Skip Navigation LinksHome > September/October 2013 - Volume 37 - Issue 5 > Anatomic Olfactory Structural Abnormalities in Congenital Sm...
Journal of Computer Assisted Tomography:
doi: 10.1097/RCT.0b013e31829bfa3b
Neuroradiology

Anatomic Olfactory Structural Abnormalities in Congenital Smell Loss: Magnetic Resonance Imaging Evaluation of Olfactory Bulb, Groove, Sulcal, and Hippocampal Morphology

Levy, Lucien M. MD, PhD*; Degnan, Andrew J. MD, MPhil*†; Sethi, Ila MD*; Henkin, Robert I. MD, PhD

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Abstract

Background and Purpose

There are 2 groups of patients with congenital smell loss: group 1 (12% of the total), in which patients exhibit a familial smell loss in conjunction with severe anatomical, somatic, neurological, and metabolic abnormalities such as hypogonadotropic hypogonadism; and a larger group, group 2 (88% of the total), in which patients possess a similar degree of smell loss but without somatic, neurological, or anatomical abnormalities or hypogonadism. Both groups are characterized by similar olfactory dysfunction, and both have been reported to have absent or decreased olfactory bulbs and grooves, which indicates some overlap in olfactory pathophysiology and anatomy. The purpose of this study was to evaluate patients with congenital smell loss, primarily among group 2 patients, comparing brain magnetic resonance imaging (MRI) results in patients with types of hyposmia.

Methods

Forty group 2 patients were studied by measurements of taste (gustometry) and smell (olfactometry) function and by use of MRI in which measurements of olfactory bulbs, olfactory sulcus depth, olfactory grooves, and hippocampal anatomy were performed. Anatomical results were compared with similar studies in group 1 patients and in 22 control subjects with normal sensory function.

Results

Olfactometry was abnormal in all patients with no patient reporting ever having normal olfaction. No patient had a familial history of smell loss. On MRI, all exhibited at least 1 abnormality in olfactory system anatomy, including absence or decreased size of at least 1 olfactory bulb, decreased depth of an olfactory sulcus, and abnormalities involving hippocampal anatomy with hippocampal malrotations. One patient had bilateral bulb duplication. Normal subjects with normal smell and taste function exhibited some but very few or significant neuroanatomical changes on MRI.

Conclusions

Although both groups have similar abnormalities of smell function, group 2 patients demonstrate anatomical anomalies in olfactory structures that are neither as common nor as severe as in group 1 patients. Group 2 patients can have a wide range of olfactory anatomical abnormalities.

Copyright © 2013 by Lippincott Williams & Wilkins

 

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