The Neuropsychology of Acute Stroke : Characterisation and Prognostic Implications

Abstract

In this thesis, a longitudinal study was performed in a large cohort of patients with a first symptomatic stroke who had no neurological, psychiatric, and/or cognitive history prior to the stroke. The patient cohort was examined in a very early phase (mean interval eight days post-stroke) with a neuropsychological evaluation covering 7 major cognitive domains. The examination was feasible in 168 of 190 included patients (88%). At hospital admission, demographic data, lesion characteristics, clinical factors at admission, and pre-existent vascular risk factors were also recorded. The follow-up examination was administered after six to ten months, in which we examined cognitive outcome, functional outcome, emotional outcome, and quality of life. A demographically matched healthy control group (N=75) was also examined with the same time interval between baseline and follow-up assessment to obtain a reference sample for the neuropsychological examination.

The first part of this thesis (Chapters 2-5) reports a series of studies on the phenomenology, course, and prognostic implications of cognitive disorders in the early phase of stroke. The most important finding in this section is that cognitive disorders at baseline are powerful predictors of long-term dependence in daily life, long-term cognitive impairment, and a reduced quality of life, beyond that of well-known medical predictors. Particularly disorders in executive functioning and visual perception/ construction predict poor outcome in the long term. We recommend neuropsychological assessment as a standard evaluation on the stroke unit, and plead for a detailed characterisation of the cognitive disorder(s) rather than classifying all impairment under one general header.

The second part of this thesis (Chapters 6-7) studies the prevalence and clinical determinants of depressive symptoms (DS) after stroke. No evidence was obtained for a direct relation between DS and lesion location, neither in the acute phase nor in the long term. Conversely, a close association between long-term DS and (i) acute cognitive impairment and (ii) vascular risk factors could be demonstrated. It is concluded that DS are a psychological reaction to the devastating consequences of stroke. In addition, vascular risk factors may play a role in exacerbating DS in the long term.

In the third part (Chapter 8), we examined whether thrombolytic treatment has a favourable effect on cognitive and functional outcome after six months post-stroke. Multivariate logistic regression adjusted for stroke severity, age, education, and sex based on 117 first-ever stroke patients demonstrated that thrombolytic treatment is associated with a favourable basic and instrumental ADL outcome, but not with a beneficial cognitive outcome after six months.

Apart from the clinical merits, the neuropsychological examination in the first weeks allowed for the early identification of two patients with uncommon cognitive disorders (Chapter 9-10). In Chapter 9, the neuropsychological correlates of spontaneous confabulation are studied. This case study suggests that mental flexibility rather than executive functioning in general is related to spontaneous confabulation in amnesic patients. In chapter 10, fMRI was used to examine the neuro-anatomical correlates of visual hallucinations in a hemianopic patient. Bilateral activation was observed in the calcarine fissure and medially in the left and right occipital cortex adjacent to the infarcted areas, in line with fMRI findings from hallucinating patients with Charles Bonnet and Lewy body dementia.

In the final part (Chapter 11), a general discussion is presented comprising an integration of the main findings of this thesis, in addition to a discussion on our methodology and some future recommendations.