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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an attempt to resolve contradictory reports about the effect of right-versus left-hemisphere damage on perception of the Mueller-Lyer illusion, the present study examined judgments of stroke patients using this and several other visual illusions. The results provide some indication of abnormal perception of the Mueller-Lyer by patients with left-hemisphere damage. But the overall magnitude of illusion was normal in both groups of patients. It is possible that stroke damage did not affect the brain areas that are responsible for "gestalt" synthesis. However other recent studies using the Mueller-Lyer suggest that actual or incipient eye movements play an important role in the perception of this illusion, and under some conditions of testing, it is the activity of the left hemisphere that determines illusion magnitude.
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PMID:The influence of stroke on visual illusion magnitude. 57 63

We have studied 97 patients with dementia who have been discharged from our hospital and 106 inpatients with dementia who have been admitted during last two years in our hospital. The diagnosis of dementia was done according to the criteria of DSM-III. Based on their clinical course, neurological signs, Hachinski's ischemic score and neuroradiological findings, we divided patients into 4 groups, [senile dementia of the Alzheimer type (SDAT), vascular dementia (VD), unclassified dementia and other dementias which includes dementia with Parkinson's disease or motor neuron disease, etc.]. Concerning 70 demented patients who died during hospitalization, the average age of onset and the duration of illness of SDAT were 80.5 years old and 4.6 years respectively and those of VD were 77.6 years old and 2.7 years respectively. The common causes of death were pneumonia (50%) and cardiac failure (24%). Recurrence of cerebral vascular accident (CVA) was also another frequent cause of death in VD. The most common behavioral problems causing admission in patients of SDAT were aimless wandering, nocturnal delirium, illusion and hallucination. In VD, nocturnal delirium, aimless wandering, violence and abnormal monologue were most common causes of admission. The important causes degrading ADL of inpatients were fracture, especially fracture of the hip joint, pneumonia, intestinal bleeding and CVA. Concerning the increase of the population of over 75 years old, it will be suggested that the care and treatment of demented patients in this age group will become a major social problem.
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PMID:[Clinical and epidemiological studies on inpatients with dementia]. 238 92

One hundred four patients with a unilateral right hemispheric lesion, consecutively admitted to a rehabilitation clinic, were examined to evaluate: 1. the incidence of patients with severe hemineglect at least two months after the CVA; 2. the role of the length of time from the onset of disease in predicting the severity of the disorder. Estimates of the disorder varied according to the test used, ranging from 26.7% to 52.0%. On the basis of an overall clinical judgment, approximately 20% of patients had very severe hemineglect. Consistent with earlier findings, the severity of the disorder was unrelated to the duration of the disease when examined by means of correlational analyses. However, a subdivision of patients into subgroups according to the length of time from the onset of the disease showed a trend for a moderate reduction of the severity of the deficit starting from the 3-month subgroup for two tests (Barrage Test and Wundt-Jastrow Area Illusion Test).
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PMID:Incidence and evolution of the hemineglect disorder in chronic patients with unilateral right brain damage. 280 60

When two similar pictures, overlapping but slightly displaced, were projected on a screen in alternation, apparent movement could be seen. How similar must successive pictures be to give apparent movement? This is the 'correspondence problem'. Manipulations of the local and global correspondences between pictures included motion phenomena such as reversed apparent movement; a four-stroke oscillatory cycle which gave an illusion of continuous motion in one direction; edges defined by texture, stereoscopic depth, or flicker, kinetic edges; and wave motion. It was concluded that human motion perception may comprise two separate mechanisms. Local point-by-point correlations between pictures are detected by a relatively peripheral system, probably based on directonally selective neural units. More subtle global correspondences are analysed by a more cognitive system which extracts edges before it process motion.
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PMID:The perception of apparent movement. 610 35

Visual illusions and hallucinations may accompany a wide variety of disorders with many different aetiologies; therefore, they are non-specific phenomena. Lesions in the visual pathway may be associated with visual misperceptions. In these cases more exact information about the misperceptions--whether they are monocular or binocular, present in the whole visual field or a hemifield--may contribute to diagnostic accuracy and to a more comprehensive understanding of the patient and his state of mind. Illusions such as perseveration, monocular diplopia and polyopia, and dysmorphopsia may also occur in healthy individuals, but they are found most often in patients with epilepsy, migraine and stroke. These phenomena do not permit exact localization and definition of an aetiology, but lesions in the occipital and occipitotemporal regions near the visual pathway are involved in most cases. Hallucinations always represent a pathological form of perception. They are classified as unformed (photopsias) or formed (complex). Photopsias may be described in terms of colour, shape and brightness. Their wide variety makes it difficult, if not impossible, to arrive at an exact description of their aetiology, but it is possible to define their anatomical origin in some cases. Complex hallucinations suggest an occipitotemporal locus. Whether they appear in the whole visual field or in the hemifield may prove decisive in determining pathogenesis. A number of characteristics permit a rough classification of these phenomena. Complex hallucinations accompany physical illness and are susceptible to psychodynamic interpretation.
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PMID:Visual illusions and hallucinations. 813 1

Touching warm and cool bars that are spatially interlaced produces a painful burning sensation resembling that caused by intense, noxious cold. We demonstrated previously that this thermal grill illusion can be explained as an unmasking phenomenon that reveals the central inhibition of pain by thermosensory integration. In order to localize this unmasking in the human brain, we have used positron emission tomography (PET) to compare the cortical activation patterns evoked by the thermal grill and by cool, warm, noxious cold and noxious heat stimuli. The thermal grill illusion produces activation in the anterior cingulate cortex, whereas its component warm and cool stimuli do not. This area is also activated by noxious heat or cold. Thus, increased activity in the anterior cingulate cortex appears to be selectively associated with the perception of thermal pain. Disruption of thermosensory and pain integration may account for the central pain syndrome that can occur after stroke damage.
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PMID:Functional imaging of an illusion of pain. 891 69

Under normal circumstances, information from a number of sources is combined to compute a unitary percept of the body. However, after pathology these influences may be perceived simultaneously, resulting in multiple dissociated conscious representations. In a recent paper, we described subject E.P., a right-handed female stroke patient with a right frontomesial lesion who sporadically experiences a supernumerary 'ghost' left arm that occupies the previous position of the real left arm after a delay of 60-90 s. We used a delayed response paradigm with functional MRI to examine the haemodynamic correlates of E.P.'s illusion. Comparison of periods of time during scanning when the ghost arm was present against when it was not revealed a single cluster (9 voxels, t = 5.11, P < 0.012 corrected for multiple comparisons) located on the right medial wall in the supplementary motor area ('SMA proper'). Our results suggest that areas traditionally classified as part of the motor system can influence the conscious perception of the body. We propose that, as a consequence of her injury, E.P. is aware of the position of the phantom limb in this 'action space' while also continuing to be aware of the true position of her real limb on the basis of afferent somatosensory information.
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PMID:Whose arm is it anyway? An fMRI case study of supernumerary phantom limb. 1202 15

The room tilt illusion is a transient misperception of the visual image as tilted on its side or even upside down; in this case it has been termed acute upside down reversal of vision. We report on two cases of room tilt illusion as manifestation of VIII nerve neuritis (herpes-zoster infection) and cerebellar hemorrhage. Room tilt illusion has been reported in association with vertebrobasilar stroke, migraine, multiple sclerosis, epilepsy and labyrinthine disorders. The pathophysiology of this rare visual illusion has been related to a lesion of the visual or vestibulo-otolith pathways. In animals the neurones of the parieto-insular vestibular cortex areas are multisensory. So, they can respond to somatosensory, optokinetic and visual stimuli. In humans the knowledge about vestibular cortex function and localization is less precise than in animals. However, we propose a disorder of multisensorial vestibular cortex, resulting from a lession of vestibular pathways or association cortex, as mechanism of this phenomenon.
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PMID:[Room tilt illusion: Report of two cases and terminological review]. 2116 31

Most people see movement in Figure 1, although the image is static. Motion is seen from black --> blue --> white --> yellow --> black. Many hypotheses for the illusory motion have been proposed, although none have been tested physiologically. We found that the illusion works well even if it is achromatic: yellow is replaced with light gray, and blue is replaced with dark gray. We show that the critical feature for inducing illusory motion is the luminance relationship of the static elements. Illusory motion is seen from black --> dark gray --> white --> light gray --> black. In psychophysical experiments, we found that all four pairs of adjacent elements when presented alone each produced illusory motion consistent with the original illusion, a result not expected from any current models. We also show that direction-selective neurons in macaque visual cortex gave directional responses to the same static element pairs, also in a direction consistent with the illusory motion. This is the first demonstration of directional responses by single neurons to static displays and supports a model in which low-level, first-order motion detectors interpret contrast-dependent differences in response timing as motion. We demonstrate that this illusion is a static version of four-stroke apparent motion.
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PMID:Neural basis for a powerful static motion illusion. 1594 93

Treatment with a mirror gives an illusion of function in a missing or non-functioning hand. The method is based on the concept that the central representation of phantoms and body image can change rapidly, and has been described in the treatment of phantom pain and stroke. We show in three pilot cases new applications for the use of the mirror in rehabilitation after hand surgery.
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PMID:Training with a mirror in rehabilitation of the hand. 1601 38


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