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Behavioural Neurology 2014We describe a case of dementia with Lewy bodies (DLB) that presented long-lasting preclinical complex polymodal hallucinations.
OBJECTIVE
We describe a case of dementia with Lewy bodies (DLB) that presented long-lasting preclinical complex polymodal hallucinations.
BACKGROUND
Few studies have deeply investigated the characteristics of hallucinations in DLB, especially in the preclinical phase. Moreover, the clinical phenotype of mild cognitive impairment-(MCI-) DLB is poorly understood.
METHODS
The patient was followed for 4 years and a selective phenomenological and cognitive study was performed at the predementia stage.
RESULTS
The phenomenological study showed the presence of hypnagogic and hypnopompic hallucinations that allowed us to make a differential diagnosis between DLB and Charles Bonnet syndrome (CBS). The neuropsychological evaluation showed a multiple domain without amnesia MCI subtype with prefrontal dysexecutive, visuoperceptual, and visuospatial impairments and simultanagnosia, which has not previously been reported in MCI-DLB.
CONCLUSIONS
This study extends the prognostic value of hallucinations for DLB to the preclinical phases. It supports and refines the MCI-DLB concept and identifies simultanagnosia as a possible early cognitive marker. Finally, it confirms an association between hallucinations and visuoperceptual impairments at an intermediate stage of the disease course and strongly supports the hypothesis that hallucinations in the earliest stages of DLB may reflect a narcolepsy-like REM-sleep disorder.
Topics: Aged, 80 and over; Disease Progression; Female; Hallucinations; Humans; Lewy Body Disease; Neuropsychological Tests; Prodromal Symptoms
PubMed: 24868122
DOI: 10.1155/2014/694296 -
Neurology May 2014A 54-year-old woman developed acute hypertensive encephalopathy associated with acetaminophen-induced liver failure. Examination showed blindness with absence of...
A 54-year-old woman developed acute hypertensive encephalopathy associated with acetaminophen-induced liver failure. Examination showed blindness with absence of horizontal and vertical volitional and reflex saccades (video on the ® Web site at Neurology.org, first segment). MRI showed biparieto-occipital signal abnormalities consistent with the posterior reversible encephalopathy syndrome (PRES) (figure). Within 24 hours, visual acuity and eye movements improved, but the patient developed ocular apraxia (increased saccadic latency), optic ataxia (impaired visual navigation), and simultanagnosia (inability to recognize more than a single object): the Balint syndrome (video, second segment). This illustrates that a severe expression of oculomotor apraxia can mimic complete ophthalmoplegia and that Balint syndrome may occur at the onset and during recovery from PRES.
Topics: Brain Diseases; Female; Humans; Magnetic Resonance Imaging; Middle Aged; Occipital Lobe; Ophthalmoplegia; Parietal Lobe; Syndrome
PubMed: 24843035
DOI: 10.1212/WNL.0000000000000441 -
Frontiers in Human Neuroscience 2014
PubMed: 24639641
DOI: 10.3389/fnhum.2014.00123 -
Frontiers in Human Neuroscience 2014Patients with Balint' s syndrome are typically impaired at perceiving multiple objects simultaneously, and at evaluating the relationship between multiple objects in a...
Patients with Balint' s syndrome are typically impaired at perceiving multiple objects simultaneously, and at evaluating the relationship between multiple objects in a scene (simultanagnosia). These deficits may not only be observed in complex scenes, but also when local elements of individual objects must be integrated into a perceptual global whole. Thus, unlike normal observers, patients with simultanagnosia typically show a bias towards the local forms, even to the extent that they cannot identify the global stimuli. However, we have previously shown that global processing is still attainable in Balint patients in certain scenarios (e.g., when local elements are unfamiliar). This suggests that in addition to a possible perceptual deficit that favors the local elements in these patients, impaired attentional control may be at the core of their unique performance. To test this hypothesis we manipulated the perceptual saliency of the local and global elements in a compound letter task so that it included global-more-salient or local-more-salient displays. We show that a Balint patient was able to accurately identify both global and local targets as long as they were the salient aspect of the compound letter. However, substantial impairment was evident when either the global or local elements were the less salient aspect of the compound letter. We conclude that in Balint' s syndrome there is a failure of flexible top-down attention both in biasing attention away from salient irrelevant aspects of the display (salience-based-selection) and in impaired disengagement from irrelevant but salient items once they have been selected.
PubMed: 24578689
DOI: 10.3389/fnhum.2014.00113 -
Experimental Brain Research Apr 2014Bálint syndrome is a combination of severe deficits affecting spatial attention, visuo-motor control and oculomotor function. While the severe restriction of attention...
Bálint syndrome is a combination of severe deficits affecting spatial attention, visuo-motor control and oculomotor function. While the severe restriction of attention (simultanagnosia) and impairments of visually guided reaching have been extensively studied, oculomotor apraxia has received comparatively little attention. The main explanatory hypothesis of oculomotor apraxia is that it is a direct consequence of the severe restriction of attention. Here, we examined in a patient with Bálint syndrome to what extent local image features such as luminance and contrast predict whether a region will be fixated or not. During the viewing of natural photographs, the patient made saccades of very small amplitude, but showed strongly increased fixation duration. In addition, the horizontal and vertical range of fixations was severely restrained compared to control subjects. When analysing the local feature content at fixation, we found that central fixations of the patient contained less local luminance and contrast than fixations of controls while he made fixations to peripheral image regions with disproportionately high luminance and contrast. These findings suggest that while our patient gazes at central regions irrespective of their local feature content, he only looks to the periphery when his gaze is captured by particularly conspicuous features. We propose that oculomotor apraxia in Bálint syndrome reflects a combination of biased representations within a parietal priority map and increased fixational activity due to biased interactions within the oculomotor network.
Topics: Aged; Humans; Male; Photic Stimulation; Psychomotor Disorders; Saccades; Stroke; Syndrome
PubMed: 24449014
DOI: 10.1007/s00221-014-3839-7 -
Frontiers in Human Neuroscience 2013Partial or complete Balint's syndrome is a core feature of the clinico-radiological syndrome of posterior cortical atrophy (PCA), in which individuals experience a...
Partial or complete Balint's syndrome is a core feature of the clinico-radiological syndrome of posterior cortical atrophy (PCA), in which individuals experience a progressive deterioration of cortical vision. Although multi-object arrays are frequently used to detect simultanagnosia in the clinical assessment and diagnosis of PCA, to date there have been no group studies of scene perception in patients with the syndrome. The current study involved three linked experiments conducted in PCA patients and healthy controls. Experiment 1 evaluated the accuracy and latency of complex scene perception relative to individual faces and objects (color and grayscale) using a categorization paradigm. PCA patients were both less accurate (faces < scenes < objects) and slower (scenes < objects < faces) than controls on all categories, with performance strongly associated with their level of basic visual processing impairment; patients also showed a small advantage for color over grayscale stimuli. Experiment 2 involved free description of real world scenes. PCA patients generated fewer features and more misperceptions than controls, though perceptual errors were always consistent with the patient's global understanding of the scene (whether correct or not). Experiment 3 used eye tracking measures to compare patient and control eye movements over initial and subsequent fixations of scenes. Patients' fixation patterns were significantly different to those of young and age-matched controls, with comparable group differences for both initial and subsequent fixations. Overall, these findings describe the variability in everyday scene perception exhibited by individuals with PCA, and indicate the importance of exposure duration in the perception of complex scenes.
PubMed: 24106469
DOI: 10.3389/fnhum.2013.00621 -
Revue Neurologique Oct 2013Progressive visual complaints related to visuospatial disorders, and less often to visuoperceptual disorders, may be the presenting and isolated manifestation of a focal... (Review)
Review
Progressive visual complaints related to visuospatial disorders, and less often to visuoperceptual disorders, may be the presenting and isolated manifestation of a focal degeneration in the posterior cortical areas, called posterior cortical atrophy (PCA). PCA is a clinical syndrome corresponding to a focal variant of Alzheimer's disease in 80% of cases. The predominant dysfunction in the occipitoparietal pathways results in predominant visuospatial disorders, manifesting primarily as dorsal simultanagnosia, alone or associated with other symptoms of Balint's syndrome. PCA is rare and affects young patients who are fully aware of their deficits. Diagnosis of PCA is often delayed, due to insidious onset and development of symptoms, and to poor awareness of the condition in the medical community. An earlier diagnosis requires both better knowledge of PCA among ophthalmologists and neurologists and better recognition of visual complaints, leading to simple bedside tasks that can tackle the syndrome.
Topics: Alzheimer Disease; Atrophy; Biomarkers; Cerebral Cortex; Early Diagnosis; Humans; Perceptual Disorders; Phenotype; Visual Pathways
PubMed: 24035594
DOI: 10.1016/j.neurol.2013.08.001 -
Frontiers in Human Neuroscience 2013In a recent neuroimaging study the comparison of intact vs. disturbed perception of global gestalt indicated a significant role of the temporo-parietal junction (TPJ) in...
In a recent neuroimaging study the comparison of intact vs. disturbed perception of global gestalt indicated a significant role of the temporo-parietal junction (TPJ) in the intact perception of global gestalt (Huberle and Karnath, 2012). This location corresponded well with the areas known to be damaged or impaired in patients with simultanagnosia after stroke or due to neurodegenerative diseases. It was concluded that the TPJ plays an important role in the integration of individual items to a holistic percept. Thus, increased BOLD signals should be found in this region whenever a task calls for the integration of multiple visual items. Behavioral experiments in chess experts suggested that their superior skills in comparison to chess novices are partly based on fast holistic processing of chess positions with multiple pieces. We thus analyzed BOLD data from four fMRI studies that compared chess experts with chess novices during the presentation of complex chess-related visual stimuli (Bilalić et al., 2010, 2011a,b, 2012). Three regions of interests were defined by significant TPJ clusters in the abovementioned study of global gestalt perception (Huberle and Karnath, 2012) and BOLD signal amplitudes in these regions were compared between chess experts and novices. These cross-paradigm ROI analyses revealed higher signals at the TPJ in chess experts in comparison to novices during presentations of complex chess positions. This difference was consistent across the different tasks in five independent experiments. Our results confirm the assumption that the TPJ region identified in previous work on global gestalt perception plays an important role in the processing of complex visual stimulus configurations.
PubMed: 24009574
DOI: 10.3389/fnhum.2013.00513 -
American Journal of Alzheimer's Disease... Sep 2013Alzheimer's disease (AD) is characterized by amnesia, though non-memory-cognitive domains like visual are also affected. We planned to study frequency of visual...
INTRODUCTION
Alzheimer's disease (AD) is characterized by amnesia, though non-memory-cognitive domains like visual are also affected. We planned to study frequency of visual dysfunctions in AD and their relationship with dementia severity.
MATERIALS AND METHODS
This study was conducted in the Cognitive clinic of Department of Neurology, Bangur Institute of Neurosciences, Kolkata, between January 2007 and December 2010. 55 patients of AD were evaluated by neurological and neuropsychological assessments and by special tests for visual dysfunctions.
RESULTS
Common visual dysfunctions were visuo-constructional (87.3%), visuo-perceptual (63.6%), object agnosia(47.3%), prosopagnosia (45.5%), visual hallucination (27.3%) and simultanagnosia (12.7%). Symptoms of ventral visual pathway dysfunction were more common than that of dorsal pathway. MMSE score and number of visual manifestations had a good correlation.
CONCLUSIONS
Visual dysfunctions are common in AD, elicitation of which helps us to understand the cause of disability so that appropriate steps can be taken.
Topics: Aged; Aged, 80 and over; Agnosia; Alzheimer Disease; Ambulatory Care Facilities; Cross-Sectional Studies; Disability Evaluation; Female; Hallucinations; Humans; India; Male; Middle Aged; Neuropsychological Tests; Prosopagnosia; Visual Pathways; Visual Perception
PubMed: 23823144
DOI: 10.1177/1533317513494448 -
Frontiers in Human Neuroscience 2013The parietal cortex is a critical interface for attention and integration of multiple sensory signals that can be used for the implementation of motor plans. Many...
The parietal cortex is a critical interface for attention and integration of multiple sensory signals that can be used for the implementation of motor plans. Many neurons in this region exhibit strong attention-, reach-, grasp- or saccade-related activity. Here, we review human lesion studies supporting the critical role of the parietal cortex in saccade planning. Studies of patients with unilateral parietal damage and spatial neglect reveal characteristic spatially lateralized deficits of saccade programming when multiple stimuli compete for attention. However, these patients also show bilateral impairments of saccade initiation and control that are difficult to explain in the context of their lateralized deficits of visual attention. These findings are reminiscent of the deficits of oculomotor control observed in patients with Bálint's syndrome consecutive to bilateral parietal damage. We propose that some oculomotor deficits following parietal damage are compatible with a decisive role of the parietal cortex in saccade planning under conditions of sensory competition, while other deficits reflect disinhibition of low-level structures of the oculomotor network in the absence of top-down parietal modulation.
PubMed: 23759723
DOI: 10.3389/fnhum.2013.00254