Incidence and diagnosis of anosognosia for hemiparesis revisited

BACKGROUND: In previous studies, the incidence of anosognosia for hemiparesis has varied between 17% and 58% in samples of brain damaged patients with hemiparesis. OBJECTIVE: To determine whether this wide variation might be explained by the different criteria used for diagnosing anosognosia. METHODS: 128 acute stroke patients with hemiparesis or hemiplegia were tested for anosognosia for hemiparesis using the anosognosia scale of Bisiach et al. RESULTS: 94% of the patients who were rated as having "mild anosognosia"-that is, they 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. Their other deficits clearly had a greater impact. These patients had significantly milder paresis than those who denied their disorder even when asked directly about their limbs. CONCLUSIONS: Patients who do not mention their paresis spontaneously but do so when questioned about it directly should not be diagnosed having "anosognosia." If this more conservative cut off criterion is applied to the data of the present as well as previous studies, a frequency of between 10% and 18% for anosognosia for hemiparesis is obtained in unselected samples of acute hemiparetic stroke patients. The incidence thus seems smaller than previously assumed.