Introduction
Post-surgical olfactory dysfunction after an endoscopic endonasal approach has been reported in several series, ranging from 0% to 10.9%(1,2). This complication is attributed to surgical resection or excessive instrumentalization of the lateral nasal wall, especially the superior turbinate and the mid-superior part of the middle turbinate, areas that include olfactory epithelium(3).
Even though post-surgical olfactory dysfunction is not an uncommon condition, its treatment remains challenging due to the limited therapeutic options(4,5). Currently, some treatment options have been proposed, like administration of alpha-lipoic acid, theophylline, and corticosteroids. Nonetheless there is no gold standard therapy to treat this condition(4,6).
Recently, olfactory training has shown promising results in improving smell identification, discrimination and threshold for odor detection in patients with postinfectious olfactory dysfunction(5,7–9). Also, a systematic review and meta-analysis published by Pekala et al. 2016, suggests that it may be an effective treatment for olfactory dysfunction due to multiple etiologies(6).
Additionally, it has been reported that olfactory training can induce reorganization in functional connectivity networks in major olfactory areas(8,10,11). Nevertheless, no study has evaluated the effect of olfactory training in patients with post-surgical olfactory dysfunction. The primary objective of this pilot study is to assess the effect of olfactory training in patients with post-surgical olfactory dysfunction using fMRI, while patients undergo an olfactory stimulation protocol. Additionally, as a secondary objective, the effect of olfactory training in olfactory identification was assessed using “Sniffing Sticks Screening Test”.