-
Handbook of Clinical Neurology 2021The term visual agnosia is used to refer to recognition disorders that are confined to the visual modality, that are not due to an impairment in sensory functions, and...
The term visual agnosia is used to refer to recognition disorders that are confined to the visual modality, that are not due to an impairment in sensory functions, and that cannot be explained by other cognitive deficits or by general reduction in intellectual ability. Here, we describe the different types of visual agnosia that have been reported (form agnosia, integrative agnosia, associative agnosia, transformational and orientation agnosia as well as category-specific impairments such as pure alexia and prosopagnosia) and how they relate to the current understanding of visual object recognition. Together with related disorders such as simultanagnosia, texture agnosia, aphantasia, and optic aphasia, these visual perceptual impairments can have severe consequences for those affected. We suggest how in-depth assessment can be carried out to determine the type and the extent of these impairments. In the context of clinical assessment, a step-by-step approach reflecting a posterior to anterior gradient in visual object recognition, from more perceptual to more memory-related processes, is suggested. Individually tailored interventions targeting the identified impairments can be initiated based on the results of the assessment.
Topics: Agnosia; Cognition Disorders; Humans; Neuropsychological Tests; Orientation; Visual Perception
PubMed: 33832675
DOI: 10.1016/B978-0-12-821377-3.00008-8 -
NeuroImage Jul 2021Lesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also with impairments in the...
Lesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also with impairments in the processing of objects presented under demanding viewing conditions. Evidence from neuroimaging studies and lesion patterns observed in patients with simultanagnosia and agnosia for object orientation suggest similar brain regions to be involved in perception of global shapes and processing of objects in atypical ('non-canonical') orientation. In a localizer experiment, we identified individual temporo-parietal brain areas involved in global shape perception and found significantly higher BOLD signals during the processing of non-canonical compared to canonical objects. In a multivariate approach, we demonstrated that posterior temporo-parietal brain areas show distinct voxel patterns for non-canonical and canonical objects and that voxel patterns of global shapes are more similar to those of objects in non-canonical compared to canonical viewing conditions. These results suggest that temporo-parietal brain areas are not only involved in global shape perception but might serve a more general mechanism of complex object perception. Our results challenge a strict attribution of object processing to the ventral visual stream by suggesting specific dorsal contributions in more demanding viewing conditions.
Topics: Adult; Female; Humans; Magnetic Resonance Imaging; Male; Parietal Lobe; Photic Stimulation; Recognition, Psychology; Temporal Lobe; Visual Perception; Young Adult
PubMed: 33757908
DOI: 10.1016/j.neuroimage.2021.117982 -
BMC Neurology Jan 2021Glucocerebrosidase (GBA) heterozygous variants are the most important genetic risk factor for the development of alpha-synucleinopathies (i.e., Parkinson's disease and...
BACKGROUND
Glucocerebrosidase (GBA) heterozygous variants are the most important genetic risk factor for the development of alpha-synucleinopathies (i.e., Parkinson's disease and Dementia with Lewy Bodies). Herein, we report for the first time on a patient with a clinical diagnosis of Posterior Cortical Atrophy, carrier of the common GBA heterozygous variant N370S (c.1226A > G).
CASE PRESENTATION
A 44-year-old woman with positive familial history for Dementia with Lewy Bodies disclosed three related signs characterizing the Balint's syndrome: ocular apraxia, optic ataxia and simultanagnosia. Over 2-year follow up, overt gaze apraxia (psychic paralysis of gaze) appeared leading to functional blindness. Given her young age at onset and positive familial history, she underwent a next-generation-sequencing (NGS) based screening of a panel of 32 genes related to neurodegenerative conditions within the ANAMNESYS (An origiNal Approach to study faMiliarity in NEurodegenerative SYndromeS) study. NGS demonstrated the N370S variant in the GBA gene (rs76763715), confirmed by Sanger sequencing. This is a relatively common variant, with predicted mild impact, already reported to occur in 2.4% of PD Italian patients; however, neither this nor other GBA variants have ever been reported to date in patients with Posterior Cortical Atrophy. Glucocerebrosidase activity was investigated and found to be significantly reduced (4.72 nmol/h/mg) compared to healthy controls as well as patients affected by neurodegenerative diseases, further supporting pathogenicity of the GBA variant.
CONCLUSIONS
We report on a patient with a clinical diagnosis of Posterior Cortical Atrophy, carrier of the GBA heterozygous variant N370S (c.1226A > G; p.Asn409Ser) determining reduced GCase activity. This report also confirms the role of NGS-based targeted gene analysis in detecting peculiar clinical phenotypes associated with known pathogenic mutations and reinforces the knowledge that carriers of genetic variants often present phenotypic overlaps across different neurodegenerative syndromes, highlighting the limitations of current clinical diagnostic criteria in defining boundaries between distinct conditions and the difficulties of clinicians in reaching the best clinical diagnosis.
Topics: Adult; Age of Onset; Atrophy; Female; Glucosylceramidase; Heterozygote; Humans; Italy; Mutation; Neurodegenerative Diseases; Phenotype
PubMed: 33435912
DOI: 10.1186/s12883-020-02023-5 -
Neurological Sciences : Official... May 2021Selective bilateral lesions of the parietal-occipital lobes can lead to an uncommon and incompletely understood clinical entity, Balint' syndrome, which consists of...
BACKGROUND
Selective bilateral lesions of the parietal-occipital lobes can lead to an uncommon and incompletely understood clinical entity, Balint' syndrome, which consists of simultanagnosia, oculomotor apraxia, optic ataxia and difficulty in perceiving distances between objects.
CASE PRESENTATION
We herein report a rare presentation of Balint's syndrome in a 65-year-old woman suffering from stroke and SARS-CoV2 infection.
CONCLUSION
During SARS-CoV2 pandemic, Italian physicians were forced to work with less instrumental diagnostic resources, relying on their clinical knowledge mostly. The aim of this case report is to highlight the importance of performing a precise neurological evaluation, particularly during these challenging times: it might avoid incorrect diagnosis and favour the discovery of rare clinical diseases.
Topics: Aged; Apraxias; COVID-19; Female; Humans; Physicians; RNA, Viral; SARS-CoV-2
PubMed: 33400067
DOI: 10.1007/s10072-020-04934-0 -
Neurocase Dec 2020We report a patient with asymmetric Bálint's syndrome (predominantly right-sided oculomotor apraxia and simultanagnosia and optic ataxia for the right hemispace), and...
Asymmetric Bálint's syndrome with multimodal agnosia, bilateral agraphesthesia, and ineffective kinesthetic reading due to subcortical hemorrhage in the left parieto-occipito-temporal area.
We report a patient with asymmetric Bálint's syndrome (predominantly right-sided oculomotor apraxia and simultanagnosia and optic ataxia for the right hemispace), and multimodal agnosia (apperceptive visual agnosia and bilateral associative tactile agnosia) with accompanying right hemianopia, bilateral agraphesthesia, hemispatial neglect, global alexia with unavailable kinesthetic reading, and lexical agraphia for kanji (Japanese morphograms), after hemorrhage in the left parieto-occipito-temporal area. The coexistence of tactile agnosia, bilateral agraphesthesia, and ineffective kinesthetic reading suggests that tactile-kinesthetic information can be interrupted because of damage to the fiber connection from the parietal lobe to the occipito-temporal area, leading to these tactually related cognitive impairments.
Topics: Aged; Agnosia; Agraphia; Apraxias; Ataxia; Cerebral Hemorrhage; Cogan Syndrome; Dyslexia; Humans; Language Disorders; Magnetic Resonance Imaging; Male; Occipital Lobe; Parietal Lobe; Perceptual Disorders; Syndrome; Temporal Lobe; Touch Perception; Visual Perception
PubMed: 33103577
DOI: 10.1080/13554794.2020.1831546 -
Clinical Nuclear Medicine Feb 2021Balint syndrome is a rare neurological disorder characterized by simultanagnosia, optic ataxia, and ocular apraxia, and its etiology can be very heterogeneous. Diagnosis...
Balint syndrome is a rare neurological disorder characterized by simultanagnosia, optic ataxia, and ocular apraxia, and its etiology can be very heterogeneous. Diagnosis is based on neuropsychological evaluation, but brain radiological and nuclear medicine imaging also plays an important role. Because few case reports have been published in literature, in this work, we present 2 patients affected by Balint syndrome in which 18F-FDG PET/CT helped in the diagnosis and follow-up.
Topics: Female; Fluorodeoxyglucose F18; Follow-Up Studies; Humans; Male; Middle Aged; Nervous System Diseases; Positron Emission Tomography Computed Tomography
PubMed: 33065619
DOI: 10.1097/RLU.0000000000003335 -
European Journal of Neurology Jan 2021Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome, defined by a distinctive clinical-radiological profile, with Alzheimer's disease (AD) pathology...
BACKGROUND AND PURPOSE
Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome, defined by a distinctive clinical-radiological profile, with Alzheimer's disease (AD) pathology accounting for the majority of cases. The aim of this report was to present the case of a patient with impairment of visual and constructional abilities as initial manifestations.
METHOD
The patient underwent a multidimensional assessment, including neuropsychological evaluation, structural and functional imaging and genetic screening.
RESULTS
Neurological and neuropsychological assessment showed an impairment of constructive and visuo-spatial skills, associated with dyscalculia, simultanagnosia, optic ataxia and oculomotor apraxia. In accordance with the latest consensus criteria, a diagnosis of PCA was made. Consistent with the clinical findings, structural and functional imaging showed a peculiar pattern of atrophy with primary involvement of right parieto-occipital cortices, whereas cerebrospinal fluid biochemical analysis did not reveal a profile compatible with AD pathology. Genetic screening identified a known pathogenic GRN mutation.
CONCLUSION
We present a case of PCA in a GRN mutation carrier in whom a concomitant AD pathological process was excluded. Consequently, although lacking histological data, our case suggests GRN-related pathology causative of PCA. Through this report we provide further evidence for a new neurodegenerative pathway leading to PCA, extending the clinical spectrum of GRN-associated phenotypes.
Topics: Alzheimer Disease; Atrophy; Cerebral Cortex; Humans; Mutation; Occipital Lobe; Progranulins
PubMed: 33030763
DOI: 10.1111/ene.14574 -
Cerebral Cortex (New York, N.Y. : 1991) Jan 2021Simultanagnosia is an impairment in processing multiple visual elements simultaneously consecutive to bilateral posterior parietal damage, and neuroimaging data have...
Simultanagnosia is an impairment in processing multiple visual elements simultaneously consecutive to bilateral posterior parietal damage, and neuroimaging data have specifically implicated the superior parietal lobule (SPL) in multiple element processing. We previously reported that a patient with focal and bilateral lesions of the SPL performed slower than controls in visual search but only for stimuli consisting of separable lines. Here, we further explored this patient's visual processing of plain object (colored disk) versus object consisting of separable lines (letter), presented in isolation (single object) versus in triplets. Identification of objects was normal in isolation but dropped to chance level when surrounded by distracters, irrespective of eccentricity and spacing. We speculate that this poor performance reflects a deficit in processing objects' relative locations within the triplet (for colored disks), aggravated by a deficit in processing the relative location of each separable line (for letters). Confirming this, performance improved when the patient just had to detect the presence of a specific colored disk within the triplets (visual search instruction), while the inability to identify the middle letter was alleviated when the distracters were identical letters that could be grouped, thereby reducing the number of ways individual lines could be bound.
Topics: Adult; Agnosia; Attention; Cognition; Female; Humans; Neuroimaging; Parietal Lobe; Visual Perception
PubMed: 32959044
DOI: 10.1093/cercor/bhaa250 -
Neuropsychology Sep 2020Simultanagnosia, a deficit in holistic visual perception, is among the most prominent features of posterior cortical atrophy (PCA). Deficits in visuoperceptual and...
Simultanagnosia, a deficit in holistic visual perception, is among the most prominent features of posterior cortical atrophy (PCA). Deficits in visuoperceptual and attentional mechanisms could contribute to simultanagnosia. In the present study, we explored the impaired visual perception of global configuration with two main hypotheses: (a) It is due to a deficit in processing low-spatial frequency stimuli, and (b) it arises from deficits in adjusting attentional focus. The visuoperceptual mechanism was explored by asking participants (5 PCA patients and 20 age- and education-matched healthy controls) to report the local and global elements of incongruent hierarchical letters. Stimuli were unbiased (black letters/white background) and parvocellular biased (red letters/green background). A cued T-detection task, where the stimulus onset asynchrony and the cues' features varied, was used to explore focal attention. PCA patients systematically failed in reporting the global but not the local element. The parvocellular-biased condition partially improved the performance in only 1 patient. In the T-detection task, controls responded faster to targets cued by red dots and small cues as compared to no cues. Conversely, the cue's features did not affect patients' performance. Results only partially support the hypothesis according to which simultanagnosia is driven by an impairment in processing low-spatial frequencies. Data indicate a deficit in the flexibility of focal attention that prevents PCA patients from adapting the attentional window to the stimulus features. Simultanagnosia in PCA can be conceptualized as a complex result of a deficit involving visuoperceptual and exogenous attentional mechanisms. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
PubMed: 32940497
DOI: 10.1037/neu0000697 -
Neurology Mar 2021We present the case of a 68-year-old woman who developed progressive visuospatial deficits in a period of 18 months, leading to the loss of her independence for...
We present the case of a 68-year-old woman who developed progressive visuospatial deficits in a period of 18 months, leading to the loss of her independence for activities of daily living. After examination, she showed signs of Balint syndrome with optic ataxia, oculomotor apraxia, and simultanagnosia without visual acuity impairment. After brain imaging showing severe bilateral parieto-occipital association cortex atrophy, a diagnosis of posterior cortical atrophy was made according to the 2017 International Consortium's criteria.
Topics: Aged; Apraxias; Ataxia; Atrophy; Brain; Cerebral Cortex; Cogan Syndrome; Female; Humans; Occipital Lobe; Parietal Lobe; Vision Disorders
PubMed: 32928969
DOI: 10.1212/WNL.0000000000010849