Anosognosia for hemiplegia: test of the personal neglect hypothesis

To test the personal neglect hypothesis of anosognosia for hemiplegia (AHP) using selective anesthesia of the right hemisphere.

Although AHP most commonly follows right-hemisphere injury, the mechanism responsible for this hemispheric asymmetry has not been entirely elucidated. Because denial of ownership of parts on the contralesional side of one's body (personal neglect) also more commonly follows right-hemisphere damage, personal neglect might account for AHP.

AHP and personal neglect were assessed in 20 patients during right intracarotid barbiturate infusion. With vision restricted to the central field, patients were randomly presented with either their own hands or those of examiners matched for size, gender, and race. Patients were asked to read numbers placed on the hands to establish that hemianopia did not confound hand recognition.

All subjects correctly read the numbers on all trials. Only 4 of 20 subjects misidentified their hands and denied awareness of left hemiplegia. All errors occurred for the left hand, indicating personal neglect. However, the 16 subjects without personal neglect also demonstrated AHP.

Because AHP and personal neglect are dissociable, personal neglect cannot completely account for AHP.