Successful treatment of phantosmia with preservation of olfaction

Functional connectivity patterns in parosmia

OBJECTIVE

Parosmia is a qualitative olfactory dysfunction presenting as "distorted odor perception" in presence of an odor source. Aim of this study was to use resting state functional connectivity to gain more information on the alteration of olfactory processing at the level of the central nervous system level.

METHODS

A cross sectional study was performed in 145 patients with parosmia (age range 20-76 years; 90 women). Presence and degree of parosmia was diagnosed on the basis of standardized questionnaires. Participants also received olfactory testing using the "Sniffin' Sticks". Then they underwent resting state scans using a 3 T magnetic resonance imaging scanner while fixating on a cross.

RESULTS

Whole brain analyses revealed reduced functional connectivity in salience as well as executive control networks. Region of interest-based analyses also supported reduced functional connectivity measures between primary and secondary olfactory eloquent areas (temporal pole, supramarginal gyrus and right orbitofrontal cortex; dorso-lateral pre-frontal cortex and the right piriform cortex).

CONCLUSIONS

Participants with parosmia exhibited a reduced information flow between memory, decision making centers, and primary and secondary olfactory areas.

Olfactory Function and Olfactory Disorders

The sense of smell is important. This became especially clear to patients with infection-related olfactory loss during the SARS-CoV-2 pandemic. We react, for example, to the body odors of other humans. The sense of smell warns us of danger, and it allows us to perceive flavors when eating and drinking. In essence, this means quality of life. Therefore, anosmia must be taken seriously. Although olfactory receptor neurons are characterized by regenerative capacity, anosmia is relatively common with about 5 % of anosmic people in the general population. Olfactory disorders are classified according to their causes (e. g., infections of the upper respiratory tract, traumatic brain injury, chronic rhinosinusitis, age) with the resulting different therapeutic options and prognoses. Thorough history taking is therefore important. A wide variety of tools are available for diagnosis, ranging from short screening tests and detailed multidimensional test procedures to electrophysiological and imaging methods. Thus, quantitative olfactory disorders are easily assessable and traceable. For qualitative olfactory disorders such as parosmia, however, no objectifying diagnostic procedures are currently available. Therapeutic options for olfactory disorders are limited. Nevertheless, there are effective options consisting of olfactory training as well as various additive drug therapies. The consultation and the competent discussion with the patients are of major importance.

Parosmia and Phantosmia: Managing Quality Disorders

Purpose of Review

The purpose of this review was to summarize the current knowledge on parosmia and phantosmia and introduce support and treatment algorithms for the two qualitative olfactory disorders.

Recent Findings

Recent literature regarding parosmia has revealed that patients with the disorder are mainly triggered by certain substances, including thiols and pyrazines. In 2015, the existing "olfactory training" regimen was improved to more effectively treat post-infectious olfactory loss and was named "modified olfactory training" (MOT). It was also found in 2022 that MOT is also effective against COVID-19-induced parosmia.

Summary

Parosmia, the distortion of smells, is a symptom in qualitative olfactory disorders that severely affects patients' mental well-being and enjoyment of their everyday lives. The condition was first documented in 1895 and can affect up to 5% of the general population. Etiologies of parosmia include sinonasal diseases, viruses, surgeries, traumatic brain injury, neurological and psychiatric conditions, toxic chemicals, and medications. Parosmia has seen a surge in cases since the onset of the COVID-19 pandemic and is linked to changes in brain structure following an infection. The evaluation of the symptom is done using surveys, smell identification tests, fMRI, MRI, PET/CT, and gas chromatography. Treatment for parosmia can vary in duration, which makes it essential to focus not only on helping the patients regain normosmia, but also on supporting the patient through the recovery journey. Parosmia should not be confused with phantosmia, in which the distortion of smells occurs in the absence of olfactory stimuli. The etiology of phantosmia can vary from infections and traumatic brain injury to psychiatric disorders like schizophrenia. Unlike parosmia, the treatment of phantosmia is less straightforward, with an emphasis on determining the etiology and providing symptomatic relief.

Phantosmia May Predict Long-Term Measurable Olfactory Dysfunction After COVID-19

Objectives

Persistent olfactory dysfunction (OD) after 6 months caused by SARS‐CoV‐2 infection has been reported with a variable prevalence worldwide. This study aimed to determine the prevalence of long‐term OD and identify predisposing factors.

Methods

A prospective cohort study was conducted on 100 adults with COVID‐19. Olfactory function was assessed with the University of Pennsylvania Smell Identification Test and a symptom survey at the onset of disease and 30 days later. Patients with persistent quantitative OD at the second assessment were reevaluated after 1 year. Demographic variables, symptoms, and the degree of smell loss were analyzed.

Results

Participants included 100 patients. The mean age was 42.2 ± 15.6 years, 55 (55%) were female, and 56 (56%) were outpatients. Baseline smell loss was identified in 75/100 (75%) patients, decreasing to 39/95 (40%) after 1 month, and persisting in 29 patients after 1 year. Phantosmia at baseline was the only risk factor identified for persistent OD after 1 year (relative risk 2.51; 95% confidence interval 1.53–4.12; p < 0.001). Regardless of the outcome in smell function, a significant decline in olfaction was associated with the presence of phantosmia at 1 month (β = −12.39; 95% CI −19.82 to −4.95; p < 0.01).

Conclusions

SARS‐CoV‐2 (2019–2020 variants) produced a highly frequent OD that persisted in 29% of the patients after 1 year. The presence of phantosmia at baseline and 1 month was associated with a worse evolution, but phantosmia may interfere with the performance in an identification smell test. A longer follow‐up is required in these patients.

Level of Evidence

2 Laryngoscope, 2022

Riech- und Schmeckstörungen

Ziel der vorliegenden Übersicht ist es, einen Überblick über die Ätiologie und Diagnostik von Riech- und Schmeckstörungen zu geben. Da etwa 5 % der Allgemeinbevölkerung betroffen sind, ist es ein häufiges Krankheitsbild. Riechen und Schmecken erhielten v. a. zuletzt Aufmerksamkeit während des Aufkommens der SARS-CoV-2-Pandemie, wobei eine plötzlich aufgetretene Riech- und/oder Schmeckstörung zu den typischen Symptomen zählt. Daneben sind Riechstörungen in der Frühdiagnostik neurodegenerativer Erkrankungen von Bedeutung. Häufig zeigen Patienten mit Riechstörungen Zeichen einer Depression. Die Auswirkungen von Riech‑/Schmeckstörungen sind also umfangreich, die Therapiemöglichkeiten aktuell begrenzt. Nach einem Einblick in die Ätiologie werden Diagnostik und Therapiemöglichkeiten auf dem aktuellen Stand der Literatur erörtert. Auch zukunftsweisende Behandlungsvorstellungen, wie z. B. autologe Schleimhauttransplantationen oder olfaktorische Implantate, werden angesprochen.

Characterization, treatment modalities, and self-perceived improvement of post-COVID-19 phantosmia: a case series of eleven patients

Background: Loss of smell and taste is one of the early and sensitive symptoms of COVID-19 that usually improves over time. Post-COVID-19 phantosmia, a smell distorted sensation without the presence of odorants, has deleterious and long-lasting effects on the patient's quality of life. We aimed to present our experience with phantosmia. Case presentations: We report a description of a series of eleven cases (age of 29 ± 9 years, and 54.5% females) of post-COVID-19 phantosmia without any other comorbidity, and the effects of combined treatment modalities (olfactory training, nasal irrigation with budesonide and oral prednisolone) on self-perceived improvement in phantosmia. Conclusions: We postulate that the combined 10 days oral prednisolone, smell training, and nasal irrigation for three months improved post-COVID-19 phantosmia assessed as post vs. pre self-perceived improvement, although this was not aimed at as a treatment since it was not compared to untreated controls.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Therapies for Olfactory Dysfunction — an Update

Purpose of Review

Olfactory dysfunction is a prevalent condition affecting 5–15% of the general population, with significant impact on quality of life. This review summarizes the most recent and relevant literature in the treatment of olfactory dysfunction.

Recent Findings

Current evidence supports the short-term use of topical corticosteroids and systemic therapy. These treatments may occur in conjunction with olfactory training, which is well supported by the literature. While there are several additional treatments currently under investigation, meaningful conclusions are not yet able to be made regarding their efficacy.

Summary

The treatment of olfactory dysfunction is targeted at the suspected etiology when possible. After normal aging, chronic rhinosinusitis, post-infectious sequelae including as a result SARS-CoV-2 infection (COVID-19), and head trauma are the most common causes. Current evidence supports the short-term use of topical corticosteroids and systemic therapy. Several additional treatments are under investigation but recommendations for their use cannot currently be made.

Graphical abstract

[Olfactory and gustatory disorders]

Ziel der vorliegenden Übersicht ist es, einen Überblick über die Ätiologie und Diagnostik von Riech- und Schmeckstörungen zu geben. Da etwa 5 % der Allgemeinbevölkerung betroffen sind, ist es ein häufiges Krankheitsbild. Riechen und Schmecken erhielten v. a. zuletzt Aufmerksamkeit während des Aufkommens der SARS-CoV-2-Pandemie, wobei eine plötzlich aufgetretene Riech- und/oder Schmeckstörung zu den typischen Symptomen zählt. Daneben sind Riechstörungen in der Frühdiagnostik neurodegenerativer Erkrankungen von Bedeutung. Häufig zeigen Patienten mit Riechstörungen Zeichen einer Depression. Die Auswirkungen von Riech‑/Schmeckstörungen sind also umfangreich, die Therapiemöglichkeiten aktuell begrenzt. Nach einem Einblick in die Ätiologie werden Diagnostik und Therapiemöglichkeiten auf dem aktuellen Stand der Literatur erörtert. Auch zukunftsweisende Behandlungsvorstellungen, wie z. B. autologe Schleimhauttransplantationen oder olfaktorische Implantate, werden angesprochen.

Clinical Features of Parosmia Associated With COVID-19 Infection

Objective

To characterize the clinical features, risk factors, symptom time‐course, and quality of life implications for parosmia among coronavirus disease (COVID)‐related olfactory dysfunction patients.

Methods

Individuals with olfactory dysfunction associated with laboratory‐confirmed or clinically suspected COVID‐19 infection were recruited from otolaryngology and primary care practices over a period from August 2020 to March 2021. Participants completed olfactory dysfunction and quality of life surveys.

Results

A total of 148 (64.1%) of 231 respondents reported parosmia at some point. Parosmia developed within 1 week of any COVID‐19 symptom onset in 25.4% of respondents, but more than 1 month after symptom onset in 43.4% of respondents. Parosmia was associated with significantly better quantitative olfactory scores on Brief Smell Identification Test (8.7 vs. 7.5, P = .006), but demonstrated worse quality of life scores, including modified brief Questionnaire of Olfactory Dysfunction—Negative Statements and Sino‐Nasal Outcome Test‐22 scores (12.1 vs. 8.5, P < .001; 26.2 vs. 23.2, P = .113). Participants who developed parosmia at any point were significantly younger and less likely to have history of chronic sinusitis than those who did not develop parosmia (40.2 vs. 44.9 years, P = .007; 7.2% vs. 0.7%, P = .006).

Conclusion

COVID‐19‐associated olfactory dysfunction is frequently linked with development of parosmia, which often presents either at onset of smell loss or in a delayed fashion. Despite better quantitative olfactory scores, respondents with parosmia report decreased quality of life. A majority of respondents with persistent parosmia have sought treatment.

Level of Evidence

3 Laryngoscope, 132:633–639, 2022

Olfactory hallucinations in a population-based sample

Olfactory hallucinations referring to olfactory perceptions in the absence of chemical stimuli, occur in non-clinical and clinical populations. Few studies have investigated their prevalence in the general population and little is known about factors triggering and maintaining them such as substance use, severe life events, and mood. We analyzed self-report data from 2500 community dwelling Norwegians, aged 18-96 years, for occurrence of olfactory hallucinations and co-occurring hallucinations in other modalities (auditory, visual, tactile). Analyses included age, sex, self-reported symptoms of depression and anxiety, mental health status, and experience of severe life-events. The results show that 4.2% (95% CI 3.5-5.1%) reported having experienced olfactory hallucinations, and 56% of individuals experiencing olfactory hallucinations also reported these in combination with hallucinations in other modalities. Prevalence varied significantly in terms of age and sex, in that olfactory hallucinations were most frequently reported by young individuals and females. Self-reported symptoms of anxiety and experience of stressful life events were significantly associated with olfactory hallucinations, suggesting that experiencing olfactory hallucinations may negatively affect functioning and may increase the likelihood of developing psychopathology. Findings underline the need to continue to examine olfactory hallucinations albeit with a more comprehensive assessment in order to increase knowledge on this experience.

Prevalence and correlates of parosmia and phantosmia among smell disorders

Among those many individuals who experience a reduced odor sensitivity (hyposmia/anosmia), some individuals also have disorders that lead to odor distortion, such as parosmia (i.e. distorted odor with a known source), or odor phantoms (i.e. odor sensation without an odor source). We surveyed a large population with at least one olfactory disorder (N = 2031) and found that odor distortions were common (46%), with respondents reporting either parosmia (19%), phantosmia (11%), or both (16%). In comparison to respondents with hyposmia or anosmia, respondents with parosmia were more likely to be female, young, and suffering from post-viral olfactory loss (P < 0.001), while respondents with phantosmia were more likely to be middle-aged (P < 0.01) and experiencing symptoms caused by head trauma (P < 0.01). In addition, parosmia, compared to phantosmia or anosmia/hyposmia, was most prevalent 3 months to a year after olfactory symptom onset (P < 0.001), which coincides with the timeline of physiological recovery. Finally, we observed that the frequency and duration of distortions negatively affects the quality of life, with parosmia showing a higher range of severity than phantosmia (P < 0.001). Previous research often grouped these distortions together, but our results show that they have distinct patterns of demographics, medical history, and loss in quality of life.

Apparently Minor Head Trauma Can Lead to Anosmia: A Case Report

We report the case of a 49-year-old female patient who suffered from anosmia following an apparently mild head trauma when bumping into a door at her home. She reported no other accompanying symptoms after the injury that day. Olfactory function was completely lost, which was noted the day after the trauma. Gustatory function remained normal. Magnetic resonance imaging indicated lesions/bleeding in the right frontal lobe and in the area of the olfactory sulcus/bulb. The present case indicates that in case of apparently mild head trauma with anosmia, an MRI scan of the head should be performed because of suspect brain damage. This case also points to the deeper question how to gauge severity of head trauma.

Assessment of odor hedonic perception: the Sniffin' sticks parosmia test (SSParoT)

Qualitative olfactory dysfunction is characterized as distorted odor perception and can have a profound effect on quality of life of affected individuals. Parosmia and phantosmia represent the two main subgroups of qualitative impairment and are currently diagnosed based on patient history only. We have developed a test method which measures qualitative olfactory function based on the odors of the Sniffin’ Sticks Identification subtest. The newly developed test is called Sniffin’ Sticks Parosmia Test (SSParoT). SSParoT uses hedonic estimates of two oppositely valenced odors (pleasant and unpleasant) to assess hedonic range (HR) and hedonic direction (HD), which represent qualitative olfactory perception. HR is defined as the perceivable hedonic distance between two oppositely valenced odors, while HD serves as an indicator for overall hedonic perception of odors. This multicenter study enrolled a total of 162 normosmic subjects in four consecutive experiments. Cluster analysis was used to group odors from the 16-item Sniffin’ Sticks Identification test and 24-additional odors into clusters with distinct hedonic properties. Eleven odor pairs were found to be suitable for estimation of HR and HD. Analysis showed agreement between test–retest sessions for all odor pairs. SSparoT might emerge as a valuable tool to assess qualitative olfactory function in health and disease.

Diseases of the nasal cavity

Despite garnering minimal attention from the medical community overall, olfaction is indisputably critical in the manner in which we as humans interact with our surrounding environment. As the initial anatomical structure in the olfactory pathway, the nasal airway plays a crucial role in the transmission and perception of olfactory stimuli. The goal of this chapter is to provide a comprehensive overview of olfactory disturbances as it pertains to the sinonasal airway. This comprises an in-depth discussion of clinically relevant nasal olfactory anatomy and physiology, classification systems of olfactory disturbance, as well as the various etiologies and pathophysiologic mechanisms giving rise to this important disease entity. A systematic clinical approach to the diagnosis and clinical workup of olfactory disturbances is also provided in addition to an extensive review of the medical and surgical therapeutic modalities currently available.

Treatments for smell and taste disorders: A critical review

A key concern of both the patient and physician is whether treatment is available that will eliminate or quell a given chemosensory disturbance. In cases where obvious oral, nasal, or intracranial pathology is involved, rational straightforward approaches to treatment are often available. In cases where damage to the sensory pathways is secondary to chronic inflammatory disease, trauma, viral invasion, toxic exposure, or unknown causes, the direction for therapy is more challenging. Indeed, many chemosensory disorders, if present for any period of time, cannot be reversed, while others spontaneously remit without any therapeutic intervention. This review assesses the strengths and weaknesses of more than two dozen approaches to treatment that have been suggested for a wide range of taste and smell disorders.

Management of long-lasting phantosmia: a systematic review

BACKGROUND

Interest in the pathophysiology and management of phantom smells has increased rapidly over the last decade. A PubMed search for the term "phantosmia" demonstrated a near-doubling of articles published on phantosmia within the past 7 years. We aimed to systematically review the literature on the management of phantosmia.

METHODS

The PubMed, EMBASE, and Cochrane databases were searched for articles published since January 1990, using terms combined with pertinent Boolean search operators. We included articles evaluating management of phantosmia written in the English language, with original data and a minimum of 6 months of follow-up, on at least 2 patients and with well-defined and measurable outcomes.

RESULTS

A total of 2151 unique titles were returned upon the initial search. Of these, 146 abstracts were examined, yielding 7 articles meeting the inclusion criteria. All articles were predominantly level 4 evidence. One prospective level 3 study was included. The studies included a total of 96 patients, with follow-up ranging from 6 months to 11 years. Endpoints were primarily based on subjective patient responses. Management options included observation and medical and surgical therapy. Olfactory mucosa excision was the only surgical intervention studied, with short-term symptomatic improvement in 10 of 11 patients. Forty-one patients were treated medically, which included antipsychotic, antimigraine, and antiseizure medications, transcranial stimulation, and topical cocaine application.

CONCLUSION

Despite increasing interest in the treatment of phantosmia and reports of successful therapies, there remains a paucity of data and lack of consensus regarding optimal management of this difficult condition.

Phantosmia and Dysgeusia following Endoscopic Transcribriform Approaches to Olfactory Groove Meningiomas

The endoscopic, endonasal transcribriform approach (EETA) is an important technique used to directly access the anterior skull base and is increasingly being used in the management of olfactory groove meningiomas (OGMs). As this approach requires removal of the cribriform plate and olfactory epithelium en route to the tumor, patients are anosmic postoperatively. Here, we report the development of phantosmia and dysgeusia in two patients who underwent EETAs for OGMs, which has not yet been reported in the literature. We hypothesize that phantosmia and dysgeusia may result from aberrant neuronal signals or misinterpretation centrally from the remaining distal portions of the olfactory and taste pathways. Since EETAs are newer than traditional open craniotomy-based techniques, reporting these outcomes will be important to appropriately counsel patients preoperatively.

Olfactory Hallucinations without Clinical Motor Activity: A Comparison of Unirhinal with Birhinal Phantosmia

Olfactory hallucinations without subsequent myoclonic activity have not been well characterized or understood. Herein we describe, in a retrospective study, two major forms of olfactory hallucinations labeled phantosmias: one, unirhinal, the other, birhinal. To describe these disorders we performed several procedures to elucidate similarities and differences between these processes. From 1272, patients evaluated for taste and smell dysfunction at The Taste and Smell Clinic, Washington, DC with clinical history, neurological and otolaryngological examinations, evaluations of taste and smell function, EEG and neuroradiological studies 40 exhibited cyclic unirhinal phantosmia (CUP) usually without hyposmia whereas 88 exhibited non-cyclic birhinal phantosmia with associated symptomology (BPAS) with hyposmia. Patients with CUP developed phantosmia spontaneously or after laughing, coughing or shouting initially with spontaneous inhibition and subsequently with Valsalva maneuvers, sleep or nasal water inhalation; they had frequent EEG changes usually ipsilateral sharp waves. Patients with BPAS developed phantosmia secondary to several clinical events usually after hyposmia onset with few EEG changes; their phantosmia could not be initiated or inhibited by any physiological maneuver. CUP is uncommonly encountered and represents a newly defined clinical syndrome. BPAS is commonly encountered, has been observed previously but has not been clearly defined. Mechanisms responsible for phantosmia in each group were related to decreased gamma-aminobutyric acid (GABA) activity in specific brain regions. Treatment which activated brain GABA inhibited phantosmia in both groups.

Hidden consequences of olfactory dysfunction: a patient report series

BACKGROUND

The negative consequences of olfactory dysfunction for the quality of life are not widely appreciated and the condition is therefore often ignored or trivialized.

METHODS

1,000 patients with olfactory dysfunction participated in an online study by submitting accounts of their subjective experiences of how they have been affected by their condition. In addition, they were given the chance to answer 43 specific questions about the consequences of their olfactory dysfunction.

RESULTS

Although there are less practical problems associated with impaired or distorted odor perception than with impairments in visual or auditory perception, many affected individuals report experiencing olfactory dysfunction as a debilitating condition. Smell loss-induced social isolation and smell loss-induced anhedonia can severely affect quality of life.

CONCLUSIONS

Olfactory dysfunction is a serious condition for those affected by it and it deserves more attention from doctors who treat affected patients as well as from scientist who research treatment options.

Phantosmia during radiation therapy: a report of 2 cases

Phantosmia is an infrequently reported and poorly understood qualitative olfactory disorder characterized by the perception of a frequently unpleasant odor in the absence of an odorant stimulus. Peripheral phantosmia is hypothesized to involve abnormally active olfactory receptor neurons while central phantosmia is theorized to be the result of hyperactive neurons in the cortex. The authors present a case report that describes 2 patients with incomparable tumors and radiation fields who both experienced phantosmia featuring a halitosis-like odor during their courses of radiation therapy. Both the 6-year-old with diffuse intrinsic pontine glioma and the 15-year-old with World Health Organization grade II-III astrocytoma in the bifrontal lobes experienced significant distress and decreased quality of life during treatment because of the phantosmia, which resolved after completion of radiation therapy. To the best of the authors' knowledge, these are the first descriptions of phantosmia during focal or whole-brain radiation therapy.

Distorted olfactory perception: a systematic review

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 classified 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.

Olfaction in dentistry

Practitioners of oral medicine frequently encounter patients with complaints of taste disturbance. While some such complaints represent pathological processes specific to the gustatory system, per se, this is rarely the case. Unless taste-bud mediated qualities such as sweet, sour, bitter, salty, umami, chalky, or metallic are involved, 'taste' dysfunction inevitably reflects damage to the sense of smell. Such 'taste' sensations as chicken, chocolate, coffee, raspberry, steak sauce, pizza, and hamburger are dependent upon stimulation of the olfactory receptors via the nasopharynx during deglutition. In this paper, we briefly review the anatomy, physiology, and pathophysiology of the olfactory system, along with means for clinically assessing its function. The prevalence, etiology, and nature of olfactory disorders commonly encountered in the dental clinic are addressed, along with approaches to therapy and patient management.

Olfaction and olfactory epithelium in mice treated with zinc gluconate

OBJECTIVE

We assessed whether a nasal spray containing zinc gluconate (ZG) compromises the integrity of olfactory epithelium and olfactory function.

METHODS

Axonal transport of horseradish peroxidase from olfactory epithelium to the olfactory bulb was studied in 2- to 21-day survival mice given intranasal injections of 2, 8, or 50 microL of ZG (approximately 4, 15, and 94 times the equivalent recommended human dose). Other similarly treated mice were tested using precision olfactometry to detect and discriminate odors.

RESULTS

Anatomic changes were graded as a function of dose and survival time. Two microliter injections had no discernable effect. while the 50 microL volume produced substantial deafferentation of input to the olfactory bulb in short-survival cases. Nearly complete restitution of input occurred within 3 weeks. At each volume and survival time, zinc sulfate (ZS) had a greater effect. Behaviorally, 2 microL and 8 microL ZG-treated mice and those given multiple injections of 2 microL ZG performed as well as controls, whereas those given 50 microL were hyposmic but not anosmic. ZS-treated mice performed more poorly, and those injected with 50 microL were anosmic for the first 8 to 10 test days.

CONCLUSIONS

A massive dose of a ZG nasal spray did cause a transient disruption of the olfactory epithelium and compromised olfaction. More moderate volumes, even those far in excess of a recommended dose, were largely without effect on odor detection and discrimination tasks. These outcomes fail to support the claims from recent clinical case reports that use of a ZG-containing nasal spray can produce anosmia.

Diagnosis and management of olfactory disorders: survey of UK-based consultants and literature review

Background:

The diagnosis and management of olfactory disorders is an often neglected topic in otolaryngology. This article evaluates current clinical practice within the United Kingdom, and provides a literature-based review of the diagnosis, management and prognosis of olfactory pathology.

Design:

A questionnaire was sent to consultant and associate specialist members of the British Association of Otolaryngologists and Head and Neck Surgeons. The responses were documented to gain an impression of how olfactory disorders are managed in the United Kingdom. The literature relating to olfactory dysfunction was then evaluated and the findings summarised.

Conclusions:

Management of olfactory pathology varies across the United Kingdom. The literature suggests that chemosensory testing is optimal and that both forced-choice and threshold testing should be applied if objective evaluation is required. Imaging can be of value but the appropriate technique should be used. Olfactory function can recover following head injury, viral infection and chronic sinonasal disease, although varying degrees of dysfunction are likely to persist. There is a role for the use of corticosteroids, particularly when administered systemically. More research is needed to establish the appropriate dose and length of treatment.

Basic and clinical aspects of olfaction

Disturbances of olfaction are a common occurrence in many neurological and neurosurgical patients and their correct diagnosis might be helpful in management and enhancement of quality of life. However, olfaction is seldom checked in most neurosurgical units and the "smell bottles" are often either absent or out of date. This chapter reviews systematically recent advances in our understanding of the anatomy, physiology (olfactory coding) and measurement of olfactory function in the human. The causes and symptoms of smell disorders, risk of damage to the olfactory system by various surgical procedures and, finally, the natural history of recovery and treatment of smell disorders, for example after trauma, are discussed.

Smell and taste disorders

Disorders of taste and smell can present a challenge to the facial plastic surgeon. Obtaining a detailed history and examination is the key to the diagnosis and work-up of olfactory and gustatory dysfunction. Easy-to-administer tests are available for olfactory evaluation(University of Pennsylvania Smell Identification Test) and gustatory (taste sticks, tasting tablets) evaluation. The prognosis and management of olfactory and gustatory disease depend on its etiology. Despite ongoing research, the treatment of the disorders of smell and taste is limited.

Clinical presentation of qualitative olfactory dysfunction

Many patients with olfactory dysfunction not only experience quantitative reduction of olfactory function, but also suffer from distorted olfactory sensations. This qualitative dysfunction is referred to as parosmia (also called "troposmia") or phantosmia, with the major difference that distorted olfactory sensations are experienced in the presence or absence of an odor, respectively. Our clinical observations corroborate the literature in terms of a general underestimation of the incidence of olfactory distortions. Based on selected cases we try to show that olfactory distortions exhibit a large variance in their clinical appearance. Further, emphasis is placed on the fact that only a detailed and directed history of the patient can provide cues to the correct diagnosis.

The management of idiopathic olfactory hallucinations: a study of two patients

OBJECTIVES/HYPOTHESIS

Idiopathic olfactory hallucination is a rare condition. We report two cases of idiopathic olfactory hallucination and a review of the literature that relates to this condition.

STUDY DESIGN

A retrospective case study of two patients with idiopathic olfactory hallucination.

METHODS

Records of two patients were retrospectively reviewed.

RESULTS

The diagnosis of idiopathic olfactory hallucination was confirmed after excluding any intranasal disease or any central nervous system disorder discernible by an electroencephalogram and magnetic resonance imaging. Both patients were successfully treated with sodium valproate. One patient stopped taking sodium valproate because of side effects, only for the symptoms to return, but these were then controlled by phenytoin sodium. The mean patient follow-up time was 3 years 5 months.

CONCLUSIONS

The symptoms of some cases of idiopathic olfactory hallucination may be controlled by sodium valproate or phenytoin sodium. We hypothesize that this disorder may be a central phenomenon attributable to reverberating circuits.

Olfaction - Quantification and management

Patients with olfactory disorders are often referred to the otolaryngologist for assessment and treatment. Karely, however, is the otolaryngologist prepared to provide such services. In a previous paper in this journal, we described the basic anatomy and physiology of the olfactory system. Additionally, we listed a standardized nomenclature for classifying olfactory disturbances, and reviewed means for clinically assessing such disorders. In this paper, we provide a more detailed protocol for evaluating patients with loss of smell, incorporating sensory, imaging, and medical approaches employed at the Smell and laste Center of the University of Pennsylvania, USA. Examples of common syndromes encountered in everyday practice are deicribed.

Physiologically initiated and inhibited phantosmia: cyclic unirhinal, episodic, recurrent phantosmia revealed by brain fMRI

PURPOSE

Our goal was to use functional magnetic resonance imaging (fMRI) to demonstrate brain activation in patients with unirhinal, episodic, recurrent phantosmia who induced their phantosmia by coughing, sneezing, laughing or vigorous nasal inhalation and expiration, and inhibited it by sleep or performance of a Valsalva type maneuver.

METHODS

Three patients with unirhinal phantosmia without change in taste or smell acuity were studied by fast low angle shot (FLASH) MRI and by echo planar imaging (EPI). Brain activation was measured following memory of two tastants (salt, sweet), memory of two odorants (banana and peppermint), actual smell of three odors (amyl acetate, menthone, pyridine), memory of phantosmia (and phantageusia, where applicable), phantosmia initiated spontaneously or by vigorous nasal inhalation and exhalation, phantosmia after inhibition by Valsalva, and these stimuli before and after treatment with the neuroleptic thioridazine. Activation images were derived using correlation analysis and ratios of areas of brain activated to total brain areas were calculated. Total activated pixel cluster counts were also used to quantitative total and regional brain activation.

RESULTS

Sensory-specific brain activation was present in each section in each patient following memory of tastants and odorants, actual smell of each odor and memory, and initiation of and inhibition of phantosmia. Activation to odor memory after phantosmia initiation was very robust, whereas after phantosmia inhibition it was similar to that in normal subjects. Brain activation to unirhinal phantosmia was bihemispheric, independent of whether it was left or right sided or patient handedness. While phantosmia memory (in the absence of initiated phantosmia) produced extremely robust brain activation, after initiation and inhibition of phantosmia apparent brain activation decreased. These changes need to be related to shifting state of baseline brain activation and should be interpreted to reflect increased rather than decreased brain activation over that of phantosmia memory alone. Treatment with thioridazine inhibited brain activation to all stimuli including phantosmia and phantageusia memory, as it did previously in patients with birhinal phantosmia.

CONCLUSIONS

1) Unirhinal phantosmia can be demonstrated by brain fMRI as can birhinal phantosmia; 2) unirhinal phantosmia can be initiated and inhibited by physiological maneuvers reflected by changes in fMRI brain activation; 3) fMRI brain activation of unirhinal phantosmia is bihemispheric and independent of peripheral side of phantosmia or patient handedness; 4) anterior frontal brain region plays a significant role in both phantosmia initiation and inhibition as, to some extent, do temporal brain regions; 5) activation of brain GABAergic systems appears to play a role in inhibition of unirhinal phantosmia; and 6) unirhinal phantosmia, similar to birhinal phantosmia, may reflect a type of maladaptive brain plasticity similar to that hypothesized to be responsible for phantom limb pain.

Taste and smell phantoms revealed by brain functional MRI (fMRI)

PURPOSE

Our goal was to demonstrate the appearance of phantom tastes and smells (phantageusia and phantosmia, respectively) by use of functional MRI (fMRI) of the brain and to demonstrate the efficacy of drug treatment that inhibited both the subjective presence of these phantoms and the fMRI brain activation initiated by these phantoms.

METHOD

Multislice FLASH MR or echo planar MR brain scans were obtained in two patients with phantageusia and phantosmia in response to memory of two tastants (salt and sweet); memory of two odors (banana and peppermint); actual smell of amyl acetate, menthone, and pyridine; and memory of phantom tastes and smells before and after treatment with thioridazine and haloperidol. Activation images were derived using correlation analysis, and ratios of brain area activated to total brain area were obtained.

RESULTS

Prior to treatment, both patients experienced persistent birhinal and global oral obnoxious tastes and smells in the absence of any external stimulus. The fMRI response to memory of phantoms was activation in sensory-specific brain regions for taste and smell, respectively. fMRI activation was greater than for memory of any tastant or odorant or for actual smell of any odor. After treatment with thioridazine or haloperidol, which successfully inhibited each phantom in each patient, fMRI response to phantom memory was significantly inhibited and was significantly lower than for memory of any tastant or odorant or actual smell of any odorant.

CONCLUSION

These results demonstrate that (a) phantom taste and smell can be revealed by fMRI brain activation, (b) brain activation in response to taste and smell phantoms is localized in sensory-specific brain regions for taste and smell, respectively, (c) brain activation in response to memory of each phantom initiated the greatest degree of activation we had previously measured, and (d) treatment with thioridazine or haloperidol inhibited both the presence of each phantom and its associated fMRI brain activation. This is the first study in which phantom tastes and smells have been demonstrated by an objective technique and treatment that inhibited the phantoms was characterized by objective inhibition of fMRI activation. These two patients represent a relatively common group that may be classified as having primary phantageusia and phantosmia distinct from those with phantoms or auras secondary to neurological, migrainous, psychiatric, or other causes.

Congenital anosmia

Congenital anosmia is well described in conjunction with various sexual and other developmental abnormalities and has been reported to run in families. Congenital anosmia occurring as an isolated defect in a single family member is extremely rare, and tends to present late. We describe a case of a five year old girl with congenital anosmia and we outline the investigations which should be undertaken in such cases.

Prevalence and assessment of qualitative olfactory dysfunction in different age groups

The prevalence of parosmia and phantosmia among 363 chemosensory and nasal/sinus patients was studied, as was the accuracy with which our clinical questionnaire could assess these dysfunctions. We then investigated whether patients with parosmia or phantosmia, matched for odor intensity, perform poorer on odor identification than do patients with no dysosmia. More than 40% of the study group evidenced either parosmia (18.7%) and/or phantosmia (25.6%), a finding that suggests that more attention should be paid by the medical practitioner in addressing qualitative olfactory dysfunction. Furthermore, it appears that assessment of these dysfunctions may aid in differential diagnosis, and that questionnaires can be used with reasonable validity irrespective of the patient's age. Finally, the results imply that parosmia may be reflected in a discrepancy between odor identification and detection.