Hiding in plain sight: a closer look at posterior cortical atrophy

Beh, Shin C.; Muthusamy, Brinda; Calabresi, Peter A.; Hart, John; Zee, David S.; Patel, Vivek A.; Frohman, Elliot M.

doi:10.1136/practneurol-2014-000883

Cited by 35 publications

(14 citation statements)

References 42 publications

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“…This disease is often accompanied by visuospatial and visuoperceptual impairments, alexia, features of Bálint’s syndrome, Gerstmann’s syndrome and transcortical sensory aphasia, whereas episodic memory is relatively preserved or only mildly impaired [2]. These clinical features differ from those of typical dementia of the Alzheimer’s type (DAT) as they show preservation of memory, insight, and judgment until late in the clinical course, when the clinical features of PCA and DAT overlap [3]. The most frequent pathological findings in PCA are tau neurofibrillary tangles and beta-amyloid neuritic plaques which are characteristic of Alzheimer’s disease [4], although other pathologies have been described in PCA including corticobasal degeneration, diffuse Lewy body disease, and Creutzfeldt-Jakob disease [5–7]; frontotemporal dementia with progranulin mutation has also been reported [8].…”

Section: Introductionmentioning

confidence: 99%

Clinical, FDG and amyloid PET imaging in posterior cortical atrophy

et al. 2015

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The purpose of this study was to identify the clinical, [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) and amyloid-PET findings in a large cohort of posterior cortical atrophy (PCA) patients, to examine the neural correlates of the classic features of PCA, and to better understand the features associated with early PCA. We prospectively recruited 25 patients who presented to the Mayo Clinic between March 2013 and August 2014 and met diagnostic criteria for PCA. All patients underwent a standardized set of tests and amyloid imaging with [11C] Pittsburg compound B (PiB). Seventeen (68 %) underwent FDG-PET scanning. We divided the cohort at the median disease duration of 4 years in order to assess clinical and FDG-PET correlates of early PCA (n = 13). The most common clinical features were simultanagnosia (92 %), dysgraphia (68 %), poly-mini-myoclonus (64 %) and oculomotor apraxia (56.5 %). On FDG-PET, hypometabolism was observed bilaterally in the lateral and medial parietal and occipital lobes. Simultanagnosia was associated with hypometabolism in the right occipital lobe and posterior cingulum, optic ataxia with hypometabolism in left occipital lobe, and oculomotor apraxia with hypometabolism in the left parietal lobe and posterior cingulate gyrus. All 25 PCA patients were amyloid positive. Simultanagnosia was the only feature present in 85 % of early PCA patients. The syndrome of PCA is associated with posterior hemisphere hypometabolism and with amyloid deposition. Many of the classic features of PCA show associated focal, but not widespread, areas of involvement of these posterior hemispheric regions. Simultanagnosia appears to be the most common and hence sensitive feature of early PCA.

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Section: Introductionmentioning

confidence: 99%

Clinical, FDG and amyloid PET imaging in posterior cortical atrophy

et al. 2015

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“…Posterior cortical atrophy (PCA) is a neurodegenerative condition presenting with progressive visuoperceptual deficits. 5 PCA typically involves dorsal (occipito-parietal) or ventral (occipito-temporal) networks. Even though Alzheimer disease (AD) pathology accounts for a vast majority of PCA cases, 6 patients with this condition show brain degeneration in occipital and temporal areas that extend beyond the atrophy typically seen in patients in the earlier stages of AD.…”

Section: Processing and Recognition Of Anmentioning

confidence: 99%

Neuroanatomical foundations of naming impairments across different neurologic conditions

2015

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The ability to name objects or abstract entities is an essential feature of speech and language, being commonly considered a central component of normal neurologic function. For this reason, the bedside testing of naming performance is part of the neurologic examination, especially since naming impairments can signify the early onset of a progressive disease or the occurrence of a more established problem. Modern neuroscience research suggests that naming relies on specific and distributed networks that operate in concert to support various processing stages, spanning from object recognition to spoken words. Likewise, studies evaluating the types of naming impairments in patients with neurologic conditions have contributed to the understanding of acquired forms of naming impairments and the underlying stages during normal language processing. In this article, we review the neurobiological mechanisms supporting naming, with a focus on the clinical application of these concepts. We provide an overview of the stages of cognitive processing that are hypothesized to support naming. For each stage, we explore the evidence revealing its neural basis, drawing parallels to clinical syndromes that commonly disrupt each stage. We review the patterns of naming impairment across various neurologic conditions, including classic language disorders, such as poststroke aphasia or primary progressive aphasia, as well as other diseases where language impairments may be subtle but helpful for the appropriate diagnosis. In this context, we provide a structured and practical guide for the bedside naming assessments rooted in modern neuroscience, aimed at supporting the evaluation and diagnosis of neurologic conditions that affect language. Neurology ® 2015;85:284-292 GLOSSARY AD 5 Alzheimer disease; AoS 5 apraxia of speech; FTLD 5 frontotemporal lobar degeneration; PCA 5 posterior cortical atrophy; PPA-L 5 logopenic variant of primary progressive aphasia; PPA-S 5 semantic variant of primary progressive aphasia; TLE 5 temporal lobe epilepsy; TOT 5 tip of the tongue.The ability to name objects or abstract entities is essential in everyday speech production. Retrieving the correct word that denotes a specific something relies on an orchestrated sequence of brain processes, ranging from perception of a stimulus to the physical articulation of the sounds used to speak its name. While intimately related, each stage of this complex process relies on the activation of distinct neural circuits. Accordingly, naming impairments may emerge following disruption of one or more of the stages thought to support naming.The process of naming most commonly occurs during discourse, when we are constantly required to retrieve abstract concepts to either understand or deliver a message, or by our need to identify an object perceived in the environment. Thus, naming can relate to an object that was seen, smelled, touched, heard, tasted, or any combination of these modalities. Stimulus processing results in the recognition of the stimulus as a famil...

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“…These clinical syndromes, however, account for only a very small portion of patients with dementia. In addition, recent research suggests that there can be substantial variability regarding the biological substrates associated with some of these syndromes 47, 48 . By contrast, at the current time well-tested diagnostic criteria for mixed AD/VaD dementia are lacking 49 .…”

Section: Discussionmentioning

confidence: 99%

Dissociating Statistically-Determined Alzheimer’s Disease/Vascular Dementia Neuropsychological Syndromes Using White and Gray Neuroradiological Parameters

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Schmalfuss

et al. 2015

JAD

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Objectives To use statistical modeling of neuropsychological data to determine subgroups of dementia patients clinically diagnosed with Alzheimer’s disease (AD) or vascular dementia (VaD) and then, using brain imaging, investigate between group differences in gray and white matter regions of interest. Methods An analysis of neuropsychological functioning was obtained from dementia patients clinically diagnosed with AD/VaD characterized with significant leukoaraiosis (LA) and/or lacunes where a k-means cluster analysis requested a 3-group solution. MRI measures of hippocampal, caudate, ventricular, subcortical lacunar infarction, whole brain volume and LA were analyzed. Three regions of LA volumes were quantified and these included the periventricular (5mm around the ventricles), infracortical (5mm beneath the gray matter), and deep (between periventricular and infracortical) regions. Results Cluster analysis sorted AD/VaD patients into single domain amnestic (n=41), single-domain dysexecutive (n=26), and multi-domain (n=26) phenotypes. The multi-domain patients exhibited worst performance on language tests; however, multi-domain patients were equally impaired on memory tests when compared to amnestic patients. Statistically-determined groups were relatively dissociated using neuroradiological parameters such that amnestic and multi-domain groups presented with smaller hippocampal volume while the dysexecutive group presented with greater deep, periventricular, and whole brain LA. Neither caudate nor lacunar infarction volume differed between cluster-determined groups. Caudate nucleus volume negatively correlated with total LA in the dysexecutive and multi-domain groups. Conclusions Results suggest that embedded within patients diagnosed clinically with AD/VaD spectrum dementia there are at least three distinct subtypes which can be operationally-defined. Further research is needed to assess the neuroradiological substrates underlying statistically-determined AD/VaD spectrum dementia and how statistical modeling can be integrated into existing diagnostic criteria.

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Hiding in plain sight: a closer look at posterior cortical atrophy

Cited by 35 publications

References 42 publications

Clinical, FDG and amyloid PET imaging in posterior cortical atrophy

Clinical, FDG and amyloid PET imaging in posterior cortical atrophy

Neuroanatomical foundations of naming impairments across different neurologic conditions

Dissociating Statistically-Determined Alzheimer’s Disease/Vascular Dementia Neuropsychological Syndromes Using White and Gray Neuroradiological Parameters

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