Olfactory event-related potentials: A new approach for the evaluation of olfaction in nasopharyngeal carcinoma patients treated with chemo-radiotherapy

Objective: Olfactory dysfunction is a possible side effect of chemo-radiotherapy performed in patients affected by nasopharyngeal carcinoma. Self-rating measurements and olfactory event-related potentials were used and compared in order to evaluate the impact of this treatment on the olfactory system. Methods: Nine patients underwent subjective evaluation of olfactory function (using visual analogue scales for olfactory symptoms and quality of life, and a six-item Hyposmia Rating Scale), and a quantitative and objective measurement (olfactory event-related potentials). Results: Spearman's rank correlation analyses highlighted significant relationships between the clinical scales and olfactory event-related potentials. Inter-group analyses showed significant differences in the latency and in the amplitude of olfactory event-related potentials between patients and controls. Conclusion: Taking into account the small sample size and the lack of pre-treatment assessment, olfactory even-trelated potentials seemed to allow a more objective diagnosis of unilateral and bilateral olfactory loss. Moreover, olfactory event-related potentials and subjective scales results were concordant.