G.M.S. Nys

Cognitive function following stroke and vascular cognitive impairment.

Purpose of reviewThis review of the cognitive status following stroke and vascular cognitive impairment starts by questioning the concept of vascular dementia and related concepts. Our position is that in many cases these labels promote a superficial conceptualization of an inherently complex and heterogeneous phenomenon hampering a more detailed understanding. Recent findingsAfter stroke or disease of the cerebral vasculature, the cognitive and emotional outcome is dependent on a combination of three factors with the relative importance differing between causes. First, focal damage may lead to selective impairments that are dependent on the localization of the (grey matter) lesion. Second, diffuse neuronal dysfunction produces a more uniform profile of a decrease in mental speed, memory problems, and reduced executive functioning. Third, cognitive outcome is further modulated – notably in terms of severity – by patient variables such as age, sex, premorbid level of functioning, and comorbidity (e.g. hypertension). SummaryThe complex character of the cognitive repercussions of stroke can be better harnessed by employing modern neuropsychological assessment procedures. This allows both a detailed categorization of the patients for the selection and effectiveness of therapeutic intervention, as well as the construction of reliable prognostic models.

Cognitive differences between patients with left-sided and right-sided Parkinson's disease. A review.

At disease onset, patients with Parkinson’s disease (PD) typically report one side of the body to be more affected than the other. Previous studies have reported that this motor symptom asymmetry is associated with asymmetric dopaminergic degeneration in the brain. Research on the cognitive repercussions of this asymmetric degeneration has yielded inconsistent results. Here, we review studies that reported on the cognitive performance of patients with left-sided (LPD) or right-sided (RPD) motor symptom predominance. We present evidence that patients with RPD typically experience problems with language-related tasks and verbal memory, whereas patients with LPD more often perform worse on tasks of spatial attention, visuospatial orienting and memory and mental imagery. In general, no differences were found between both groups on tasks measuring attention and executive function. The association between motor asymmetry and cognitive performance indicates that PD does not lead to one typical cognitive profile. The effect of symptom laterality on the cognitive complaints should be considered in the assessment and treatment of each individual patient.

Prism adaptation improves voluntary but not automatic orienting in neglect

Prism adaptation has been shown to temporarily ameliorate the symptoms of unilateral neglect. The underlying mechanisms of change are not yet fully understood. In this study, we investigate the influence of this treatment on attentional orienting under conditions of exogenous (peripheral onset) and endogenous (central symbolic) cueing. In one patient with left visual extinction and recovered neglect, and another patient with left visual neglect, visuo-motor adaptation to a rightward prismatic shift of 10° improved leftward orienting of attention following an endogenous but not an exogenous cue; leftward re-orienting of attention was also improved in the endogenous task for the second patient. We suggest that prism adaptation may ameliorate neglect by improving compensatory processes of leftward voluntary orienting, rather than by a fundamental change in attentional bias.

Confabulation behavior and false memories in Korsakoff's syndrome: Role of source memory and executive functioning

Aims:  Confabulation behavior is common in patients with Korsakoffs syndrome. A distinction can be made between spontaneous and provoked confabulations, which may have different underlying cognitive mechanisms. Provoked confabulations may be related to intrusions on memory tests, whereas spontaneous confabulations may be due to executive dysfunction or a source memory deficit.

Repetitive long-term prism adaptation permanently improves the detection of contralesional visual stimuli in a patient with chronic neglect.

The aim of the current study was to investigate long-term effects in spatial awareness after daily exposure to prism adaptation during three months in a patient with hemispatial neglect. Results showed improvement in the detection of stimuli in the contralesional visual field, as measured with perimetry, in the contralesional visual field up to 24 months after ending prism adaptation. These perimetrical results suggest that compensatory eye movements are an unlikely candidate for an underlying mechanism.

Hyperglycemia and cognitive outcome after ischemic stroke

BACKGROUND Post-stroke hyperglycemia (HG) is associated with poor physical recovery, in particular in patients with cortical stroke. We tested whether HG is also associated with cognitive impairment after ischemic stroke. METHODS We recruited patients from a prospective consecutive cohort with a first-ever supratentorial infarct. Neuropsychological examination included abstract reasoning, verbal memory, visual memory, visual perception and construction, language, and executive functioning. We related HG (glucose >7.0 mmol/L) to cognition and functional outcome (modified Barthel Index) at baseline and after 6-10 months, and to neurological deficit (National Institutes of Health Stroke Scale) and infarct size at baseline. In additional analyses cortical and subcortical infarcts were considered separately. RESULTS Of 113 patients, 43 had HG (38%) and 55 had cortical infarcts (49%). Follow-up was obtained from 76 patients (68%). In the acute phase, in patients with cortical infarcts HG was associated with impaired executive function (B=-0.65; 95% confidence limits (CL): -1.3-0.00; p<0.05), larger lesion size (p<0.01), and more severe neurological deficits (p<0.01). These associations were not observed in patients with subcortical infarcts and the association between HG and cognitive functioning at follow-up was not significant in either group. CONCLUSIONS In first-ever ischemic stroke, HG was not associated with impaired cognition after 6-10 months. In the acute phase of stroke HG was associated with impaired executive function, but only in patients with cortical infarcts.

Prism adaptation moves neglect-related perseveration to contralesional space.

BackgroundHemi-neglect is a disorder characterized by a disregard of contralesional stimuli. Some neglect patients also show an “exaggerated attention” for the ipsilesional field, reflected in perseverative responses, such as repetitive fixations in the ipsilesional field, ipsilesional revisitings on standard cancellation, or exaggerations in drawings on the ipsilesional side. Objective and MethodIt is still unclear whether neglect and perseveration are due to a single underlying mechanism. In the present study, we will examine the effect of 4-day-in-a-row prism adaptation on neglect and perseveration severity in a patient with severe perseverations. Additionally, we will examine whether the position of omissions and perseverations on the Star Cancellation will change during the intervention. ResultsOur patient showed a decrease in neglect severity and an increase in perseveration severity, suggesting that perseveration and neglect are dissociated phenomena. Interestingly, 4-day-in-a-row prism adaptation gradually moved the predominant position of perseverative responses from right to left as neglect decreased with treatment. ConclusionsPerseverative responses do not necessarily occur in the ipsilesional sector of space as is generally assumed. Instead, the position of the revisits may be determined by the severity of the neglect, and may shift when the focus of attention moves more contralesionally with recovery.

The Brixton Spatial Anticipation Test as a test for executive function: validity in patient groups and norms for older adults.

Impairments in executive functioning frequently occur after acquired brain damage, in psychiatric disorders, and in relation to aging. The Brixton Spatial Anticipation Test is a relatively new measure for assessing the ability to detect and follow a rule, an important aspect of executive functioning. To date, normative data on this task are limited, particularly concerning the elderly. This study presents age- and education-adjusted regression-based norms obtained in a group of healthy older participants (n = 283; mean age 67.4 +/- 8.5 years). The applicability and validity of these norms were further examined in different groups of patients with stroke (n = 106), diabetes mellitus (n = 376), MCI/early dementia (n = 70), psychiatric disorders (n = 63), and Korsakoffs syndrome (n = 41). The results showed that patients with Korsakoffs syndrome, stroke, and psychiatric disorders performed significantly worse than healthy controls. Test-retest correlation (n = 83), learning effects, and correlations with other neuropsychological tests were also explored. Based on the present study, the Brixton test appears a useful addition to existing measures of executive functioning. Moreover, the test can be reliably applied in different groups of clinical patients.

Delirium in acute stroke: A predictor of subsequent cognitive impairment?: A two-year follow-up study

OBJECTIVE Delirium is an independent risk factor for cognitive impairment and development of dementia in medical patients. It has never been thoroughly studied whether this association is also present in the stroke population. Our aim was to evaluate the effects of delirium in the acute phase after stroke on cognitive functioning two years later. METHODS Two years after stroke, 50 patients (22 with and 28 without delirium in the acute phase) were assessed on two screening instruments for dementia and a neuropsychological test battery. RESULTS Delirium was an independent predictor for development of dementia as assessed by the Clinical Dementia Rating Scale (odds ratio (OR) 4.7; 95% confidence interval (CI) 1.08 to 20.42) and by the Rotterdam-CAMCOG (OR 7.2, 95% CI 1.88 to 27.89). Cognitive domains most affected in patients with previous delirium were memory, language, visual construction and executive functioning. CONCLUSIONS Delirium in the acute phase after stroke is an independent predictor for severe cognitive impairment two years after stroke. These findings emphasize the importance of both rapid detection and treatment of delirium after stroke. Furthermore, periodic monitoring and evaluation of cognitive functioning in these vulnerable patients in the years after stroke is strongly recommended.

Horizontal and vertical attentional orienting in Parkinson’s disease

Patients with Parkinsons disease (PD) typically suffer from an asymmetric degeneration of dopaminergic cells in the substantia nigra, resulting in right-sided (RPD) or left-sided (LPD) predominance of motor symptomatology. As the dopaminergic system is also involved in attention, we examined horizontal and vertical orienting of attention in LPD (N=10), RPD (N=9) and controls (N=10). Four LPD patients demonstrated left neglect and three LPD patients demonstrated neglect for the upper visual field. LPD patients demonstrated a slower performance in detecting targets in the left hemifield and did not demonstrate a validity effect, unlike RPD patients and controls. RPD patients performed similar to controls, with the exception of one patient showing left and another showing right neglect, and two RPD patients demonstrated lower neglect. In sum, horizontal and vertical orienting of attention can be affected in Parkinsons disease - particularly in LPD - from very subtle slowing to clinically detectable horizontal and/or vertical neglect.