Olfactory Bulb Volume Is Indicator of Smell Function

In patients with impaired sense of smell, improving function correlates with higher olfactory bulb volume

THURSDAY, June 19 (HealthDay News) -- Olfactory bulb volume is a useful prognostic indicator of impaired sense of smell caused by trauma or infection because of its plasticity and responsiveness to individual changes in olfactory function, according to a report in the June issue of the Archives of Otolaryngology -- Head & Neck Surgery.

Antje Haehner, M.D., of the University of Dresden Medical School in Dresden, Germany, and colleagues conducted a prospective, longitudinal study of 20 clinic patients with olfactory function loss (14 were post-infection, six were post-trauma). At the time of the study, subjects had been impaired for three months to six years. Olfactory function was evaluated using standard measures (phenyl ethyl alcohol odor threshold, odor discrimination, and odor identification), while MRI scans established olfactory bulb volume.

Changes in olfactory threshold function correlated directly to changes in olfactory bulb volume, regardless of age or gender, with improving thresholds leading to higher volume, the researchers found. The correlation, however, did not hold for odor discrimination and odor identification deficits. The study results indicate, for the first time in a longitudinal study in humans, the plasticity of the olfactory system.

"The correlation between olfactory bulb volume and olfactory function may potentially be used in combination with other factors influencing olfaction such as remaining olfactory function, age, and duration of olfactory loss, as a means to provide patients with individual information on the prognosis of their disease," the authors conclude.

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