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Query: UMLS:C0018991 (hemiplegia)
 3,997 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present paper, we shall review clinical evidence and theoretical models related to anosognosia for sensorimotor impairments that may help in understanding the normal processing underlying conscious self-awareness. The dissociations between anosognosia for hemiplegia and anosognosia for hemianaesthesia are considered to give important clinical evidence supporting the hypothesis that awareness of sensory and motor deficits depends on the functioning of discrete self-monitoring processes. We shall also present clinical and anatomical data on four single case reports of patients selectively affected by anosognosia for hemianaesthesia. The differences in the anatomical localization of lesions causing anosognosia for hemiplegia and anosognosia for hemianaesthesia are taken as evidence that cerebral circuits subserving these monitoring processes are located in separate brain areas, which may be involved both in the execution of primary functions and the emergence of awareness related to the monitoring of the same functions. The implications of these findings for the structure of conscious processes shall be also discussed.
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PMID:Modular structure of awareness for sensorimotor disorders: evidence from anosognosia for hemiplegia and anosognosia for hemianaesthesia. 1828 Oct 65

The sense of embodiment is vital for self recognition. An examination of anosognosia for hemiplegia--the inability to recognise that one is paralysed down one side of one's body--suggests the existence of 'online' and 'offline' representations of the body. Online representations of the body are representations of the body as it is currently, are newly constructed moment by moment and are directly "plugged into" current perception of the body. In contrast, offline representations of the body are representations of what the body is usually like, are relatively stable and are constructed from online representations. This distinction is supported by an analysis of phantom limb--the feeling that an amputated limb is still present--phenomena. Initially it seems that the sense of embodiment may arise from either of these types of representation; however, an integrated representation of the body seems to be required. It is suggested information from vision and emotions is involved in generating these representations. A lack of access to online representations of the body does not necessarily lead to a loss in the sense of embodiment. An integrated offline representation of the body could account for the sense of embodiment and perform the functions attributed to this sense.
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PMID:Types of body representation and the sense of embodiment. 1872 92

Brain edema after cardiac surgery is unusual and often asymptomatic. We encountered a 34-year-old man who had postoperative left flaccid hemiplegia and anosognosia after undergoing composite root replacement and closure of a patent foramen ovale. Computed tomographic and magnetic resonance imaging (MRI) scans showed profound white matter changes indicative of brain edema predominantly in the right hemisphere. His symptoms resolved spontaneously within 3 days with resolution of MRI abnormality. No evidence of cerebral infarction was documented on diffusion-weighted imaging and apparent diffusion coefficient mapping, or on the follow-up MRI obtained 25 days after presentation. The cause for the unilateral brain edema is unknown, but the patient's clinical course and imaging are supportive for a variant of a hyperperfusion syndrome or reversible encephalopathy. The outcome was excellent.
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PMID:Reversible unilateral brain edema presenting with major neurologic deficit after valve repair. 1864 Mar 46

Accounts of anosognosia for hemiplegia have long suggested some implicit knowledge of deficit, where lack of awareness is driven by the emotionally-aversive consequences of bringing deficit-related thoughts to consciousness. The present study investigates this issue using an attentional-capture paradigm, presenting words associated with hemiplegia-related deficit. As anticipated, non-anosognosics showed reduced latencies (i.e., facilitation) for emotionally threatening words. In striking contrast, anosognosics showed increased latencies (i.e., interference), a finding which supports the claim of implicit awareness. The effect appears to be due to newly-learned associations to disability-related words: where anosognosics show a pattern of performance previously described as repression.
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PMID:Attention and emotion in anosognosia: evidence of implicit awareness and repression? 1878 43

Recent theories propose that anosognosia for hemiplegia (AHP) results from specific impairments in motor planning. However, no study has hitherto directly investigated the role of motor intention in the observed non-veridical awareness of action in AHP. We developed the following paradigm to investigate the role of motor planning in awareness in patients with AHP: Four hemiplegic patients with and four without anosognosia were provided with false visual feedback of movement in their left paralysed arm through a prosthetic rubber hand. We examined whether the ability to detect presence or absence of movement based on visual evidence varied according to whether the patient had planned to move their limb or not. Motor intention had a selective effect on patients with AHP; they were more likely than controls (U = 16, P < 0.001) to ignore the visual feedback of a motionless hand and claim that they moved it when they had the intention to do so (self-generated movement) than when they expected an experimenter to move their own hand (externally generated movement), or there was no expectation of movement. By contrast, patients without AHP were not influenced by these manipulations, and did not claim they moved their hand when the hand remained still. This is the first direct demonstration that altered awareness of action in AHP reflects a dominance of motor intention prior to action over sensory information about the actual effects of movement.
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PMID:The role of motor intention in motor awareness: an experimental study on anosognosia for hemiplegia. 1881 42

Anosognosia for hemiplegia (AHP) is characterised by poor insight or underestimation of hemiplegia after brain injury. Recent explanations of AHP have used an established 'forward model', which proposes that normal motor awareness involves comparing the predicted and actual sensory consequences of movements. These accounts propose that AHP patients may be able to form representations of their intended movements (i.e., motor representations), but fail to register discrepancy between intended and actual movements. A prediction arising from this proposal is that AHP patients are able to generate motor representations involving their hemiplegic limb(s). Our study provides the first direct examination of this prediction in patients with AHP. We used an existing 'grip selection task', which investigates motor representations by comparing how patients would grasp an object and how they actually grasp the same object. Eight right hemisphere stroke patients with AHP, 10 control patients (non-AHP), and 22 age-matched healthy volunteers (HVs) completed the task. Results showed that HVs outperformed both AHP and non-AHP patients in their motor representations for the hemiplegic limb; however, the performance of AHP and non-AHP patients did not differ significantly. Motor representations for the intact limb were lower than normal in AHP patients, whereas performance in non-AHP patients was midway between the AHP and HV groups. Findings suggested that the ability to form motor representations lie on a continuum, but that impaired motor representations for the paralysed limb cannot account for AHP. Distorted motor representations, in combination with other deficits, might contribute to the pathogenesis of AHP.
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PMID:Imagining the impossible: motor representations in anosognosia for hemiplegia. 1897 67

Anosognosia for hemiplegia (AHP) is a lack of awareness about paralysis following stroke. Recent explanations use a 'forward model' of movement to suggest that AHP patients fail to register discrepancies between internally- and externally-generated sensory information. We predicted that this failure would impair the ability to recall from memory whether information is internally- or externally-generated (i.e., reality monitor). Two experiments examined this prediction. Experiment 1 demonstrated that AHP patients exhibit a reality monitoring deficit for non-motor information (i.e., perceived vs. imagined drawings), whilst hemiplegic controls without anosognosia (nonAHP) perform like age-matched healthy volunteers (HVs). Experiment 2 explored if this deficit occurs when AHP patients discriminate performed, imagined, or observed movement. Results showed impaired reality monitoring for movements in AHP and nonAHP patients relative to HVs. Findings suggest that reality monitoring processes not directly related to movement, together with a failure to reality monitor movements, contribute to the pathogenesis of AHP.
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PMID:Reality monitoring in anosognosia for hemiplegia. 1919 10

We report a patient with severe anosognosia for hemiplegia, who recovered instantly and permanently when viewing herself in a video replay. We believe the observed dramatic reinstatement of the patient's awareness related to her self-observation 'from the outside' (3rd person perspective) and 'off-line' (at a time later than the actual attempt to execute a movement); her anosognosia had been unaltered when she observed her plegic arm in her ipsilateral visual field (self-observation from a 1st-person perspective and 'on-line'). To our knowledge, the role of self-observation in videos or mirrors has not being assessed in AHP to date. Our study provides preliminary evidence that, when right hemisphere damage impairs the ability to update one's body representation, judgements relying on 3rd-person and off-line self-observation may be spared in some patients and may facilitate 1st person awareness.
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PMID:Self-observation reinstates motor awareness in anosognosia for hemiplegia. 1942 88

Anosognosia for hemiplegia (AHP) is the apparent inability to acknowledge contralesional paralysis, typically following right-hemisphere lesions. Here, we review studies that regard AHP as a specific deficit of motor awareness and explain its symptoms by employing an established computational model of motor control. These accounts propose that AHP arises from a breakdown in the monitoring of intended and actual movement. First, we critically examine physiological and behavioural experiments, which attempt to provide an account of AHP by verifying the presence or absence of motor intentions. We then review more recent experiments that endeavour to empirically address the hitherto unexplored role of motor intentions and internal representations of movements in AHP patients' non-veridical (illusory) awareness of movement. Finally, we consider implications of AHP research for clinical practice and the understanding of motor awareness more generally. We conclude that the false experience of movement in AHP may provide insight into what occurs when the mechanism responsible for monitoring and correcting significant discrepancies between predicted and executed actions is impaired. The system seems to continue to operate by deceiving awareness.
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PMID:Motor awareness in anosognosia for hemiplegia: experiments at last! 1959 52

This article highlights the latest findings regarding the cognitive-behavioral syndromes of neglect and anosognosia for hemiplegia that occur following right hemisphere stroke. We review papers published in the past 2 years pertaining to neurophysiology, assessment, and intervention for these two syndromes.
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PMID:Recent advances in the understanding of neglect and anosognosia following right hemisphere stroke. 1981 33


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