Olfactory and Gustatory Dysfunction in Patients With Autoimmune Encephalitis

Geran, Rohat; Uecker, Florian C.; Prüß, Harald; Hæusler, Karl Georg; Paul, Friedemann; Ruprecht, Klemens; Harms, Lutz; Schmidt, Felix

doi:10.3389/fneur.2019.00480

Cited by 9 publications

(8 citation statements)

References 51 publications

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“…Fewer studies have also described olfactory alterations related to neuroimmunological disorders, such as systemic lupus erythematosus, multiple sclerosis and neuromyelitis optica [ 4 ]. Finally, smell impairment has been documented through a psychophysical test in a single cohort of subjects diagnosed with autoimmune encephalitis (AE) [ 5 ], and hyposmia has been recently reported as a possible manifestation of the newly recognized anti-adenylate kinase 5 (AK5) encephalitis [ 6 ]. Following these findings, we assessed the olfactory function of 19 AE patients, comparing them with a group of sex- and age-matched healthy controls (HC), to confirm olfactory deficits in this patient population and investigate possible correlations between olfaction and electro-clinical and neuroimaging findings.…”

Section: Introductionmentioning

confidence: 99%

Olfactory impairment in autoimmune encephalitis: another piece of the puzzle

et al. 2022

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Background Despite being long neglected, olfaction has recently become a focus of intense research in neuroscience, as smell impairment has been consistently documented in both neurodegenerative and neuroinflammatory diseases. Considering the close anatomo-functional correlations between the limbic system and the central olfactory structures, we investigated olfaction in a population of patients with autoimmune encephalitis (AE). Methods Nineteen adult subjects (14 males, median age 64 years) diagnosed with definite (14/19) or possible (5/19) AE and followed for ≥ 6 months were enrolled. The Brief Smell Identification Test (B-SIT), a 12-item, forced-choice, scratch-and-sniff measure, was used to assess the patients’ olfactory function in comparison with a group of sex- and age-matched healthy controls (HC). According to the B-SIT score, subjects were classified as anosmic (< 6), hyposmic (6–8) and normal (≥ 9). Electro-clinical, laboratory and neuroimaging findings were reviewed. Results Smell impairment was revealed in 15/19 patients (9 hyposmic, 6 anosmic), compared with 5/19 HC ( p = 0.0029). Age, gender and smoking habits did not affect the participants’ performance at B-SIT. Olfactory dysfunction appeared more common among patients with definite AE ( p = 0.0374), regardless of autoantibody status. Subjects with higher modified Rankin Scale (mRS) scores at AE onset more likely presented hyposmia/anosmia ( p = 0.033), and so did those with bilateral ictal/interictal EEG abnormalities ( p = 0.006). Conclusions We found olfaction to be impaired in a significantly large proportion of AE cases. Smell deficits appeared more common in subjects with severe AE (as indicated by both definite diagnosis and higher mRS score), and might represent an additional feature of immune-mediated encephalitis. Supplementary Information The online version contains supplementary material available at 10.1007/s00415-022-10959-6.

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Section: Introductionmentioning

confidence: 99%

Olfactory impairment in autoimmune encephalitis: another piece of the puzzle

et al. 2022

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“…OD in all 3 domains (threshold, discrimination, and identification) was found to be highly prevalent in patients with autoimmune encephalitis, while rhinitis is a known side effect of mycophenolate mofetil and may have contributed to the smell loss in this case. 26 After excluding these 2 cases, the cut-off score in SS12 that indicates neurodegeneration rather than PPD remained ≤ 8 with higher specificity (77.4%) than the original analysis. The third patient who was normosmic was initially diagnosed as having DLB.…”

Section: Discussionmentioning

confidence: 81%

Odor Identification Testing Can Assist in the Clinical Distinction Between Psychiatric Disorders and Neurological/Neurodegenerative Disorders

Pachi

Evans²,

Loi³

et al. 2021

Alzheimer Disease &Amp; Associated Disorders

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Background/Objectives: The aim was to identify whether performance on olfactory identification can distinguish neurological/neurodegenerative disorders (NNDs) from primary psychiatric disorders (PPDs). Methods: This is a cross-sectional retrospective study of inpatients assessed in Neuropsychiatry, Royal Melbourne Hospital. Data extracted from the admission records included: demographics, tobacco use, medical comorbidities, cognitive function using the Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG), and odor identification using the Sniffin’ Sticks Screening 12 test. The final diagnosis for patients was informed by established diagnostic criteria. Results: A total 121 patients were included. Eighty-eight patients (73%) were diagnosed with neurological or neurodegenerative disease, including Alzheimers dementia, frontotemporal dementia, Lewy body parkinsonian-related dementias (Parkinson disease, multiple system atrophy, dementia with Lewy bodies) and other neurological causes of dementia; 33 patients (27%) were diagnosed with PPDs (including mood and psychotic disorders). Patients who scored ≤8 on the Sniffin’ Sticks Screening 12 test were more likely to have NND than PPD, even after adjustment for age, sex and tobacco use (P=0.009, adjusted odds ratios=3.85, 95% confidence interval=1.40-10.62). Receiver operating characteristic curve analyses demonstrated that a score of ≤8 differentiated NND from PPD with sensitivity of 57% and specificity of 73% (receiver operating characteristic area under the curve of 0.67, P=0.004). Conclusions: Patients with neuropsychiatric difficulties who score 8 or less on Sniffin’ Sticks are more likely to have a neurodegenerative illness. A cut-off score of 8 is potentially a “red flag” for clinicians faced with the diagnostic question of PPD versus NND.

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“…The relatively low TDI scores observed in our neurologic control patients highlight the fact that, albeit quite prevalent, especially in neurodegenerative disorders (23,24), olfactory symptoms in neurologic patients may generally deserve more attention than has hitherto been accorded to them. Interestingly, emerging evidence seems to indicate that, besides classical neurodegenerative disorders, other neurologic disorders such as multiple sclerosis and autoimmune encephalitis may also lead to hyposmia (25,26). Also, the validity of the Sniffin’ Sticks procedure needs further investigation in groups other than healthy controls.…”

Section: Discussionmentioning

confidence: 99%

Lumbar puncture rapidly improves olfaction in patients with idiopathic intracranial hypertension: A cohort study

et al. 2020

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Background A lumbar puncture constitutes an important diagnostic procedure in the evaluation of idiopathic intracranial hypertension. Chronic overflow of cerebrospinal fluid into the sheaths of the olfactory nerves appears to be related to olfactory impairment in these patients. Here, we asked whether cerebrospinal fluid drainage in idiopathic intracranial hypertension patients improves olfactory function. Methods Fourteen idiopathic intracranial hypertension patients and 14 neurologic control patients were investigated before and after lumbar puncture using the extended Sniffin’ Sticks procedure. We assessed odor threshold, discrimination, and identification. In idiopathic intracranial hypertension patients, cerebrospinal fluid was drained until cerebrospinal fluid pressure had normalized. In addition, a third group of 14 healthy controls participated in the two smell tests at similar intervals. Results Relative to healthy controls, threshold, discrimination, and identification composite scores before lumbar puncture were significantly lower in idiopathic intracranial hypertension patients and also in neurologic controls. Following lumbar puncture, threshold, discrimination, and identification scores for neurologic controls remained unchanged whereas idiopathic intracranial hypertension patients showed robust improvement on the composite score as well as on all three subscores (all changes: p < 0.003), quickly regaining olfactory function in the normal range. Cerebrospinal fluid opening pressure was significantly correlated with improvement in threshold, discrimination, and identification score upon cerebrospinal fluid drainage ( r = 0.609, p = 0.021). Conclusion Olfactory impairment is an important, yet underappreciated, clinical feature of idiopathic intracranial hypertension. Lowering of increased intracranial pressure improves hyposmia. Our findings shed new light on the pathophysiology of cerebrospinal fluid circulation in idiopathic intracranial hypertension.

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Olfactory and Gustatory Dysfunction in Patients With Autoimmune Encephalitis

Cited by 9 publications

References 51 publications

Olfactory impairment in autoimmune encephalitis: another piece of the puzzle

Olfactory impairment in autoimmune encephalitis: another piece of the puzzle

Odor Identification Testing Can Assist in the Clinical Distinction Between Psychiatric Disorders and Neurological/Neurodegenerative Disorders

Lumbar puncture rapidly improves olfaction in patients with idiopathic intracranial hypertension: A cohort study

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