Neuropsychological and neuroanatomical correlates of perseverative responses in subacute stroke

Patients with left-sided neglect frequently show repetitive behaviour on the ipsilesional side, such as re-markings on cancellation tasks or extensive elaboration on drawings. It is unclear whether these perseverative responses occur as a symptom of hemi-neglect or inattention in general, and/or whether they are related to anatomical brain correlates such as lesion location, lesion side or volume. In a first study, we examined the prevalence and neuropsychological correlates of perseverative responses in 206 subacute stroke patients and 63 healthy controls. Perseverative responses were considered present when there was at least one re-marking on the Star Cancellation, and both the degree and spatial distribution of re-markings were examined. A distinction was made between hemi-neglect and non-lateralized inattention. Spatial and verbal working memory were assessed with the Corsi Block Span and the Digit Span. Verbal and non-verbal executive function was assessed with the Visual Elevator and Letter Fluency. Stroke patients without inattention demonstrated re-markings that were related to executive performance, and the degree of perseveration was equally distributed across the sheet. Hemi-neglect patients but not patients with generalized inattention demonstrated more re-markings than controls, suggesting that a lateralized spatial attention bias triggers the perseverative responses. Patients with left and right hemi-neglect showed the same prevalence of perseveration, but the distribution of re-markings was more lateralized towards the ipsilesional side in patients with right-hemispheric stroke. The degree of perseveration in patients with hemi-neglect was related to the severity of the neglect. The goal of the second study on a subset of patients (n = 127) was to determine the neuroanatomical correlates of perseverative responses in the early phase of stroke. Lesion anatomy was administered by indicating involvement of frontal, parietal, temporal, occipital lobe, caudate nucleus, lenticular nucleus and/or thalamus. Lesion volume was calculated using a manual tracing technique. Lesion analyses indicated that perseverative behaviour is strongly associated with lesions involving the caudate nucleus or the lenticular nucleus, independent of lesion volume. The caudate nucleus was an important correlate of perseveration independent of the presence of hemi-neglect. No association was found between lesion side and perseverative responses, in contrast to previous studies. In conclusion, a stroke involving the basal ganglia and the presence of (left- or right-sided) hemi-neglect are two important associates of perseverative responses in the subacute phase of stroke.