What is Mine? Behavioral and Anatomical Dissociations between Somatoparaphrenia and Anosognosia for Hemiplegia

We describe the clinical manifestations and the lesion patterns of five patients with somatoparaphrenia, the denial of ownership for a paralyzed limb, who showed the rare dissociation from anosognosia for hemiplegia. Similar cases have been only occasionally cited in the literature with scanty descriptions of their symptoms and no detailed anatomical assessment. All patients had extrapersonal and at least mild personal neglect. The lesions pattern was mainly subcortical, with a significant involvement of the right thalamus, the basal ganglia and the internal capsule. A formal comparison between the anatomical pattern previously associated with anosognosia in a study performed in 2005 by Berti and colleagues, and the lesion distribution of each patient clearly shows that our pure somatoparaphrenic patients had a sparing of most of the regions associated with anosognosia for hemiplegia. The behavioral dissociation between SP and anosognosia for hemiplegia, together with this new anatomical evidence, suggests that motor awareness is not sufficient to build up a sense of ownership and therefore these two cognitive abilities are at least in part functionally independent and qualitatively different.