The role of reality monitoring in anosognosia for hemiplegia

Anosognosia for hemiplegia (AHP) refers to a lack of awareness regarding paralysis after stroke. Despite attracting clinical interest for decades, empirical research into AHP has been relatively scarce, and there remains no universally accepted explanation (Jenkinson & Fotopoulou, 2010). This is partially due to difficulty characterising the disorder. The term has been applied to both partial and complete lack of awareness, with partial unawareness presenting as a failure to recognise, appreciate the severity, or acknowledge the consequences of paralysis, and more complete cases involving a failure to admit the presence of a paralysis even after its demonstration (Orfei et al., 2007). The fact that some patients verbally deny their problems, but show behaviours consistent with their paralysis (e.g. executing a bimanual tasks using a unimanual strategy), while others verbally accept their paralysis but behave in a manner inconsistent with this acceptance (e.g. attempting to walk), suggests that verbal and behavioural awareness are independent (Jehkonen et al., 2006). The observation of diverse lesion sites, emotional, perceptual, and cognitive impairments in anosognosia has also resulted in unawareness being considered a multifaceted or multicomponent disorder involving several subtypes (Jehkonen et al., 2006, Orfei et al., 2007, Vocat & Vuilleumier, 2010). As such, different forms of anosognosia may reflect the combination of various deficits, the exact components of which are not currently known (Vocat & Vuilleumier, 2010).