What are the causative viruses in patients with postviral olfactory dysfunction onset (PVOD), and what are their mechanisms?
BOTTOM LINE: Rhinovirus (RV), coronavirus (CoV), parainfluenza virus (PIV), and Epstein-Barr virus (EBV) are associated with PVOD, and RVs may cause olfactory dysfunction by means other than nasal obstruction and in varying severities and time courses.
BACKGROUND: Viral upper respiratory infection (URI) is a commonly identified cause of olfactory dysfunction. RVs are the most frequently isolated respiratory pathogen that infects all age groups, yet there is no documented association between RVs and post-URI olfactory dysfunction. Clinical evidence regarding the causative viruses of olfactory dysfunction has not been investigated.
STUDY DESIGN: Case-control study.
SETTING: Department of Otorhinolaryngology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan.
SYNOPSIS: Researchers collected nasal discharge from 24 patients with PVOD to investigate the presence of 10 viruses, including RVs, CoVs, influenza viruses (IVs), PIVs, respiratory syncytial viruses (RSVs), adenoviruses (AdVs), enteroviruses (EVs), EBVs, herpes simplex viruses (HSVs), and varicella-zoster viruses (VZVs). Using subjective assessment questionnaires, acoustic rhinometry, and olfactory tests, the team examined the time course with regard to changes in olfactory dysfunction and nasal obstruction in these patients. Follow-up exams were performed at two, four, eight, 11, and 24 weeks after first visits. From eight weeks on, patients received treatment with oral prednisolone. Viruses that could be identified by both electrophoresis and sequencing or southern hybridization were found in 11 patients. Of these, investigators confirmed four patients with RV, three with EBV, one with PIV, one with CoV, and two with picornavirus (unclassified respiratory virus). Overall, findings pinpointed RVs, CoVs, PIVs, and EBVs as potential PVOD causes. Additional analysis suggested that RVs cause olfactory dysfunction through mechanisms other than nasal obstruction and can also induce various severities and time courses of olfactory dysfunction.
CITATION: Suzuki M, Saito K, Min W, et al. Identification of viruses in patients with postviral olfactory dysfunction. Laryngoscope. 2007;117:272-277.