• Boris R Haxel, Leah Grant, and Alan Mackay-Sim.
• Department of Otolaryngology, Head and Neck Surgery, University of Mainz, School of Medicine, Mainz, Germany. haxel@hno.klinik.uni-mainz.de
• J Head Trauma Rehabil. 2008 Nov 1;23(6):407-13.

ObjectiveTo determine the incidence of olfactory dysfunction after head trauma using clinical and radiologic findings, quantitative assessment, and electro-physiologic methods.ParticipantsA total of 190 patients with head trauma of different severity (n = 32 with mild traumatic brain injury (TBI), n = 94 with signs of moderate TBI, and n = 64 with severe TBI) 6 to 32 months prior to the study.DesignPatients were selected retrospectively, surveyed by telephone (n = 190), and screened for olfactory function with Brief Smell Identification Test (n = 82). Those with olfactory dysfunction were assessed as outpatients using the Sniffin' Sticks (n = 19) and olfactory-evoked potential recording (n = 16).ResultsTwenty-one participants (11%) reported a decreased sense of smell after trauma. The incidence of olfactory dysfunction after head injury was 12.8%. The results of the odor-evoked potentials were heterogeneous. A significant correlation was found between olfactory dysfunction and the appearance of skull base fractures and intracranial hemorrhage or hematoma.ConclusionThe site of trauma may be more relevant to prognosis than a simple probability (of olfactory loss) based on incidence. Odor-evoked potentials indicate that functional anosmia can occur even when there is some evidence of intact olfactory nerve function.

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