[Double dissociation between unilateral neglect and anosognosia]. / Double dissociation entre négligence unilatérale gauche et anosognosie.

We report two patients presenting with a subacute right hemisphere stroke. These cases demonstrate a double dissociation between unilateral neglect and anosognosia for hemiplegia. The first patient suffered from a severe left hemiplegia associated with severe and persisting unilateral neglect. He appeared fully aware of his motor impairment. The second patient had a severe left hemiplegia, without any major sign of unilateral neglect on clinical tests nor on behavioural assessment. Nevertheless, he presented a severe and sustained anosognosia for hemiplegia. These case reports support the assumption that anosognosia and unilateral neglect, although they are frequently associated, may rely on independent mechanisms.

Sensitivity of clinical and behavioural tests of spatial neglect after right hemisphere stroke.

OBJECTIVES: The lack of agreement regarding assessment methods is responsible for the variability in the reported rate of occurrence of spatial neglect after stroke. The aim of this study was to assess the sensitivity of different tests of neglect after right hemisphere stroke. METHODS: Two hundred and six subacute right hemisphere stroke patients were given a test battery including a preliminary assessment of anosognosia and of visual extinction, a clinical assessment of gaze orientation and of personal neglect, and paper and pencil tests of spatial neglect in the peripersonal space. Patients were compared with a previously reported control group. A subgroup of patients (n=69) received a behavioural assessment of neglect in daily life situations. RESULTS: The most sensitive paper and pencil measure was the starting point in the cancellation task. The whole battery was more sensitive than any single test alone. About 85% of patients presented some degree of neglect on at least one measure. An important finding was that behavioural assessment of neglect in daily life was more sensitive than any other single measure of neglect. Behavioural neglect was considered as moderate to severe in 36% of cases. A factorial analysis revealed that paper and pencil tests were related to two underlying factors. Dissociations were found between extrapersonal neglect, personal neglect, anosognosia, and extinction. Anatomical analyses showed that neglect was more common and severe when the posterior association cortex was damaged. CONCLUSIONS: The automatic rightward orientation bias is the most sensitive clinical measure of neglect. Behavioural assessment is more sensitive than any single paper and pencil test. The results also support the assumption that neglect is a heterogeneous disorder.