefore demonstrate that objective olfactometry remains a highly reliable test. Furthermore, although the number of subjects studied was small, these data also suggest that cheaper and more easily available subjective tests could be used in preference to the more expensive as well as labor-intensive and time-consuming objective smell tests. In the event of doubts as to the validity of the subjective tests, the objective olfactometry tests can confirm the diagnosis. The bulb volumetric MRI may be also used in difficult cases.