Objective: To investigate changes of olfactory bulb (OB) volume over time in relation to olfactory function.
Design: Prospective, before-after trial.
Setting: Outpatient clinic of a university clinic for otorhinolaryngology.
Patients: A total of 20 patients with olfactory loss participated in the study. The duration of olfactory deficits ranged from 3 months to 6 years.
Main outcome measures: Olfactory function was assessed for phenyl ethyl alcohol odor threshold, odor discrimination, and odor identification. Olfactory bulb volume was determined using magnetic resonance imaging.
Results: In initially hyposmic patients (n = 13), changes in OB volume were found to correlate with odor threshold changes (r = 0.82; P = .001); no such correlation was found for odor discrimination or odor identification.
Conclusion: As demonstrated in a longitudinal study for the first time to our knowledge, the human OB is a highly plastic structure that responds to individual changes in olfactory status.