Abstract
Purpose
Prognostic assessment of patients with post-infectious olfactory dysfunction (PIOD) poses a challenge for clinicians. While there have been some studies on the prognostic factors of PIOD focusing on demographic factors, the aim of this study was to investigate whether event-related potentials (ERPs) could be used as a new predictor of olfactory recovery in PIOD.
Methods
This was a retrospective study involving patients who underwent olfactory examinations using Sniffin’ Sticks test before treatment and after 1 year of follow-up. The responder group was defined by an increase of threshold–discrimination–identification (TDI) score of ≥ 6 points. All patients underwent ERP examination and the amplitude and latency of each wave of ERPs were recorded before treatment.
Results
A total of 61 patients (age 47.50 ± 11.04 years, 27 males) were analyzed. The presence of olfactory ERPs (oERPs) was greater in the responder group than in the non-responder group (P = 0.007), while that of trigeminal ERPs (tERPs) did not differ between the two groups (P = 0.346). Logistic-regression analyses showed that factors associated with improvement of subjective olfactory function were duration (OR, 1.604; 95% CI, 1.062–2.423; P = 0.025), initial threshold (odds ratio [OR], 0.043; 95% confidence interval [CI], 0.004–0.439; P = 0.008), and latency of N1 in oERPs (OR, 1.007; 95% CI, 1.001–1.013; P = 0.021).
Conclusion
Our study shows that duration of OD, initial threshold, and latency of N1 in oERPs were associated with olfactory improvement in PIOD patients, which may provide guidance for clinicians.
This is a preview of subscription content, access via your institution.



References
Rawal S, Hoffman HJ, Bainbridge KE et al (2016) Prevalence and risk factors of self-reported smell and taste alterations: results from the 2011–2012 US National Health and Nutrition Examination Survey (NHANES). Chem Senses 41(1):69–76
Seubert J, Laukka EJ, Rizzuto D et al (2017) Prevalence and correlates of olfactory dysfunction in old age: a population-based study. J Gerontol A Biol Sci Med Sci 72(8):1072–1079
Damm M, Temmel A, Welge-Lüssen A et al (2004) Olfactory dysfunctions. Epidemiology and therapy in Germany, Austria and Switzerland. HNO 52(2):112–120
Hummel T, Whitcroft KL, Andrews P et al (2016) Position paper on olfactory dysfunction. Rhinology 56(1):1–30
Fokkens WJ, Lund VJ, Hopkins C et al (2020) european position paper on rhinosinusitis and nasal polyps 2020. Rhinology 58(Suppl S29):1–464
Potter MR, Chen JH, Lobban NS et al (2020) Olfactory dysfunction from acute upper respiratory infections: relationship to season of onset. Int Forum Allergy Rhinol 10(6):706–712
Durrant DM, Ghosh S, Klein RS (2016) The olfactory bulb: an immunosensory effector organ during neurotropic viral infections. ACS Chem Neurosci 7(4):464–469
Harless L, Liang J (2016) Pharmacologic treatment for postviral olfactory dysfunction: a systematic review. Int Forum Allergy Rhinol 6(7):760–767
Kattar N, Do TM, Unis GD, et al (2020) Olfactory training for postviral olfactory dysfunction: systematic review and meta-analysis. Otolaryngol Head Neck Surg pp 194599820943550
Pekala K, Chandra RK, Turner JH (2016) Efficacy of olfactory training in patients with olfactory loss: a systematic review and meta-analysis. Int Forum Allergy Rhinol 6(3):299–307
Sorokowska A, Drechsler E, Karwowski M et al (2017) Effects of olfactory training: a meta-analysis. Rhinology 55(1):17–26
Hura N, Xie DX, Choby GW et al (2020) Treatment of post-viral olfactory dysfunction: an evidence-based review with recommendations. Int Forum Allergy Rhinol 10(9):1065–1086
Hummel T, Whitcroft KL, Rueter G et al (2017) Intranasal vitamin A is beneficial in post-infectious olfactory loss. Eur Arch Otorhinolaryngol 274(7):2819–2825
Whitcroft KL, Ezzat M, Cuevas M et al (2017) The effect of intranasal sodium citrate on olfaction in post-infectious loss: results from a prospective, placebo-controlled trial in 49 patients. Clin Otolaryngol 42(3):557–563
Kim DH, Kim SW, Hwang SH et al (2017) Prognosis of olfactory dysfunction according to etiology and timing of treatment. Otolaryngol Head Neck Surg 156(2):371–377
Kobal G, Hummel T (1994) Olfactory (chemosensory) event-related potentials. Toxicol Ind Health 10(4–5):587–596
Rombaux P, Huart C, Mouraux A (2012) Assessment of chemosensory function using electroencephalographic techniques. Rhinology 50(1):13–21
Evans WJ, Cui L, Starr A (1995) Olfactory event-related potentials in normal human subjects: effects of age and gender. Electroencephalogr Clin Neurophysiol 95(4):293–301
Gudziol H, Guntinas-Lichius O (2019) Electrophysiologic assessment of olfactory and gustatory function. Handb Clin Neurol 164:247–262
Pause BM, Krauel K (2000) Chemosensory event-related potentials (CSERP) as a key to the psychology of odors. Int J Psychophysiol 36(2):105–122
Lundström JN, Olsson MJ, Schaal B et al (2006) A putative social chemosignal elicits faster cortical responses than perceptually similar odorants. Neuroimage 30(4):1340–1346
Ciurleo R, Bonanno L, De Salvo S et al (2018) Olfactory dysfunction as a prognostic marker for disability progression in multiple sclerosis: an olfactory event related potential study. PLoS ONE 13(4):e0196006
Liu J, Pinto JM, Yang L et al (2016) Gender difference in Chinese adults with post-viral olfactory disorder:a hospital-based study. Acta Otolaryngol 136(9):976–981
Hummel T, Sekinger B, Wolf SR et al (1997) “Sniffin” sticks’: olfactory performance assessed by the combined testing of odor identification, odor discrimination and olfactory threshold. Chem Senses 22(1):39–52
Hummel T, Lötsch J (2010) Prognostic factors of olfactory dysfunction. Arch Otolaryngol Head Neck Surg 136(4):347–351
Lötsch J, Hummel T (2006) The clinical significance of electrophysiological measures of olfactory function. Behav Brain Res 170(1):78–83
Yang L, Wei Y, Yu D et al (2010) Olfactory and gustatory function in healthy adult Chinese subjects. Otolaryngol Head Neck Surg 143(4):554–560
Hummel T, Bensafi M, Nikolaus J et al (2007) Olfactory function in children assessed with psychophysical and electrophysiological techniques. Behav Brain Res 180(2):133–138
Gottschlich M, Hummel T (2015) Effects of handedness on olfactory event-related potentials in a simple olfactory task. Rhinology 53(2):149–153
Huart C, Rombaux P, Hummel T et al (2013) Clinical usefulness and feasibility of time-frequency analysis of chemosensory event-related potentials. Rhinology 51(3):210–221
Hummel T, Rissom K, Reden J et al (2009) Effects of olfactory training in patients with olfactory loss. Laryngoscope 119(3):496–499
Damm M, Pikart LK, Reimann H et al (2014) Olfactory training is helpful in postinfectious olfactory loss: a randomized, controlled, multicenter study. Laryngoscope 124(4):826–831
London B, Nabet B, Fisher AR et al (2008) Predictors of prognosis in patients with olfactory disturbance. Ann Neurol 63(2):159–166
Lee DY, Lee WH, Wee JH et al (2014) Prognosis of postviral olfactory loss: follow-up study for longer than one year. Am J Rhinol Allergy 28(5):419–422
Reden J, Mueller A, Mueller C et al (2006) Recovery of olfactory function following closed head injury or infections of the upper respiratory tract. Arch Otolaryngol Head Neck Surg 132(3):265–269
Hedner M, Larsson M, Arnold N et al (2010) Cognitive factors in odor detection, odor discrimination, and odor identification tasks. J Clin Exp Neuropsychol 32(10):1062–1067
Haehner A, Rodewald A, Gerber JC et al (2008) Correlation of olfactory function with changes in the volume of the human olfactory bulb. Arch Otolaryngol Head Neck Surg 134(6):621–624
Liu J, Ni D, Zhang Q (2008) Characteristics of olfactory event-related potentials in young adults with normal smell. Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 22(8):352–355
Rombaux P, Huart C, Collet S et al (2010) Presence of olfactory event-related potentials predicts recovery in patients with olfactory loss following upper respiratory tract infection. Laryngoscope 120(10):2115–2118
Rombaux P, Weitz H, Mouraux A et al (2006) Olfactory function assessed with orthonasal and retronasal testing, olfactory bulb volume, and chemosensory event-related potentials. Arch Otolaryngol Head Neck Surg 132(12):1346–1351
Stuck BA, Frey S, Freiburg C et al (2006) Chemosensory event-related potentials in relation to side of stimulation, age, sex, and stimulus concentration. Clin Neurophysiol 117(6):1367–1375
Liu J, Pinto JM, Yang L et al (2018) Evaluation of idiopathic olfactory loss with chemosensory event-related potentials and magnetic resonance imaging. Int Forum Allergy Rhinol 8(11):1315–1322
Horikiri K, Kikuta S, Kanaya K et al (2017) Intravenous olfactory test latency correlates with improvement in post-infectious olfactory dysfunction. Acta Otolaryngol 137(10):1083–1089
Kikuta S, Matsumoto Y, Kuboki A et al (2016) Longer latency of sensory response to intravenous odor injection predicts olfactory neural disorder. Sci Rep 6:35361
Rombaux P, Mouraux A, Keller T et al (2008) Trigeminal event-related potentials in patients with olfactory dysfunction. Rhinology 46(3):170–174
Ren Y, Yang L, Guo Y et al (2012) Intranasal trigeminal chemosensitivity in patients with postviral and post-traumatic olfactory dysfunction. Acta Otolaryngol 132(9):974–980
Funding
There are no financial disclosures of the authors. This study was supported by the Natural Science Foundation of China (81670903), Capital Health Research and Development of Special Fund (2018-2-2065), Beijing Hospitals Authority’ Mission Plan (SML20190601), Beijing Scholars Program (No. 051), and Capital Health Research and Development of Special Fund (2018-2-2065).
Author information
Authors and Affiliations
Contributions
YG: substantial contribution to the design of the manuscript, literature search, data analysis and interpretation. Preparing the main paper. DW: drafting the manuscript and revising it critically for important intellectual content. YW: Final approval of the manuscript. YG, ZS, LY, and JL collected the clinical data and followed up with the patients. All listed authors have approved the manuscript before submission, including the names and order of authors.
Corresponding author
Ethics declarations
Conflict of interest
All the authors declare that they have no conflict of interest.
Ethical approval
This study was approved by the Ethics Committee of Beijing Anzhen Hospital, Capital Medical University, and had been performed in accordance with the ethical standards as laid down in the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent
Informed consent was obtained from all individual participants included in the study.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Guo, Y., Wu, D., Sun, Z. et al. Prognostic value of olfactory evoked potentials in patients with post-infectious olfactory dysfunction. Eur Arch Otorhinolaryngol 278, 3839–3846 (2021). https://doi.org/10.1007/s00405-021-06683-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00405-021-06683-y
Keywords
- Post-infectious olfactory dysfunction
- Olfactory training
- Sniffin’ Sticks test
- Event-related potentials
- Predictors