Anosognosia for hemiplegia after stroke is a multifaceted phenomenon: a systematic review of the literature

Abstract

Anosognosia is the lack of awareness or the underestimation of a specific deficit in sensory, perceptual, motor, affective or cognitive functioning due to a brain lesion. This self-awareness deficit has been studied mainly in stroke hemiplegic patients, who may report no deficit, overestimate their abilities or deny that they are unable to move a paretic limb. In this review, a detailed search of the literature was conducted to illustrate clinical manifestations, pathogenetic models, diagnostic procedures and unresolved issues in anosognosia for motor impairment after stroke. English and French language papers spanning the period January 1990-January 2007 were selected using PubMed Services and utilizing research words stroke, anosognosia, awareness, denial, unawareness, hemiplegia. Papers reporting sign-based definitions, neurological and neuropsychological data and the results of clinical trials or historical trends in diagnosis were chosen. As a result, a very complex and multifaceted phenomenon emerges, whose variable behavioural manifestations often produce uncertainties in conceptual definitions and diagnostic procedures. Although a number of questionnaires and diagnostic methods have been developed to assess anosognosia following stroke in the last 30 years, they are often limited by insufficient discriminative power or a narrow focus on specific deficits. As a consequence, epidemiological estimates are variable and incidence rates have ranged from 7 to 77% in stroke. In addition, the pathogenesis of anosognosia is widely debated. The most recent neuropsychological models have suggested a defect in the feedforward system, while neuro-anatomical studies have consistently reported on the involvement of the right cerebral hemisphere, particularly the prefrontal and parieto-temporal cortex, as well as insula and thalamus. We highlight the need for a multidimensional assessment procedure and suggest some potentially productive directions for future research about unawareness of illness.

Vestibular stimulation attenuates unrealistic optimism

“…We speculate that anosognosia stems, at least in part (Orfei et al, 2007;Aimola Davies et al, 2009), from damage to a region of the brain that integrates undesirable information, and that vestibular stimulation abolishes anosognosia by restoring or augmenting this specific processing function. Converging evidence from lesion studies of anosognosia (Berti et al, 2005) and from fMRI investigations of unrealistic optimism and vestibular stimulation (Lobel et al, 1998;Fasold et al, 2002) implicates the pars opercularis in right IFG as the region in question.…”

Assessing anosognosia: a critical review

“…Horizontal line indicates the cut-off score of 7 (Crawford et al, 2006) 2010). Lack of consensus amongst researchers and clinicians about the methods of assessment results in difficulties in comparing findings across different studies (Vuilleumier, 2000;2004;Adair et al, 2003;Baier & Karnath, 2005;Jehkonen et al, 2006;Vallar & Ronchi, 2006;Orfei et al, 2007;Jenkinson et al, 2011), and it may have produced contrasting findings (Cocchini & Della Sala, 2010). It seems indeed likely that while similar mechanisms may underlie anosognosia for different deficits, different causes may determine anosognosia for a specific deficit.…”

“…This is what we will refer to as "explicit anosognosia". The most common diagnostic tools are structured interviews and self-evaluation questionnaires (e.g., Jehkonen et al, 2006;Orfei et al, 2007Orfei et al, , 2010a; also summarised in Table 1). …”

“…The reported frequency of anosognosia following brain damage varies considerably across studies, ranging from 7% to 77% (Orfei et al, 2007; see also Jehkonen et al, 2006). This variability may be due to different diagnostic criteria (Baier & Karnath, 2005) or to recruitment of patients at different post-onset intervals.…”

“…However, reviews of the literature have shown that chronic anosognosia is not as rare as textbooks suggest (see Table 1 in Cocchini et al, 2002;Orfei et al, 2007;Jehkonen et al, 2006), and several studies have pointed out how lack of awareness can seriously interfere with functional recovery and rehabilitation training (Gialanella & Mattioli, 1992;Maeshima et al, 1997;Hartman-Maeir et al, 2001;Hartman-Maeir et al, 2002;Appelros et al, 2002;Gialanella, et al, 2005;Di Legge et al, 2005).…”