The Laryngoscope C 2015 The American Laryngological, V

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Case Report

Rapidly Fluctuating Anosmia: A Clinical Sign for Unilateral Smell Impairment Simona Negoias, MD; Hergen Friedrich, MD; Marco D. Caversaccio, MD; Basile N. Landis, MD Reports about fluctuating olfactory deficits are rare, as are reports of unilateral olfactory loss. We present a case of unilateral anosmia with contralateral normosmia, presenting as rapidly fluctuating anosmia. The olfactory fluctuation occurred in sync with the average nasal cycle duration. Examination after nasal decongestion, formal smell testing, and imaging revealed unilateral, left-sided anosmia of sinonasal cause, with right-sided normosmia. We hypothesize that the nasal cycle induced transient anosmia when blocking the normosmic side. Fluctuating olfactory deficits might hide a unilateral olfactory loss and require additional unilateral testing and thorough workup. Key Words: Smell disorders, sinonasal, unilateral anosmia, fluctuating olfactory loss, nasal cycle. Laryngoscope, 126:E57–E59, 2016

INTRODUCTION

CASE REPORT

The human olfactory pathway projects ipsilaterally to the brain, and central processing of its information is initially also restricted to the same hemisphere. Later processing includes bilateral cortical activation.1 The clinical consequence of this ipsilateral wiring is that unilateral olfactory deficits remain asymptomatic and thus unnoticed. Measured olfactory function mostly reflects the best side when tested bilaterally.2 Very few reports are published about unilateral smell impairments, and most are about distorted olfactory function rather than reduced or absent olfaction.3 However, recent literature suggests that unilateral smell impairment seems to be more prevalent and potentially more meaningful than previously thought.4,5 Unilateral olfactory impairment was proposed as a negative prognostic factor for the development of an overall olfactory deficit.6 More accurate detection of unilateral olfactory deficits would thus be clinically relevant. Based on observations from this case, we suggest that a rapid alternation between normal and altered smell function may be one clinical sign of unilateral olfactory impairment.

A 53-year-old woman was referred to our smell and taste clinic because of fluctuating smell impairment. She reported alternating episodes of anosmia and normosmia, lasting several hours. The change from one state to the other was quick and, within 20 to 30 minutes, a complete olfactory loss would be present for 3 to 5 hours, then followed by total recovery, which lasted approximately the same time. It had started 8 months prior to presentation, with no clear identifiable or preceding cause. The changes could not be triggered or reversed by the patient. Olfactory distortions were not present. As for background history, the woman had stopped smoking for 2 years and was allergic to kiwi fruit. No head trauma or upper respiratory tract infection was reported before the onset of the symptoms. She described her nasal patency as normal, and there were no other symptoms of chronic or acute recurrent rhinosinusitis or rhinitis. Clinical examination showed a slight septal deviation to the right, but both nasal cavities were otherwise patent, with no turbinate edema or polyposis. Endoscopy of the olfactory clefts showed a patent right side and narrowed, slightly congested left side. Olfactory testing was performed separately for each side using the Sniffin’ Sticks test battery following a standardized procedure.7 Local nasal decongestion was applied before testing odor threshold, odor discrimination and odor identification (TDI). The sum of the three individual tests builds the overall composite olfactory score (TDI score) ranging from zero to maximal 48 points. Normative data published elsewhere7 allow for a classification into anosmia (less than 16 points), hyposmia (between 16 and 30 points), or normosmia (above 30.5 points). Testing revealed a right-sided normosmia (TDI 5 35.25 points) and a left-sided anosmia (TDI 5 9 points).

From the Department of Otorhinolaryngology–Head and Neck Surgery (S.N., H.F., M.D.C., B.N.L.), Bern University Hospital, Bern, Switzerland; Rhinology-Olfactology Unit, Department of Otorhinolaryngology–Head and Neck Surgery (B.N.L.), University Hospital of Geneva Medical School, Geneva, Switzerland. Editor’s Note: This Manuscript was accepted for publication June 9, 2015. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Simona Negoias, MD, Bern University Hospital, Department of Otorhinolaryngology–Head and Neck Surgery, Inselspital, Freiburgstrasse 4, 3010 Bern, Switzerland. E-mail: [email protected] DOI: 10.1002/lary.25476

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Fig. 1. Consecutive slices of the coronal computed tomography (CT) of the present case. Partial opacities of the ethmoid cells and olfactory clefts indicate signs of sinonasal inflammation. The CT alone does not indicate clearly a unilateral olfactory deficit, which is suggested by the history and the psychophysical tests.

Computed tomography (CT) of the paranasal sinuses showed partial opacity of the ethmoid sinuses and the olfactory cleft on both sides (Fig. 1). Magnetic resonance imaging was normal. Based on symptoms and imaging, we concluded that the patient had clear signs of chronic rhinosinusitis. Endoscopy and olfactory testing (but not CT findings) suggested that the left side was more affected. As the symptoms alternated with a similar rhythm to the average nasal cycle,8 we assumed the latter to be a contributing factor to the unilateral olfactory anosmia and the factor most likely to be responsible for the rapidly changing symptoms. A 5-day treatment of oral steroids (prednisolone 50 mg) followed by a topical application of steroid drops (fluticasone vials; one vial per nostril twice a day and praying-to-Mecca position) for 3 weeks were given. The symptoms resolved and control olfactory testing showed that the left-side anosmia had recovered (TDI 5 31.25). Endoscopy showed an open and accessible olfactory cleft on both sides. Topical steroid drops were discontinued after 6 further weeks, and follow-up for a year showed no symptom recurrence.

DISCUSSION The present case suggests that rapidly fluctuating smell impairment is a clinical sign of unilateral olfactory pathologies. Fluctuating olfactory performance is probably more prevalent than reported in the literature. We only found one study systematically investigating this symptom, which clearly showed that fluctuation is mostly related to a sinonasal origin of the olfactory impairment.9 Rapid fluctuations, such as hourly or daily Laryngoscope 126: February 2016

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changes in olfactory function, have not yet been reported. We believe this symptom is probably more prevalent than is currently recognized, but is either overlooked by clinicians or under-reported by patients.4 The nasal cycle, which changes the state of congestion of the nasal mucosa in an individually variable but rhythmic manner every 3 to 6 hours,8,10 has been demonstrated to change olfactory perception between both nostrils in healthy individuals in a subtle way.11 At least two-thirds of the population seem to have a nasal cycle, but there are subjects without any major nasal volume changes over time.10 Rough olfactory function does not change dramatically with the nasal cycle.10 However, certain areas of the nasal cavity, such as the upper anterior segment, are significantly related to olfactory function.12 Thus, preexisting congestion in these areas together with a marked nasal cycle in a given subject might then be sufficient to influence olfactory function to an extent that it becomes clinically relevant and recognized by the patient. This is the most likely explanation for the present observation. However, the biological meaning and the impact of the nasal cycle upon olfactory perception is not yet clear. However, we believe this case clearly shows that the nasal cycle can modify olfactory perception, even when there is no major effect on nasal patency; our patient did not report any nasal obstruction when anosmia occurred. Unilateral olfactory testing is not part of the clinical routine in most specialized clinics worldwide, probably due to the time needed to perform the test. Bilateral testing mostly reflects the olfactory function of the best side, and thus unilateral deficits remain hidden if the Negoias et al.: Fluctuating Anosmia

opposite side shows normal function. Clinically, unilateral deficits rarely seem to cause symptomatic hyposmia. However, recent work showed that unilateral olfactory impairment or strongly asymmetric olfactory function heralds future overall bilateral olfactory impairment.6 Global olfactory deficits show a robust association to morbidity in the elderly and have been identified as potential marker of general health state in this population.13 As a consequence of these two recent findings, it becomes obvious that detecting unilateral olfactory impairments could give an earlier insight into the role of olfactory function in relation to mortality, morbidity, and global health state. If the present case was tested bilaterally only, the olfactory score would have been interpreted as normosmia, which would be in contrast to the patient’s complaints. With the present clinical case, we would like to first emphasize the importance of unilateral testing of olfactory function and, moreover, underline that even subtle patient complaints about a fluctuating sense of smell may suggest a unilateral olfactory problem. Active questioning regarding such fluctuation, especially rapid changes, need to be included in the patient’s history. This case also clearly shows that olfactory problems cannot be explained solely by imaging, endoscopy, or smell tests alone. A patient’s history is crucial and gives valuable indicators about how and what kind of tests need to be done. We feel that fluctuation of olfactory function is a crucial and valuable symptom, which is frequently neglected. It should be directly asked about in the history and, if present, should alert physicians to the need for a thorough workup to diagnose the cause of a unilateral smell impairment.

CONCLUSION Simple clinical symptoms, such as olfactory fluctuation, could point toward a sinonasal cause of smell

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impairment. An alternating and rapid change in olfactory function suggests unilateral olfactory pathology. These elements should be carefully inquired about during a patient’s history. We strongly emphasize the need to actively ask about alternating and lateralized olfactory impairment.

Acknowledgments The authors thank Dr. Nicholas Stow for the careful and critical reading of the manuscript.

BIBLIOGRAPHY 1. Lascano AM, Hummel T, Lacroix JS, Landis BN, Michel CM. Spatiotemporal dynamics of olfactory processing in the human brain: an event-related source imaging study. Neuroscience 2010;167:700–708. 2. Frasnelli J, Livermore A, Soiffer A, Hummel T. Comparison of lateralized and binasal olfactory thresholds. Rhinology 2002;40:129–134. 3. Erskine SE, Schelenz S, Philpott CM. Unilateral cacosmia: a presentation of maxillary fungal infestation. BMJ Case Rep 2013;2013. 4. Gudziol V, Hummel C, Negoias S, Ishimaru T, Hummel T. Lateralized differences in olfactory function. Laryngoscope 2007;117:808–811. 5. Welge-Lussen A, Gudziol V, Wolfensberger M, Hummel T. Olfactory testing in clinical settings - is there additional benefit from unilateral testing? Rhinology 2010;48:156–159. 6. Gudziol V, Paech I, Hummel T. Unilateral reduced sense of smell is an early indicator for global olfactory loss. J Neurol 2010;257:959–963. 7. Hummel T, Kobal G, Gudziol H, Mackay-Sim A. Normative data for the "Sniffin’ Sticks" including tests of odor identification, odor discrimination, and olfactory thresholds: an upgrade based on a group of more than 3,000 subjects. Eur Arch Otorhinolaryngol 2007;264:237–243. 8. Mirza N, Kroger H, Doty RL. Influence of age on the ’nasal cycle’. Laryngoscope 1997;107:62–66. 9. Apter AJ, Gent JF, Frank ME. Fluctuating olfactory sensitivity and distorted odor perception in allergic rhinitis. Arch Otolaryngol Head Neck Surg 1999;125:1005–1010. 10. Abolmaali N, Kantchew A, Hummel T. The nasal cycle: assessment using MR imaging. Chemosens Percept 2013;6:148–153. 11. Sobel N, Khan RM, Saltman A, Sullivan EV, Gabrieli JD. The world smells different to each nostril. Nature 1999;402:35. 12. Damm M, Vent J, Schmidt M, et al. Intranasal volume and olfactory function. Chem Senses 2002;27:831–839. 13. Pinto JM, Wroblewski KE, Kern DW, Schumm LP, McClintock MK. Olfactory dysfunction predicts 5-year mortality in older adults. PLoS One 2014;9:e107541.

Negoias et al.: Fluctuating Anosmia

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Rapidly fluctuating anosmia: A clinical sign for unilateral smell impairment.

Reports about fluctuating olfactory deficits are rare, as are reports of unilateral olfactory loss. We present a case of unilateral anosmia with contr...
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