Clinical presentation of qualitative olfactory dysfunction

Gray matter alterations in parosmia

Parosmia is a common olfactory disorder. In this condition, odors are perceived in a different quality than usual. This distorted olfactory percept is typically reported to be unpleasant. Little is known about the pathophysiology of this phenomenon. Previous studies demonstrated smaller volumes of the olfactory bulbs in patients with parosmia compared to subjects without parosmia. In order to investigate structural brain alterations in areas beyond the olfactory bulb, in the current study voxel-based morphometry was applied. A group of 22 parosmic patients was compared with control subjects matched for age- and sex, who exhibited a similar performance in olfactory tests. Performing a whole brain analysis, we found profound gray matter volume loss in the left anterior insula in parosmic patients. In an additional volume of interest analysis including primary and secondary olfactory areas, we also found volume loss in the right anterior insula, the anterior cingulate cortex, the hippocampus bilaterally, and the left medial orbitofrontal cortex. Many of these areas are critically involved in olfactory quality discrimination and odor memory. The present results indicate that reduced gray matter volume in brain regions supporting odor discrimination and memory is related to disturbed olfactory sensation in parosmia.

Evaluating the clinical usefulness of structured questions in parosmia assessment

OBJECTIVES/HYPOTHESIS

Parosmia and phantosmia relate to distorted odor perceptions. Little is known about their clinical significance. Measuring phantosmia and parosmia is still not possible. Today, assessment of parosmia or phantosmia relies mainly upon the patient's interview and the physician's experience. Therefore, we investigated the clinical usefulness of four structured questions in comparison to the patient's history regarding their accuracy in terms of the presence of odor distortions.

STUDY DESIGN

Tertiary care center outpatient clinic analyses.

METHODS

Responses from 193 patients were analyzed. All patients underwent full olfactory work-up (ear, nose, and throat examination, Sniffin' Sticks testing, structural brain imaging) and filled in a questionnaire with four parosmia questions and six questions regarding characteristics and severity of the parosmia. These responses formed the bases of a numerical parosmia score.

RESULTS

Patients with parosmia showed significantly lower parosmia scores (P <.001) when compared to either patients with phantosmia or patients without odor distortions. Two questions could be identified that showed a high association to the presence or absence of parosmia.

CONCLUSIONS

The present results confirm reports on the high frequency of parosmia and phantosmia among patients suffering from olfactory disorders. A parosmia score could be established that distinguishes between patients with or without odor distortions. The score provides valuable information regarding the presence or absence of parosmia, thus helping the physician during the patient's evaluation.

Phantom rhinitis

Sensitivity to strong odors has a broad differential diagnosis. A presentation is made of a 60-year-old man with lifelong mild allergic rhinitis and a superimposed 4-year history of sensitivity to smells. He had no response to medical treatments or allergic immunotherapy. His physical examination was unremarkable. After obtaining a detailed history, a definitive imaging study was performed and the patient underwent corrective treatment for his potentially life-threatening disorder. A detailed differential and strong clinical history is sometimes required to uncover the etiology of non-allergic rhinitis. Overwhelming sensations of strong odors may be a sign of a more serious condition and require investigation. This presentation discusses the differential diagnosis and suggested evaluation for patients with abnormalities in olfaction.

Olfactory performance before and after lung transplantation: quantitative assessment and impact on quality of life

BACKGROUND

Although olfactory function significantly impacts quality of life (QoL) and factors that potentially interfere with the sense of smell are numerous in solid-organ recipients, no respective data exist for this population. In this study we investigate the olfactory function, QoL, and the accuracy of subjectively perceived olfactory dysfunction.

METHODS

Olfactory performance was assessed with the aid of a validated test battery (Sniffin' Sticks) in 70 randomly selected lung transplant recipients and 22 patients on the lung transplant waiting list. In addition to assess QoL, the Questions on Life Satisfaction Module (FLZ(M)) and the Hospital Anxiety Depression Scale (HADS) were used.

RESULTS

Waiting list patients and lung transplant recipients did not show differences in terms of demographic data and olfactory performance. Compared with a normative population, patients <55 years of age had a significantly lower olfactory performance both before and after lung transplantation. Scores for general life satisfaction, health life satisfaction, and depression were significantly better in lung transplant recipients. In the multivariate analysis, better olfactory performance was significantly associated with better QoL before and after lung transplantation. Self-estimation of olfactory performance had a sensitivity of 36% and a specificity of 78%, respectively, to detect hyposmia/anosmia in our population.

CONCLUSIONS

Although lung transplantation does not seem to have an impact on olfactory performance, sense of smell is significantly below the average in lung transplant recipients and patients on the waiting list. In both groups, olfactory performance is significantly associated with QoL. Furthermore, self-estimation of olfactory function shows inadequately low sensitivity and specificity.

Complaints of olfactory disorders: epidemiology, assessment and clinical implications

PURPOSE OF REVIEW

Recent studies illuminate the difficulties that patients with olfactory disorder face in daily life, which underlines the need to understand its prevalence, and to diagnose and treat these patients. The purpose of the present review is to characterize olfactory disorders and describe associated complaints, present recent insights into epidemiology, suggest procedures to assess these disorders, and discuss clinical implications.

RECENT FINDINGS

A compilation of previous and new studies of olfactory disorders suggests associated complaints of poor quality of life, depression, and various specific consequences. Epidemiological studies show that loss in odor sensitivity is common in both general and clinical populations, whereas dysosmia is less common in general populations but frequent in clinical populations. The most common etiologies are post-upper respiratory infection, nasal/sinus disease and head trauma.

SUMMARY

Procedures to diagnose olfactory disorders and to identify etiologies are available. Depending on etiology, certain types of treatment are often successful, such as endoscopic sinus surgery and corticosteroid administration in nasal/sinus disease. In post-upper respiratory infection and head trauma, spontaneous recovery is fairly high. In any case, it is advisable to counsel the patient with regards to strategies to cope with olfactory disorders.

Olfactory dysfunction in temporal lobe epilepsy: a case of ictus-related parosmia

Olfactory abnormalities in temporal lobe epilepsy (TLE) usually involve either brief hallucinations prior to seizures or chronic impairments in odor discrimination and identification. We describe the case of a man (B.C.) with TLE with an unusual presentation, an ictus-related parosmia. B.C. reported distorted perception of odor quality and hedonics that could provoke nausea and gagging, typically at its most extreme in the week or so following a seizure. Measures of B.C.'s olfactory functioning were obtained at stages of the ictal cycle when parosmia symptoms were severe and when they had decreased. Unlike other parosmics, B.C.'s detection thresholds were always normal, and unlike others with TLE, he evidenced little impairment in identification or discrimination. Testing during a period of more severe parosmia suggested that B.C.'s experiences might be the result of hedonic changes. We argue this may be the effect of seizure activity on the amygdala, which is known to be involved in mediating emotive reactions to odors.

Retronasal and Orthonasal Olfactory Function in Relation to Olfactory Bulb Volume in Patients With Posttraumatic Loss of Smell

OBJECTIVE

The aims of this study were to evaluate olfactory function with orthonasal and retronasal testing in patients with posttraumatic olfactory loss and to investigate the relation between residual olfactory function and olfactory bulb (OB) volume.

METHOD

A retrospective study of 25 patients with posttraumatic olfactory loss was performed. Orthonasal olfactory function was assessed with the Sniffin' Sticks test kit; retronasal olfactory function was assessed with intraorally applied odors. Magnetic resonance imaging was used to determine OB volume and cortical damage in the frontal and temporal areas.

RESULTS

The main outcomes of the present study were the demonstration of a correlation between olfactory function and OB volume, which was more pronounced for retronasal than for orthonasal olfactory function; retronasal olfactory function was most affected in the patients with the most extensive cerebral damage and was least compromised in patients without such damage; OB volumes were smaller in patients with parosmia compared with those without; and the presence of parosmia was clearly associated with the presence of cerebral damage.

CONCLUSION

The data confirm that OB volume is an indicator of olfactory function but, interestingly, in this study, it is largely determined by retronasal olfactory sensitivity. In addition, these results emphasize the role of higher cortical centers in olfactory function, and especially in parosmia, which may, at least in some cases, be related to lesions in the fronto-orbital and anterior temporal cortices. It would be of interest to investigate OB volume further in relation to the prognosis of the disorder.

Euosmia: a rare form of parosmia

The nature of qualitative olfactory disorders such as phantosmia and parosmia is a matter of debate. Parosmia and phantosmia mainly occur in combination with post-traumatic or post-infectious olfactory loss. Rare causes of these disorders such as brain tumors, side-effects of drugs, paraneoplastic syndromes, psychiatric disorders or intracerebral haemorrhage have been reported. Parosmias are distorted sensations of smell elicited by an odor, whereas phantosmias persist permanently or occur without the presence of an odor source. Phantosmias differ widely in terms of their nature. In contrast, parosmias always seem to be unpleasant. We report the case of a female with post-infectious hyposmia who reported a pleasant parosmia to selected odorants. We have called this rare clinical presentation euosmia.