The effect of offline anosognosia for hemispatial neglect on neglect rehabilitation in patients with subacute and chronic right hemispheric brain injury. A retrospective cohort study

Is Anosognosia for Left-Sided Hemiplegia Due to a Specific Self-Awareness Defect or to a Poorly Conscious Working Mode Typical of the Right Hemisphere?

“…Two of this survey's findings are at odds with the hypothesis that the right hemisphere might provide a critical contribution to the construction of self-awareness, and rather suggest that anosognosia for hemiplegia might be an instance of the right hemisphere's general tendency to be unaware of disorders provoked by its lesions. The first finding is that a strong relationship can be found not only between right hemisphere lesions and unawareness of hemiplegia (e.g., [10,11,[69][70][71][72][73][74][75][76][77][78][79][80][81]), but also between right hemisphere lesions and anosognosia of other lateralized sensory defects [77,87,88] (e.g., unilateral spatial disorders (e.g., [17,18,[82][83][84][85][86]) and emotional disorders (e.g., [19,20]). The second finding is that when the incidence of unawareness of hemiplegia and of unilateral neglect in studies that investigated these two forms of anosognosia in the same patients were compared, anosognosia was associated more with attentional rather than motor disorders.…”

“…The first difficulty encountered using these search criteria was a numerical discrepancy between the large number of studies that had assessed the frequency of anosognosia for hemiplegia and the small number of studies that had taken into account the frequency of unawareness of unilateral spatial neglect. I identified 15 studies [10,11,[69][70][71][72][73][74][75][76][77][78][79][80][81] that had investigated anosognosia for hemiplegia and 7 [17,18,[82][83][84][85][86] that had assessed anosognosia for extrapersonal neglect for a large number of patients. This difference was probably due the fact that it is much simpler to clinically detect a discrepancy between the objective and the subjective evaluation of hemiplegia than it is to detect a similar discrepancy in the evaluation of unilateral neglect.…”

“…This interpretation was confirmed by the observation that most studies that investigated the frequency of anosognosia for hemiplegia in a large number of right and left brain-damaged patients were published in the second half of the last century, whereas most studies that assessed the frequency of unawareness of unilateral neglect were published much more recently. For instance, the three investigations that studied the incidence of anosognosia for hemiplegia in the highest number of unilateral brain-damaged patients were published in 1952 by Nathanson et al [69], in 1976 by Green and Hamilton [70] and in 1978 by Cutting [71], whereas the study that investigated the highest number of patients with anosognosia for unilateral neglect was published in 2023 by Karataş et al [86]. A second methodological difficulty was that even if lesions due to stroke were most frequently reported in studies of anosognosia for hemiplegia and of unawareness of unilateral neglect, these lesions and their localization could be heterogeneous.…”

“…The final methodological problem was that the aim of some reviewed investigations was not to evaluate the incidence of these forms of anosognosia in patients with lesions of the right or left hemisphere, but to evaluate the impact of these types of disease unawareness on functional outcome or discharge from the hospital (e.g., [76,80,85,86]). Therefore, such studies did not take into account the relationship between incidence of anosognosia and the side of brain in which the lesion occurred, but only the relationship between the presence of anosognosia and the functional outcome or discharge from the hospital within a given time limit.…”