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PubMed1999

Traumatic brain injury assessed with olfactory event-related brain potentials.

Olfactory event-related potentials (OERPs) were evaluated to develop an objective, quantitative assessment of sensory and cognitive olfactory loss following traumatic brain injury (TBI). Subjects included 25 TBI patients and 25 age/gender-matched healthy controls. Following standard clinical evaluation of smell function, TBI patients were divided into three groups: 12 anosmics (loss of smell), 6 hyposmics (reduced smell), and 7 normosmics (normal smell). Cognitive ability was assessed using the Trail Making Test (A and B). OERPs were recorded monopolarly from midline electrode sites using an amyl acetate stimulus with a 60-second interstimulus interval; subjects estimated the magnitude of each odor stimulus. Anosmic TBI patients were also tested with OERPs using ammonia to ensure trigeminal nerve function. Amyl acetate OERPs demonstrated that the sensory N1 and P2 amplitudes and the cognitive P3 amplitudes were absent in the anosmic TBI patients and greatly reduced in the hyposmic and normosmic TBI patients compared to healthy controls. The trigeminal OERPs from the anosmic TBI patients were within normal limits, indicating that the primary olfactory deficits were objectively measured with OERPs. The relationship between the OERPs and neuropsychologic test performance supports the cognitive loss associated with TBI. The present study lends support to the utility of OERPs as an objective tool for measuring sensory and cognitive loss after traumatic brain injury.

Adult↗
PubMed2004

Olfactory function distinguishes vascular parkinsonism from Parkinson's disease.

OBJECTIVE: To compare olfactory function in vascular parkinsonism and Parkinson's disease diagnosed according to published clinical diagnostic criteria. METHODS: The University of Pennsylvania smell identification test (UPSIT) was carried out in 14 patients with vascular parkinsonism, 18 with Parkinson's disease, and 27 normal controls matched for age, sex, and smoking status. RESULTS: UPSIT scores in vascular parkinsonism (mean 26.1, 95% confidence interval, 23.1 to 29.0) were significantly better than in Parkinson's disease (mean 17.1 (14.5 to 19.7)) (p<0.0001), and did not differ from the healthy controls (mean 27.6 (25.8 to 29.4)) (p = 0.32). CONCLUSIONS: Testing olfactory function may be helpful in differentiating vascular parkinsonism from Parkinson's disease.

Aged↗
PubMed2005

Olfactory involvement in aging and Alzheimer's disease: an autopsy study.

Olfactory dysfunction and tau pathology in the olfactory bulb increase with the severity of Alzheimer's disease. We report data of a postmortem study in the aged. 130 autopsy cases (81 female, 49 male, aged 61-102, mean 82.48 +/- 4.35 SD) years, underwent a standardized neuropathological assessment with immunohistochemical study of tau pathology in the olfactory bulb and nerve and of Alzheimer's disease using established criteria including Braak staging. All cases of definite Alzheimer's disease (Braak stages 5 and 6) (n = 40) showed large numbers of neuropil threads and neurofibrillary tangles, with amyloid deposits in 32.5% and neuritic plaques in one single case in the olfactory system. Braak stage 4 (n = 27) was associated with mild to moderate tau pathology in 85.2%, and amyloid plaques in 1.1%, Braak stage 3 (n = 28) with olfactory tau lesions in 37.0% and amyloid deposits in one single case, Braak stages 3 and 4 with olfactory tau lesions in 61.1%. Braak stage 2 (n = 15) showed olfactory tau pathology in 31.2%, whereas Braak stages 0 and 1 (n = 15) were all negative. The olfactory system tau score showed highly significant correlations with neuritic Braak stages in the brain, while both scores showed significant but low correlations with age. These data confirm previous studies demonstrating abundant tau pathology in the olfactory system in all definite Alzheimer's disease cases, in two-thirds of limbic Alzheimer's disease, and in almost one-third of non-demented elderly persons with Braak stage 2. There are strong correlations between tau pathology in the olfactory and limbic systems, both with similar increase in severity. Clinical dementia correlated with both Braak and olfactory system tau scores. Since the involvement of both systems is associated with a high risk of cognitive decline, future studies should validate the sensitivity of olfactory mucosa biopsies in the diagnosis of Alzheimer's disease.

Aged↗
PubMed2002

Olfactory acuity and cognitive function converge in older adulthood: support for the common cause hypothesis.

Visual and auditory thresholds and cognitive variables have shown converging losses in old age, which might exist because standard cognitive tests rely on these modalities for assessment. The present study investigated the common cause hypothesis in another sensory modality. Structural equation modeling tested the fit of a model representing the common cause hypothesis for olfactory acuity and cognitive function data from 98 nondemented older adults and 103 younger adults. The model fit better the data from the older adults, consistent with the common cause hypothesis. In addition, unique influences of age beyond those shared between cognitive and sensory variables were also demonstrated. The results suggest that olfactory functioning may be a valid indicator of the integrity of the aging brain in older adults.

Adolescent↗
PubMedDate not supplied

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.

Adult↗
PubMed2006

Executive function and memory in relation to olfactory deficits in alcohol-dependent patients.

BACKGROUND: Prior research indicates that chronic alcoholism is accompanied by olfactory deficits. These have been suggested to reflect dysfunctions in olfactory brain regions. The present study investigated the role of neurocognitive functioning in tests (executive function and memory) sensitive to the functional integrity of brain areas that are crucial to olfactory processing in patients with alcohol dependence. METHODS: Performance on olfactory functions (detection threshold, quality discrimination, identification), executive function (Wisconsin Card Sorting Test), and memory (German version of the California Verbal Learning Test) was assessed in 32 alcohol-dependent patients and 30 healthy comparison subjects, comparable in age, gender, and smoking status. RESULTS: Compared with controls, alcohol-dependent patients were impaired in all 3 domains, olfactory functions, executive function, and memory. In patients, olfactory discrimination ability was positively correlated with executive function performance. Regression analyses conducted to clarify the relation between group (patients vs controls), executive function, memory, and olfactory functions indicated that group was the only significant predictor of olfactory detection threshold and identification, and both group and executive function were found to be the significant predictors of olfactory discrimination. CONCLUSIONS: Olfactory deficits in alcohol dependence appear to be associated with prefrontal cognitive dysfunction. Results indicate that olfactory quality discrimination deficits are related to executive function impairment. These findings add to the available research on frontal lobe dysfunction in alcoholism, suggesting that alcohol-related olfactory discrimination deficits may be associated with impairment in the functional integrity of the prefrontal lobe.

Adult↗
PubMed2005

Anosmia is very common in the Lewy body variant of Alzheimer's disease.

BACKGROUND: Olfactory abnormalities are reported in Alzheimer's disease and Parkinson's disease. Anosmia appears to be common in dementia with Lewy bodies but not in pure Alzheimer's disease. OBJECTIVE: To determine whether anosmia improves discrimination between the Lewy body variant (LBV) of Alzheimer's disease and "pure" Alzheimer's disease. METHODS: 106 cases of necropsy confirmed pure Alzheimer's disease (n = 89) or LBV (n = 17) were reviewed. All had received butanol odour threshold testing. Anosmia was defined as a score < or = 1.0 on a 0-9 point scale. Logistic regression analysis was used to model potential predictors (for example, parkinsonism, smoking, hallucinations) of neuropathological diagnosis and anosmia. RESULTS: LBV cases had an increased prevalence of anosmia (65%) compared with Alzheimer's disease (23%; odds ratio (OR) = 6.3, p = 0.00045), or normal elderly people (6.7%). Within the dementia cases, the negative predictive value (92%) and specificity (78%) of anosmia were both good; sensitivity for detecting LBV was 65%, but the positive predictive value (PPV) was only 35%. Logistic regression models showed anosmia (OR = 5.4, p = 0.005) and visual hallucinations (OR = 7.3, p = 0.007) were strong independent predictors of Lewy body pathology. When anosmia was added as a core feature to consensus diagnostic criteria for probable Lewy body dementia, five additional cases of LBV were detected (29% increased sensitivity), but with four additional false positives (1% increased discrimination, 4% decreased specificity, 33% decreased PPV). CONCLUSIONS: Anosmia is very common in LBV. Adding anosmia as a core feature improved sensitivity for detecting LBV, but did not improve discrimination between Alzheimer's disease and LBV owing to a concomitant increase in false positives.

1-Butanol↗
PubMedDate not supplied

Hypogeusia, dysgeusia, hyposmia, and dysosmia following influenza-like infection.

Hypogeusia, with or without dysgenusia, and hyposmia, with or without dysosmia, followed an influenzal-like infection in 87 of 143 consecutive patients who presented at the Taste and Smell Clinic at the NIH with taste and smell abnormalities. Findings in this disease included pale nasal mucous membranes with marked patency of the nasal airway, a postive Rudolph sign, elevated detection and recognition thresholds for several tastants and odorants, disruption of the pore region of the tast dub observed on electron microscopy and infiltration of the upper lamina propria of the nasal mucous membrane wih chronic inflammatory cells observed on light microscopy. These findings, taken together, are relatively specific for the diagnosis of this surprisingly common disorder.

Adult↗
PubMed1991

Otologic sequelae after pneumococcal meningitis: a survey of 164 consecutive cases with a follow-up of 94 survivors.

As part of a comprehensive study on sequelae after pneumococcal meningitis, 94 of 111 consecutive survivors were re-examined 4 to 16 years after discharge. Twenty-three patients had otological sequelae after pneumococcal meningitis. In these patients, 17 had hearing losses, 7 had tinnitus, 9 had vertigo, 13 had vestibular areflexia, 4 had loss of smell, and 3 had loss of taste. Among the patients with hearing loss, 4 were bilaterally deaf, 6 were unilaterally deaf, and 2 had mild and 5 had slight hearing losses. From correlations with extensive data from the medical records, preadmission antibiotic treatment appeared to protect from acousticovestibular damage. Purulent otitis media and otosurgical intervention did not correlate to the fatality rate or the development of sequelae. Acute purulent otitis media appeared as a concomitant manifestation, rather than the focus of pneumococcal meningitis.

Adolescent↗