Olfactory function after mild traumatic brain injury

Objective: The aim of this study was to determine the incidence of olfactory dysfunction after mild traumatic brain injury (MTBI). Damage to the olfactory bulbs or frontal cortex has been reported in MTBI, but olfactory dysfunction after MTBI has not been studied in a prospective way before. Design: Patients with first-time MTBI were included. Patients' olfactory threshold values (Hyposmia Utility Kit by Olfacto-Labs®) were measured 2 weeks after the trauma. Associations between olfactory threshold values and individual symptoms and S-100B and NSE concentrations were examined, using multiple linear regression analysis, adjusting for the influence of age. Results: Twenty-two per cent of 111 included patients had hyposmia and 4% had anosmia. Thresholds at 2 weeks showed no significant associations with the presence of symptoms at the ER, nor with early concentrations of S-100B or NSE. Conclusions: Although a high prevalence of olfactory dysfunction was found, no correlation was found between olfactory dysfunction and acute parameters of MTBI.