You have full access to this open access article. Post-infectious olfactory dysfunction PIOD is one of the most common causes of olfactory impairment but has limited treatment options.
Recently, olfactory training OT has been considered an effective treatment method; however, several questions have arisen regarding its optimal scheme. The aim of this study was to assess whether an OT scheme with 8 odors is more effective than the classic OT scheme with 4 odors by comparing psychophysical test results and olfactory bulb OB volumetrics.
In this prospective cohort study, 72 patients with PIOD were included. Of the patients, 38 underwent brain magnetic resonance imaging for OB volumetric assessment before and after treatment. The comparison of the olfactory test results did not show any significant difference between the two study groups, in agreement with the OB volumetrics.
The convex OB showed better test results than the non-convex OB, with significantly better improvement after treatment regardless of OT type. The number of odors did not appear to play a significant role in the effect of the OT. However, the training scheme with more than four odors showed better adherence among the patients in a long-term treatment plan.
The shape of the OB may have prognostic value in clinical assessment and warrants further investigation. Post-infectious olfactory dysfunction PIOD is one of the most common causes of olfactory loss [ 1 ]. The viruses associated with PIOD include several types of rhinoviruses and the influenza virus, parainfluenza virus, EpsteinβBarr virus, human immunodeficiency virus, and novel severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 [ 2 , 3 ].
