xRead - Olfactory Disorders (September 2023)

Acta Oto-Laryngologica, 2012; 132: S27 – S31

REVIEW ARTICLE

Distorted olfactory perception: A systematic review

SEOK-CHAN HONG 1 , ERIC H. HOLBROOK 2 , DONALD A. LEOPOLD 3 & THOMAS HUMMEL 4

1 Department of Otorhinolaryngology, Konkuk University Hospital, Seoul, Korea, 2 Department of Otolaryngology, Massachusetts Eye and Ear In fi rmary, Harvard Medical School, Boston, MA, USA, 3 Department of Otolaryngology-Head and Neck Surgery, University of Nebraska Medical Center, Omaha, NE, USA and 4 Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany

Abstract The sense of smell provides people with valuable input from the chemical environment around them. The human sense of smell generally fails in three ways; one is an intensity reduction and the other two are the quality of changes. Smell disorders can be classi fi ed into central or peripheral depending on their origin. Central causes can be related to an area of hyper functioning brain cells generating this odor perception, thus olfactory distortions have also been observed with epilepsy and migraine. In this paper, we present a review of the current clinical understanding of olfactory distortions and discuss how they can be evaluated and therapies to treat this debilitating condition. Keywords: Olfactory nerve diseases, olfaction disorders, smell

Introduction

repeatedly being reminded of the problem. This can cause deleterious effects on fl avor and quality of life, resulting in weight loss and nutritional problems. In the analysis of a series of 56 patients with parosmia, 31 patients (55.4%) viewed their olfactory alteration as severely affecting their quality of life [2]. The terms used to describe olfactory distortions have been confusing in the past, but generally the following terms are now used. ‘ Dysosmia ’ canbeused to describe any reduction or distortion of the sense of smell. ‘ Phantosmia ’ (lasting longer than a few seconds) and ‘ olfactory hallucination ’ (lasting only a few seconds) describe the perceived distortion (usu ally unpleasant) when there is no odorant stimulus present. ‘ Cacosmia ’ is the perception of a bad smell with or without an odorant stimulus. ‘ Euosmia ’ has been described as a pleasant parosmia to selected odorants [3]. Both ‘ cacosmia ’ and ‘ euosmia ’ can be summarized under the term ‘ parosmia. ’ Smell distortions can be classi fi ed into central or peripheral depending on their respective origins.

The sense of smell provides people with valuable input from the chemical environment around them. When this input is distorted, disability and decreased quality of life are reported [1]. The purpose of this paper is to present a review of the current clinical understanding of olfactory distortions, how they can be evaluated, and therapies to treat this debilitating condition. The human sense of smell generally fails in one of three ways. One is an intensity reduction resulting in decreased olfactory sensitivity (hyposmia or anosmia). The other two are quality changes with a distortion of the perceived odor. One type of distortion occurs when inhaled odorants do not have the same smell or odor as remembered (parosmia). The other type of distortion is the perception of an odor (usually unpleasant) when there is no odorant in the environ ment (phantosmia, hallucination). These distortions are usually much more disruptive to a person ’ s life than a simple loss, because those who are affected are

Correspondence: Seok-Chan Hong MD, Department of Otorhinolaryngology, Konkuk University Hospital, Hwayang-dong, Gwangjin-gu, Seoul, 4-12, Korea. Tel: +82 10 4250 9875. Fax: +82 2 2030 5299. E-mail: 20050692@kuh.ac.kr

(Received 11 October 2011; accepted 17 January 2012) ISSN 0001-6489 print/ISSN 1651-2251 online 2012 Informa Healthcare DOI: 10.3109/00016489.2012.659759