1,720,971 research outputs found
The impact of regional 99mTc-HMPAO single-photon-emission computed tomography (SPECT) imaging on clinician diagnostic confidence in a mixed cognitive impairment sample
No full textAIM:To assess the clinical impact of regional cerebral blood flow (rCBF) single-photon-emission computed tomography (SPECT) imaging on diagnosis and clinician diagnostic confidence in a cohort of individuals with cognitive impairment. MATERIALS AND METHODS:Forty-one clinicians who referred 79 patients for a [99mTc]-hexamethylpropyleneamine oxime (HMPAO) SPECT for cognitive complaints completed a two-part questionnaire to determine the diagnosis and diagnostic confidence (using a 0-100 visual analogue scale [VAS]) before and after imaging. SPECT images were analysed using statistical parametric mapping and interpreted semi-quantitatively. Clinicians were also asked directly for their opinion on whether the imaging contributed to their diagnostic process. RESULTS:Diagnosis changed after imaging in 44% of cases, and confidence was significantly improved (VAS score change= +26.3±22.2) after imaging in cases where the pre-imaging confidence was low (p<0.001). Clinician confidence was not significantly different (VAS score change=-6.6±25.5) after imaging when pre-imaging confidence was moderate to high. Interestingly, a proportion of clinicians with the highest confidence levels became less certain about their diagnosis following imaging results. When asked directly, 96% of clinicians stated that the imaging contributed to the diagnostic process. CONCLUSIONS:In a mixed clinical cognitive impairment cohort, perfusion SPECT is valued by referring clinicians and contributes to diagnostic decision making. Imaging is of particular value when diagnostic confidence is low prior to imagin
Lobar Atrophy in Frontotemporal Dementia: Diagnostic and Prognostic Implications
No full textWe review the practical importance of lobar atrophy in frontotemporal dementia (FTD), for diagnosis and prognosis. We discuss specific patterns of frontotemporal atrophy that denote clinical and pathological subtypes of FTD (e.g. semantic dementia). We also discuss the unsatisfactory clinical experience of interpreting MRI scans in individual FTD cases, especially the behavioural presentations (without aphasic or motor impairments). This issue is explored by examining the FTD phenocopy concept. Lobar atrophy emerges as a key observation in defining behavioural FTD patients whose symptoms are likely to progress. In a situation where objective clinical data are few, we highlight the importance of applying caution before diagnosing FTD is the absence of visible brain atrophy.</p
Disgust and happiness recognition correlate with anteroventral insula and amygdala volume respectively in preclinical Huntington's disease
No full textPatients with Huntington's disease (HD) can show disproportionate impairments in recognizing facial signals of disgust, but the neural basis of this deficit remains unclear. Functional imaging studies have implicated the anterior insula in the ability to recognize disgust, but have identified other structures as well, including the basal ganglia. In view of variable insula and basal ganglia volume changes in HD, we used voxel-based morphometry to map regional variations in gray matter (GM) volume in participants carrying the mutation for HD, and correlated this with their performance on a test of facial emotion recognition for six basic emotions (disgust, fear, anger, happiness, sadness, surprise). The volume of the anteroventral insula was strongly correlated with performance on the disgust recognition task. The amygdala volume (bilaterally) correlated with the ability to recognize happy facial expressions. There was marked specificity of the regional correlations for the emotion involved. Recognition of other emotion expressions, or more general cognitive or motor performance as measured by a standardized rating scale, did not correlate with regional brain volume in this group. Control participants showed no effect for any measure. The strong linear correlations for disgust and happiness recognition imply direct involvement of the anterior insula in disgust appreciation, and a similar role for the amygdala in recognizing happy facial expressions. The absence of a significant correlation with the basal ganglia suggests a less critical role for these structures in disgust recognition than has previously been suggested. The findings also highlight the role of neurodegenerative diseases combined with statistical imaging techniques in elucidating the brain basis of behavior and cognition
Hybrid simulation modelling for dementia care services planning
No full textDementia is an increasing problem in today’s ageing society, and meeting future demand for care is a major concern for policy-makers and planners. This paper presents a novel hybrid simulation model that simultaneously takes population-level and patient-level perspectives to calculate the numbers of patients at different stages of disease severity over time, and their associated care costs. System Dynamics is used at population level to capture ageing, dementia onset, and all-cause mortality, whereas disease progression is modelled at individual patient level using Agent-Based methods. This enables the model to account for variability between patients in the rate of cognitive decline, dementia-related mortality and response to treatment interventions. Using epidemiological data from the medical literature, disease progression is modelled via a longitudinal clustering method to identify progression type, followed by mixed-effects regression to reflect each individual’s rate of cognitive decline. Results are presented for population data from the south of England, and show that the currently available interventions have only modest effects at population level
Behavioural variant frontotemporal dementia: not all it seems?
No full textBackground: the diagnosis of the behavioural variant of frontotemporal dementia (bvFTD) can be challenging. At present there is a paucity of prospective work addressing the specificity of current diagnostic criteria for bvFTD with respect to long-term outcome (i.e., false positives versus true positives).Methods: here we report two individuals who met current clinical criteria for bvFTD and who underwent detailed long-term clinical and neuropsychological follow-up. In addition, both had serial volumetric MRI and functional metabolic (FDG-PET) imaging separated by 5 years.Results: one case had a slow clinical decline as well as both progressive atrophy and hypometabolism in a frontotemporal distribution, consistent with a neurodegenerative FTD syndrome. However, the second developed neither atrophy nor hypometabolism and remained clinically stable, a decade from symptom onset.Conclusion: we propose that these cases illustrate that while there may be a slow evolution in bvFTD, it is possible that some cases who meet current criteria may not have a neurodegenerative syndrome. If correct, this hypothesis has important implications for the current diagnostic criteria. A potential hierarchy for diagnostic certainty in bvFTD is suggested
Can progressive and non-progressive behavioural variant frontotemporal dementia be distinguished at presentation?
No full textBackground: Recent findings suggest that patients with behavioural variant frontotemporal dementia (bv-FTD) differ in their disease progression (progressive vs nonprogressive patients). The current study investigates whether the two groups can be discriminated by their clinical features at first presentation. Methods: Archival clinical data of the Early Onset Dementia Clinic, Cambridge, UK, were analysed for 71 patients with bv-FTD: 45 progressive and 26 nonprogressive cases with more than 3 years of follow-up. Results: The subgroups were largely indistinguishable on the basis of the presenting clinical features but could be distinguished on general cognitive (Addenbrooke's Cognitive Examination-revised) and selected supportive diagnostic features (distractibility, stereotypic speech, impaired activities of daily living (ADLs) and current depression). Conclusions: Progressive and non-progressive patients are difficult to differentiate on the basis of current clinical diagnostic criteria for FTD but a combination of general cognitive, executive dysfunction and impaired ADL measures appear to be the most promising discriminators
Combined magnetic resonance imaging and positron emission tomography brain imaging in behavioural variant frontotemporal degeneration: Refining the clinical phenotype
No full textIn patients with the behavioural variant of frontotemporal dementia, prognosis is often surprisingly good when there is normal structural imaging at presentation. Imaging abnormalities are not, however, mandatory for diagnosis, which in the absence of suitable biomarkers, remains entirely clinical. We aimed to test whether cases with normal structural imaging have hypometabolism suggestive of underlying neurodegeneration, or whether it is likely that such patients are false positive diagnoses of behavioural variant frontotemporal dementia. Patients with this disease (n 24) and age-matched controls (n 12) underwent both magnetic resonance imaging (MRI) and quantitative fluorodeoxyglucose-positron emission tomography (FDG-PET) scanning, together with clinical and behavioural assessments. Regions of interest were used to calculate metabolic rate in frontotemporal and control regions. Using a semi-quantitative visual rating scale, patients were divided into MRI-abnormal (n 15) and MRI-normal groups (n 9). There was definite frontotemporal hypometabolism in the MRI-abnormal group (particularly in the mesial and orbitofrontal regions) even after accounting for brain volume loss, whereas the MRI-normal group was similar to controls in all regions. In contrast, cognitive and behavioural indices did not separate the two behavioural variant frontotemporal dementia patient groups. The results suggest that the clinical syndrome of the behavioural variant of frontotemporal dementia may not be specific for a neurodegenerative disease, and we hypothesize the existence of a phenocopy. A number of alternative neuropsychiatric and developmental explanations are discussed. We advise caution in diagnosing the illness in patients without imaging abnormalities, and propose that imaging findings are included in criteria for diagnosis
Sensitivity of current criteria for the diagnosis of behavioral variant frontotemporal dementia
No full textBACKGROUND:: Diagnosis of behavioral variant frontotemporal dementia (bvFTD) relies on criteria that are constraining and potentially ambiguous. Some features are open to clinical interpretation and their prevalence unknown. This study investigated the sensitivity of current diagnostic criteria in a large group of patients with bvFTD. METHODS:: Forty-five patients with clear evidence of bvFTD as judged by progressive clinical decline (>3 years) with marked frontal features and significant frontal brain atrophy on brain MRI were included. Thirty-two have died; pathologic confirmation of frontotemporal lobar degeneration was found in all 18 coming to autopsy. We established the prevalence of core and supportive diagnostic features at presentation and with disease progression. RESULTS:: Only 25/45 patients (56%) showed all five core features necessary for a diagnosis of bvFTD at initial presentation and 33/45 (73%) as their disease progressed. Two core features, emotional blunting and loss of insight, were never observed in 25% and 13% of cases. Executive dysfunction, hyperorality, mental inflexibility, and distractibility were the only supportive features present in >50% of cases at initial presentation. Although not a diagnostic feature, impaired activities of daily living was present in 33/45 patients (73%). CONCLUSIONS:: Strict application of the criteria misses a significant proportion of patients. Many supportive features have low prevalence and are clinically not useful. Revision of the criteria to include level of certainty (definite, probable, possible) dependent on the number of features present and the presence of ancillary information (e.g., brain atrophy, neuropsychological abnormalities, impaired activities of daily living) is encouraged
Progression of structural neuropathology in preclinical Huntington's disease: a tensor based morphometry study
No full textBackground and objectives: regional cerebral atrophy occurs in carriers of the Huntington’s disease (HD) gene mutation before clinical diagnosis is possible. The current inability to reliably measure progression of pathology in this preclinical phase impedes development of therapies to delay clinical onset. We hypothesised that longitudinal statistical imaging would detect progression of structural pathology in preclinical carriers of the HD gene mutation, in the absence of measurable clinical change.Methods: thirty subjects (17 preclinical mutation positive, 13 mutation negative) underwent serial clinical and magnetic resonance imaging (MRI) assessments over an interval of 2 years. Statistically significant changes in regional grey and white matter volume on MRI were analysed using tensor based morphometry (TBM). This technique derives a voxel-wise estimation of regional tissue volume change from the deformation field required to warp a subject’s early to late T1 images.Results: over 2 years, there was progressive regional grey matter atrophy in mutation-positive relative to negative subjects, without significant clinical progression of disease. Significant grey matter volume loss was limited to bilateral putamen and globus pallidus externa (GPe), left caudate nucleus, and left ventral midbrain in the region of the substantia nigra.Conclusions: while these results are consistent with previous cross sectional pathologic and morphometric studies, significant progression of atrophy in HD before the onset of significant clinical decline is now demonstrable with longitudinal statistical imaging. Such measures could be used to assess the efficacy of potential disease modifying drugs in slowing the progression of pathology before confirmed clinical onset of HD
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