Visual extinction in relation to visuospatial neglect after right-hemispheric stroke: quantitative assessment and statistical lesion-symptom mapping.
BACKGROUND
Visual neglect and extinction are two common neurological syndromes in patients with right-hemispheric brain damage. Whether and how these two syndromes are associated or share common neural substrates is still a matter of debate.


METHODS
To address these issues, the authors investigated 56 patients with right-hemispheric stroke with a novel diagnostic test to detect extinction and neglect. In this computerised task, subjects had to respond to target stimuli in uni- and bilateral stimulation conditions with detection probabilities being assessed. A cluster-analytical approach identified 18 patients with neglect and 13 patients with extinction. Statistical lesion-symptom mapping analyses with measures for extinction and neglect were performed.


RESULTS
Extinction and neglect co-occurred in a subset of patients but were also observed independently from each other, thereby constituting a double dissociation. Lesions within the right inferior parietal cortex were significantly associated with the severity of visual extinction. Visuospatial neglect was related to damage of fronto-parietal brain regions, with parieto-occipital areas affecting line bisection and dorsal fronto-parietal areas affecting cancellation task performance, respectively.


CONCLUSIONS
Quantifying lesion-induced symptoms with this novel paradigm shows that extinction and neglect are dissociable syndromes in patients with right-hemispheric stroke. Furthermore, extinction and neglect can be related to differential neural substrates, with extinction being related to focal brain damage within the right inferior parietal cortex.
Cognitive Neurology Section, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich, Leo-Brandt-Str 5, 52425 Jülich, Germany. s.vossel@fz-juelich.de
S
S
Vossel
P
P
Eschenbeck
P H
PH
Weiss
R
R
Weidner
J
J
Saliger
H
H
Karbe
G R
GR
Fink
D016000:Cluster Analysis; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000592:standards* / Q000706:statistics & numerical data; D010296:Parietal Lobe / Q000503:physiopathology; D010364:Pattern Recognition, Visual; D010468:Perceptual Disorders / Q000175:diagnosis* / Q000209:etiology; D012720:Severity of Illness Index; D013028:Space Perception; D020521:Stroke / Q000150:complications*