The Neural Basis of Anosognosia for Spatial Neglect
Simone Vossel, PhD; Peter H. Weiss, MD; Philipp Eschenbeck, PhD; Jochen Saliger;
Hans Karbe, MD; Gereon R. Fink, MD
Background and Purpose—The present study investigated the lesion anatomy of anosognosia for visuospatial neglect
resulting from right hemispheric stroke.
Methods—In 63 patients, self-ratings of performance in paper-and-pencil tests were contrasted with external performance
ratings. Lesion analysis was conducted on patient subgroups with different degrees of anosognosia but comparable
Results—Independent of the severity of visuospatial neglect per se, damage to the right angular and superior temporal
gyrus was associated with higher levels of anosognosia.
Conclusions—Using a novel assessment of anosognosia for spatial neglect, the present study relates stroke-induced
self-awareness deficits to inferior parietal and superior temporal brain damage. (Stroke. 2012;43:1954-1956.)
Key Words: lesion analysis ? neglect ? self-awareness
deficits, that is, show anosognosia.1Previous studies demon-
strated that the majority of patients with reduced self-awareness
for hemiplegia/hemiparesis have right hemispheric brain dam-
age.2,3No study has yet focused on the lesion anatomy of
self-awareness deficits for visuospatial neglect, although these
are even more prevalent than for hemiplegia.4The present study
investigated anosognosia for spatial neglect and its neuroanato-
my in patients with different degrees of impaired self-awareness
but comparable visuospatial impairment.
espite the severe impact of stroke-induced impairments
on daily life, some patients remain unaware of their
Patients and Methods
Sixty-three patients with unilateral right hemispheric stroke (22
females) and 18 healthy control subjects (7 females) gave written
informed consent. Lesions were confirmed by CT or MRI. The study
had been approved by the local ethics committee.
Participants performed 6 paper-and-pencil tests from the
Behavioral Inattention Test5(star and line cancellation, line
bisection, figure copying, clock drawing, text reading). Subse-
quent to each subtest, the patients rated their performance on a
5-point scale (ranging from 1, severe difficulties to 5, no
difficulties). An equivalent rating was performed by one of the
investigators (P.E.) to evaluate the patient’s difficulties during
task performance. This external rating was moreover used to
relate the patients’ performance to that of healthy control subjects
(patients performing ?3 SDs below the mean of control subjects
were regarded to have substantial visuospatial deficits; Table 1).
Interrater agreement with 2 additional raters (evaluating the
performance of 39 patients who gave their consent to video
recordings) and correlations with objective performance measures
(line bisection deviation and cancellation laterality quotients)
were determined to ensure the reliability and validity of the
To quantify the degree of unawareness for visuospatial neglect,
the following index was calculated:
Table 1.Descriptive Data (Mean?SD)
Healthy elderly control subjects (n?18)
Patients performing within 3 SDs from
control subjects (n?34)
Patients performing ?3 SDs below
control subjects (n?22)*
. . .29.3?0.96
*Note that only patients with matching pair member (ie, included in the lesion analyses) are listed.
Received March 12, 2012; final revision received April 5, 2012; accepted April 6, 2012.
From the Cognitive Neuroscience, Institute of Neuroscience & Medicine (INM-3; S.V., P.H.W., P.E., G.R.F.), Research Centre Ju ¨lich, Ju ¨lich,
Germany; the Department of Neurology (P.H.W., G.R.F.), University Hospital Cologne, Cologne, Germany; Hochschule fu ¨r Gesundheit (P.E.),
University of Applied Sciences, Bochum, Germany; and the Neurological Rehabilitation Centre Godesho ¨he (J.S., H.K.), Bonn, Germany.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.112.
Correspondence to Simone Vossel, PhD, Institute of Neuroscience and Medicine (INM-3), Research Centre Ju ¨lich, Leo-Brandt-Str 5, 52425 Ju ¨lich,
Germany. E-mail email@example.com
© 2012 American Heart Association, Inc.
Stroke is available at http://stroke.ahajournals.org DOI: 10.1161/STROKEAHA.112.657288
anosognosia index?? external rating?? self-rating
? external rating
To evaluate the validity of this new measure, the anosognosia index
was correlated with the Awareness Questionnaire6(n?62).
Lesions were mapped on a template brain with 5-mm axial slice
distance using MRIcroN. Due to the high correlation between
anosognosia and the severity of visuospatial neglect (see the online-
only Data Supplement), lesion analyses were confined to specific
patient subgroups. For patients showing visuospatial deficits, patient
pairs with identical external rating were identified. Subsequently,
each pair member was allocated to 1 of 2 groups based on his or her
self-rating. Patients without matching pair members (n?5) or with
identical scores (n?2) had to be discarded from these analyses. This
procedure yielded 2 groups of 11 patients each with identical
externally evaluated performance but different degrees of anosogno-
sia. Importantly, all other measures of visuospatial neglect did not
differ significantly between both groups (Table 2). Lesions were
compared with a voxelwise Liebermeister test7using a permutation
threshold of P?0.05.
Correlation analyses between the demographic and neuropsy-
chological variables revealed that anosognosia was more
severe with increasing age (see the online-only Data Supple-
ment). Moreover, the degree of anosognosia significantly
correlated with the performance in the 2 cancellation tasks,
ipsilesional line bisection errors and with the external rating
Lesion analysis was based on matched patient subgroups
with identical test performance but different degrees of
anosognosia (Table 2).
The Figure depicts the statistical test on the lesion locations
of the 2 subgroups. In the group with more severe anosog-
nosia, a significantly higher number of patients had lesions
affecting the right angular gyrus and the superior temporal
gyrus when compared with the group with lower anosognosia
(but comparable visuospatial impairment).
of the 2 Matched Patient Groups
Descriptive and Neuropsychological Data (Mean?SD)
LQ line cancellation
LQ star cancellation
Mean bisection error
Total score external rating
11 11. . .
27.4?1.6 Total score self-rating
LQ indicates laterality quotient.
*Paired t test (matched patient pairs).
Figure. Results of the lesion analyses. LpermutFWEindicates critical test score for significance after multiple comparison correction.
Vossel et alAnosognosia for Spatial Neglect After Stroke
To illustrate the lesion locations related to the presence of
visuospatial neglect irrespective of anosognosia in these
patients per se, the lesions of these patients were contrasted
with those of the remaining patients with normal perfor-
mance. This analysis revealed that regions within a dorsal
frontoparietal network and underlying white matter, together
with inferior parietal brain areas (Figure), were more fre-
quently damaged in patients with severely impaired visuospa-
Lesion volume was significantly higher in patients with
strong spatial neglect than in the remaining patients
(t?4.4; P?0.001), whereas no significant lesion volume
difference was observed between the matched higher and
lower anosognosia groups (t??1.3; P?0.226).
The total rating score of all 3 raters revealed high interrater
agreement (mean Pearson correlation coefficient r?0.973; all
3 coefficients ?0.96; P?0.001) and was highly correlated
with the laterality quotients and line bisection errors (see the
online-only Data Supplement). The anosognosia index sig-
nificantly correlated with the Awareness Questionnaire
By contrasting subjective with objective performance ratings
in visuospatial paper-and-pencil tests, the present study in-
vestigated anosognosia for spatial neglect and its neural
anatomy. Independent of the severity of the visuospatial
deficit per se, damage to the right inferior parietal and
superior temporal cortex was associated with higher anosog-
nosia, whereas anosognosia was not related to lesion size.
The new anosognosia test showed good reliability and
Anosognosia was strongly associated with different mea-
sures of visuospatial neglect. Moreover, as previously re-
ported,8anosognosia was more severe with higher age.
Hence, age might constitute an important factor for the
development of anosognosia. Interestingly, unawareness for
hemiplegia has also been critically related to visuospatial
deficits.9Note, however, that anosognosia for hemiplegia has
almost exclusively been studied in patients with visuospatial
impairment.10,11Although contrasting lesions of patients with
spatial neglect with and without anosognosia for hemiplegia
controls for the presence of a visuospatial impairment, the
severity of the visuospatial impairments may still differ
between groups. For this reason, a matching procedure was
used in the current study to control for the severity of the
visuospatial deficits. This analysis revealed that lesions af-
fecting the right angular and right superior temporal gyrus
were more prevalent in the group with more severe anosog-
nosia. This finding is in line with theoretical models of
impaired self-awareness for attentional deficits.12Moreover,
our results parallel findings from Berti et al10in the domain of
hemiplegia, because they also suggest function-specific neu-
ral correlates of self-awareness.
Patients with parietal lesions fail to integrate information
about performance outcome into future task execution plans,
that is, they do not benefit from error feedback in subsequent
trials of a task.13Along these lines, anosognosia for spatial
neglect may be caused by a deficient performance monitoring
in relation to discrepancies between intended and actual
achievements. Further support for this notion comes from
studies in the motor system, which show that the parietal
cortex is crucially involved in the conscious detection of
discrepancies between intended actions and perceived move-
We thank all our patients and are grateful to our colleagues from the
Research Centre Ju ¨lich and the University Hospital Cologne as well
as the Max-Planck Institute for Neurological Research Cologne for
providing the opportunity to acquire MRI scans.
Sources of Funding
S.V. is supported by the Deutsche Forschungsgemeinschaft (Vo
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