Post-traumatic olfactory loss: psychophysical, electrophysiological and neuroradiological findings in three single case studies.

BACKGROUND: Traumatic brain injury is one of the main causes of smell disorders. The degree of olfactory loss may vary and depend on the severity, nature and location of injury within the olfactory system. The diagnosis of disorders of the sense of smell is based on medical history and clinical data supported by psychophysical tests of smell, electrophysiological and neuroimaging measures.
METHODS: This study reports three single clinical cases of post-traumatic anosmia evaluated by Sniffin' Sticks Test, Olfactory Event-Related Potential and Magnetic Resonance Imaging examinations.
RESULTS: The Olfactory Event-Related Potential findings confirmed the presence of functional olfactory impairment in all three post-traumatic patients showing a good correlation with results of the psychophysical testing. In particular, Sniffin' Sticks Test and OERPs allowed to demonstrate the functional nature of post-traumatic olfactory loss, while the MRI identified the location and extent of injury compatible with the olfactory disorder.
CONCLUSIONS: OERPs may have a good clinical application in objective diagnosis of post-traumatic anosmia, especially when the neuroradiological examination does not show lesions compatible with olfactory loss.