Unawareness of deficits after right hemisphere stroke : double-dissociations of anosognosias

The aim was to study whether anosognosia for hemiparesis, anosognosia for neglect and general unawareness of illness double-dissociate, indicating that anosognosias are specific and independent impairments of awareness. On the other hand, anosognosias may be associated with one another and with general cognitive dysfunction, which decreases awareness of deficits. The persistence and predictive value of anosognosias was examined during a 1-year follow-up. Fifty-seven consecutive patients with acute right hemisphere infarction underwent neurological and neuroradiological examinations, neuropsychological testing and an interview 10 days, 3 months and 1 year after onset. Anosognosia for neglect and anosognosia for hemiparesis double-dissociated, as did unawareness of illness and anosognosia for neglect. Patients showing unawareness of illness or anosognosia for neglect and anosognosia for hemiparesis had poorer orientation and verbal memory than patients who were aware of these defects. Unawareness of illness and anosognosia for hemiparesis disappeared during 3-month follow-up. Double-dissociations demonstrate that anosognosias for different defects are independent and specific impairments of awareness, although general cognitive disorder may also reduce awareness of defects. Unawareness of illness and anosognosia for hemiparesis disappear rapidly and can hardly be direct causes of poor long-term recovery. However, transient anosognosia may be associated with persistent disorders which result in poor outcome.