To determine the incidence of olfactory dysfunction after head trauma using clinical and radiologic findings, quantitative assessment, and electro-physiologic methods.
A 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.
Patients 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).
Twenty-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.
The 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.
From the Department of Otolaryngology, Head and Neck Surgery, University of Mainz, School of Medicine, Mainz, Germany (Dr Haxel); and Eskitis Institute for Cell and Molecular Therapies, Griffith University, Nathan, Queensland, Australia (Drs Haxel and Mackay-Sim and Ms Grant).
Corresponding author: Boris R. Haxel, MD, Department of Otorhinolaryngology, Mainz Medical School, Langenbeckstr. 1, D-55101, Mainz, Germany (e-mail: email@example.com).
This study was supported by a grant of the Deutsche Forschungsgemeinschaft HA-3447/1-1, Germany, and by the Garnett Passe and Rodney Williams Memorial Foundation, Australia.
Thanks to the staff of the Department of Otolaryngology, Head and Neck Surgery (head: Prof W. Coman) and the Department of Neurosurgery (head: Dr A. Nowitzke) at the Princess Alexandra Hospital for the support in selection of patients.