Impact of anterior skull base fracture on lateralized olfactory function

Background: Data on the impact of anterior skull base fractures (aSBF) on lateralized olfactory function are missing. The goal of the study was to investigate olfactory function in patients with traumatic brain injury (TBI) due to aSBF separately for each side and assess the frequency of lateralized smell impairment. Methods: Retrospective, single center study of olfactory function in 93 patients with aSBF. Olfactory function was assessed by means of the Sniffin' Sticks test battery for each side of the nose, seloarately.TBI severity was graded according to the Glasgow Coma Scale. Average time interval between olfactory test and trauma was 6.5 years. General olfactory function was defined as the best side out of both nostrils. Results: A total of 50 patients had unilateral and 43 patients bilateral aSBF.The grade of TBI was inversely correlated with olfactory function. General olfactory function was significantly worse in patients with bilateral aSBF compared to patients with unilateral aSBF. Clinically significant side by side differencesin olfactory function were found in 18 and 30% respectively for unilateral and bilateral aSBF. Grade of TBI had no significant impact on side differences. Among patients with unilateral aSBF olfactory function was not significantly different between the fractured and the non-fractured side. Conclusion: The severity of TBI and bilateral ore than unilateral aSBF results in more impaired olfactory unction. Lateralized olfactory deficits were not more frequent in any group, regardless of the fracture type and side.