Abstract
The present study investigated the incidence and diagnosis as well as the analysis of lesion location of stroke patients with anosognosia for hemiparesis or hemiplegia. These patients typically are convinced that their limbs function normally although they have obvious motor defects. Such patients may experience the paretic limbs as strange or as not belonging to them, or even attribute ownership to another person and try to push their paralyzed limb out of bed. In previous studies, the incidence of anosognosia for hemiparesis varied between 17% and 58% in samples of brain damaged patients with hemiparesis. One explanation for this wide variation might be different criteria used for the diagnosis of anosognosia. The sample of the present study consisted of 128 acute stroke patients with hemiparesis or hemiplegia. The patients were tested for anosognosia for hemiparesis using the anosognosia scale of Bisiach et al. (1986). Analysis revealed that 94% of those patients rated having 'mild anosognosia', i.e. who did not acknowledge their hemiparesis spontaneously following a general question about their complaints, suffered from and mentioned other neurological deficits, such as dysarthria, ptosis, or headache. However, they immediately acknowledged their paresis when they were asked about the strength of their limbs. Obviously other deficits had a higher impact for these subjects. In fact, they had significantly milder paresis compared to patients who denied their disorder even when asked about their limbs. The data suggest that patients who do not mention their paresis spontaneously, but directly when addressed by the examiner should not be diagnosed having 'anosognosia'. If this more conservative cut-off criterion is applied to the data of the present as well as of previous studies, a frequency between 10% and 18% for anosognosia for hemiparesis is obtained in unselected samples of acute, hemiparetic stroke patients. The incidence of anosognosia for hemiparesis thus seems to be less frequent than previously assumed. Previous studies have favored the idea that anosognosia for hemiparesis is related to disturbed right hemisphere processes. Here we present data supporting the hypothesis that the key area typically associated with anosognosia for hemiparesis/-plegia is the right posterior insula. Neuronal responses in monkeys suggested that this region represents a somatosensory as well as a motor association area. Obviously signal processing in the insular cortex plays a crucial part for the generation of self-awareness and our beliefs about function of body parts.
Author and committee
dc:creator, dc:contributor.*- Author
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- Baier, Bernhard
Identifiers
dc:identifier.*- Identifier
- hdl:10900/44577