Anosognosia

Conclusions

Based on our work, primarily using the Wada procedure, we have not identified a single mechanism that can entirely account for anosognosia for hemiplegia. Certainly, for psychological reasons, people do deny disabilities; however, this hypothesis cannot explain why anosognosia of hemiplegia is more frequently associated with right- than with left-hemisphere dysfunction. It also cannot explain why patients may be aware of one deficit such as aphasia and be unaware of another deficit such as a hemiparesis. We also provided evidence that some patients with anosognosia may improve when feedback is improved by moving the paretic hand into the right body hemispace and the right visual field. Therefore, the lack of feedback from both sensory defects and spatial neglect may also play a role ön anosognosia. If patients do not recognize that an extremity belongs to them, they certainly will not recognize that there is a deficit, and asomatognosia may be another important factor in anosognosia. When deprived of feedback, some patients with a left hemiparesis feel that they are moving their paralyzed arm. However, this phantom movement is only rarely associated with anosognosia. Although right-hemisphere dysfunction may induce a confusional state, many patients with anosognosia are without confusion. The isolated left hemisphere may confabulate, but confabulation and hemispheric disconnection appear to play only a minor role in anosognosia. People must have the intention to move and develop expectations before they can discover that there is a failure to move. Some patients may be unaware of their failure to move because they do not try to move. We again suspect that this explanation of anosognosia cannot be the entire explanation. Based on our studies of anosognosia for hemiplegia we would suggest that normal self-awareness depends on several parallel processes. We must have feedback systems that allow us to monitor our body and be able to attend to different parts of space and to our own bodies. We must develop accurate representations of our body, arid these representations must be continuously modified by both expectations and knowledge of results.