Abstract

The olfactory apparatus, consisting of the bulb and tract, is readily identifiable on MR imaging. Anomalous development of the olfactory apparatus may be the harbinger of anomalies of the secondary olfactory cortex and associated structures. We report a large single-site series of associated MR imaging findings in patients with olfactory anomalies. A retrospective search of radiologic reports (2010 through 2014) was performed by using the keyword "olfactory"; MR imaging studies were reviewed for olfactory anomalies and intracranial and skull base malformations. Medical records were reviewed for clinical symptoms, neuroendocrine dysfunction, syndromic associations, and genetics. We identified 41 patients with olfactory anomalies (range, 0.03-18 years of age; M/F ratio, 19:22); olfactory anomalies were bilateral in 31 of 41 patients (76%) and absent olfactory bulbs and olfactory tracts were found in 56 of 82 (68%). Developmental delay was found in 24 (59%), and seizures, in 14 (34%). Pituitary dysfunction was present in 14 (34%), 8 had panhypopituitarism, and 2 had isolated hypogonadotropic hypogonadism. CNS anomalies, seen in 95% of patients, included hippocampal dysplasia in 26, cortical malformations in 15, malformed corpus callosum in 10, and optic pathway hypoplasia in 12. Infratentorial anomalies were seen in 15 (37%) patients and included an abnormal brain stem in 9 and an abnormal cerebellum in 3. Four patients had an abnormal membranous labyrinth. Genetic testing was performed in 23 (56%) and findings were abnormal in 11 (48%). Olfactory anomalies should prompt careful screening of the brain, skull base, and the pituitary gland for additional anomalies. Genetic testing should be considered.

Highlights

  • BACKGROUND AND PURPOSEThe olfactory apparatus, consisting of the bulb and tract, is readily identifiable on MR imaging

  • Syndromes associated with malformed primary olfactory pathways include Kallmann syndrome; CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities [hypogonadism], Ear anomalies and/or deafness); septo-optic dysplasia; and craniotelencephalic dyspla

  • Linking the formation of the cerebellar vermis and olfactory apparatus is the transcription factor zinc finger protein 423, which has been shown to be a requirement for patterning the development of precursors in the cerebellar vermis and olfactory apparatus in rats.[9]

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Summary

Methods

A retrospective search of radiologic reports (2010 through 2014) was performed by using the keyword “olfactory”; MR imaging studies were reviewed for olfactory anomalies and intracranial and skull base malformations. Medical records were reviewed for clinical symptoms, neuroendocrine dysfunction, syndromic associations, and genetics. The study was approved by the Institutional Internal Review Board (University of Texas Southwestern Medical Center) and is Health Insurance Portability and Accountability Act– compliant. A retrospective search of radiologic reports was performed at a tertiary pediatric hospital by using the keyword “olfactory” with inclusive dates of January 2010 to December 2014. The presence and position of the neurohypophysis were documented, along with the presence of the infundibulum. The directionally encoded color maps from diffusion imaging were reviewed in a subset of patients for anomalies of major commissural, association, and projection fibers

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