NINDS AIREN neuroimaging criteria do not distinguish stroke patients with and without dementia

OBJECTIVE

To determine the utility of the neuroimaging component within the National Institute of Neurological Disorders and Stroke (NINDS) Association Internationale pour la Recherche et l'Enseignement en Neurosciences (AIREN) criteria for vascular dementia for distinguishing between patients with and without dementia in the context of cerebrovascular disease.

METHOD

One hundred twenty-five poststroke patients age > or =75 (27 with and 98 without poststroke dementia) from representative hospital-based stroke registers in the North East of England were evaluated using a 1.5 T MR scanner. The proportion of patients with and without poststroke dementia meeting the imaging component of the NINDS AIREN criteria was determined, and hippocampal atrophy (measured using the Schelten scale) was compared between the two groups.

RESULTS

There were no significant differences between the patients with and without poststroke dementia on any criteria of the imaging parameters within the NINDS AIREN criteria. In addition, there were no significant differences in the number or size of cortical or subcortical infarcts between the two groups, with 13 patients without dementia having cortical infarcts >50 mm. Patients with dementia had greater hippocampal atrophy (right: Mann-Whitney U test, Z = 2.5, p = 0.01; left: Mann-Whitney U test, Z = 2.5, p = 0.01).

CONCLUSION

The neuroimaging component of the NINDS AIREN criteria does not distinguish between older patients with and without poststroke dementia.

Only spontaneous counterfactual thinking is impaired in patients with prefrontal cortex lesions

Counterfactual thoughts (CFT) are mental simulations of what might have been if another behavior had been executed. They are pervasive in everyday life, help people learn from experience, modulate their emotional state, and contribute to decision-making and social functioning. To test the hypothesis that the prefrontal cortex (PFC) is involved in the generation, content, and use of CFT, we studied 18 patients with strictly prefrontal cortex lesions. Our results indicated that the PFC is crucial only for self-generated counterfactual reflections. We did not detect CFT generation differences based on lesion location within the PFC. CFT performance correlated positively with measures of attention, creativity, verbal skills, conscientiousness, and self-esteem and negatively with depression and dysexecutive symptoms. An impairment in counterfactual thinking may contribute to the lack of regret and insight often observed in patients with frontal lobe lesions.

Progressive morphometric and cognitive changes in vascular dementia

Evidence for progressive cognitive decline in vascular dementia (VaD) is mixed, with some studies showing little or no decline over time. One possible explanation for these inconsistent findings is the heterogeneity of pathology encompassed by the VaD diagnosis. It is possible that subtypes of VaD (i.e. those resulting from different lesion distributions) show different patterns of cognitive decline. In the present study, a heterogeneous VaD group demonstrated cognitive decline from baseline to 12-month follow-up. Although this decline was coincident to morphometric changes (i.e. increased subcortical hyperintensities (SH), decreased whole brain volume (WBV)), no relationship emerged between cognitive decline and morphometric changes. Preliminary examination of VaD subtypes revealed patients with subcortical infarct or SH-only exhibited greater decline than VaD patients with cortical lesions. Further research is needed to determine whether this observed decline is attributable to differential lesion distribution or statistical artifact.

Mild depression in young adults with cerebral infarction at long-term follow-up: A population-based study

We sought to evaluate the prevalence of and risk factors for post-stroke depression (PSD) at long-term follow-up in young adults aged 15-49 years with first-ever cerebral infarction in a population-based study. Scores on Montgomery-Asberg Depression Rating Scale (MADRS) were obtained at follow-up (mean time 6.0 years after the stroke) and analysed in subgroups. MADRS scores were obtained in 196 of 209 surviving patients. PSD (MADRS>or=7) was detected in 56 patients (28.6%). None had severe PSD. Alcoholism (P=0.006), depressive symptoms any time before the index stroke (P=0.016), and severe neurological deficits on admission for the index stroke (P=0.043) were independently associated with PSD. PSD seems milder in young ischaemic stroke patients compared with older patients. Alcoholism, depression any time before the index stroke, and severity of neurological deficits on admission for the stroke increased the risk of developing PSD in the long run.

Cortical Control of Visually Guided Reaching: Evidence from Patients with Optic Ataxia

The dorsal stream of visual information processing connecting V1 to the parietal cortex is thought to provide a fast control of visually guided reaching. Important for this assumption was the observation that in both the monkey and the human, parietal lesions may provoke disturbance of visually goal-directed hand movements. In the human, severe misreaching termed 'optic ataxia' has been ascribed to lesions of the superior parietal lobule (SPL) and/or the intraparietal sulcus. Using new tools for lesion analysis, here we re-evaluated this view investigating the typical lesion location in a large group of unilateral stroke patients with optic ataxia, collected over a time period of 15 years. We found no evidence for the assumption that disruption of visually guided reaching in humans is associated with a lesion typically centering on the SPL on the convexity. In both left and right hemispheres, we found optic ataxia associated with a lesion overlap that affected the lateral cortical convexity at the occipito-parietal junction, i.e. the junction between the inferior parietal lobule (IPL) and superior occipital cortex and--in the left hemisphere even more posteriorly--also the junction between occipital cortex and the SPL. Via the underlying parietal white matter, the lesion overlap extended in both hemispheres to the medial cortical aspect, where it affected the precuneus close to the occipito-parietal junction. These lateral and medial structures seem to be integral to the fast control of visually guided reaching in humans.

Attentional functions of parietal and frontal cortex

A model of normal attentional function, based on the concept of competitive parallel processing, is used to compare attentional deficits following parietal and frontal lobe lesions. Measurements are obtained for visual processing speed, capacity of visual short-term memory (VSTM), spatial bias (bias to left or right hemifield) and top-down control (selective attention based on task relevance). The results show important differences, but also surprising similarities, in parietal and frontal lobe patients. For processing speed and VSTM, deficits are selectively associated with parietal lesions, in particular lesions of the temporoparietal junction. We discuss explanations based on either grey matter or white matter lesions. In striking contrast, measures of attentional weighting (spatial bias and top-down control) are predicted by simple lesion volume. We suggest that attentional weights reflect competition between broadly distributed object representations. Parietal and frontal mechanisms work together, both in weighting by location and weighting by task context.

Contrasting effects of phonological priming in aphasic word production

Two fluent aphasics, IG and GL, performed a phonological priming task in which they repeated an auditory prime then named a target picture. The two patients both had selective deficits in word production: they were at or near ceiling on lexical comprehension tasks, but were significantly impaired in picture naming. IG's naming errors included both semantic and phonemic paraphasias, as well as failures to respond, whereas GL's errors were mainly phonemic and formal paraphasias. The two patients responded very differently to phonological priming: IG's naming was facilitated (both accuracy and speed) only by begin-related primes (e.g. ferry-feather), whereas GL benefited significantly only from end-related primes (e.g. brother-feather), showing no more than a facilitatory trend with begin-related primes. We interpret these results within a two-stage model of word production, in which begin-related and end-related primes are said to operate at different stages. We then discuss implications for models of normal and aphasic word production in general and particularly with respect to sequential aspects of the phonological encoding process.

Hypersexuality and dysexecutive syndrome after a thalamic infarct

Hypersexuality can result from insults to several neuroanatomical structures that regulate sexual behavior. A case is presented of an adult male with a thalamic infarct resulting in a paramedian thalamic syndrome, consisting of hypersomnolence, confabulatory anterograde amnesia (including reduplicative paramnesia), vertical gaze deficits, and hypophonic speech. A dysexecutive syndrome also manifested, consisting of social disinhibition, apathy, witzelsucht, motor inhibition deficits, and environmental dependence. Hypersexuality uncharacteristic of his premorbid behavior was evident in instances of exhibitionism, public masturbation, and verbal sexual obscenities. In contrast to the few previous reports of hypersexuality following thalamic infarct, this case neither involved mania nor hemichorea. The relevance of the mediodorsal thalamic nucleus in limbic and prefrontal circuits is discussed.

[Clinical effects of paxil in poststroke rehabilitation]

The efficacy of antidepressant paxil was studied in 30 patients, aged 30-70 years, who had survived stroke in the interior carotid arteries area, with pronounced affective disorders (illness duration over 3 months). Paxil was prescribed in an initial dosage of 20 mg daily during 12 weeks. A significant clinical antidepressive and anxiolytic effect of paxil was observed and confirmed by the data of cluster analysis. An inclusion of paxil in a complex of rehabilitative measures allowed to improve patients quality of life.

Prevalence and pathogenic role of cerebrovascular lesions in Alzheimer disease

Cerebrovascular lesions in Alzheimer disease (AD) being significantly more frequent than in nondemented elderly subjects suggest overlaps and synergistic effects between both pathologies. Examination of a consecutive series of autopsy-proven AD cases and age-matched controls revealed a higher frequency of vascular lesions and of cerebral amyloid angiopathy (CAA) in AD (57.34% vs. 33.2% and 94.1% vs. 33.3%, respectively). These and previous data on vascular pathology in Parkinson disease emphasize its importance in these disorders. A study comparing the frequency and extent of general CAA and capillary CAA (CapCAA) in the postmortem frontal cortex of cases with high and low Braak stages showed no correlation between general CAA and dementia, only a low one with other vascular lesions except for cerebral hemorrhages. However, it was higher in AD than in controls with vascular pathology. The severity of CapCAA not correlating with general CAA showed high correlation with AD pathology, suggesting different pathogenesis of both types of CAA. Its elucidation may have implications for new therapeutic strategies. Considering the variability of vascular pathology in both AD and aged brains, the mechanisms behind their interactions are largely unknown, and further studies are needed to clarify their impact on cognitive impairment.

Empowerment, quality of life and participation in neurological rehabilitation: Empirical study with stroke patients and their relatives

The active role (participation) that patients with chronic conditions are able to achieve has increasingly been recognised as a measure for the effectiveness of prevention- and rehabilitation strategies. An empowerment scale is an especially effective instrument for measuring social participation, and was applied to stroke patients in neurological rehabilitation for the first time. 26 stroke survivors and 26 informal carers, who participated in self-help groups in Lower Austria, were surveyed. The mean age was 63.9 (+/- 10.4) (stroke survivors) and 61.9 (+/- 9.6) years (informal carers). The mean duration of disease was 7.3 (+/- 3.2) years and the mean length of self-help group participation approximately 4 years. Every other stroke survivor and every fifth informal carer had to give up their professional life because of the stroke. Financial burden, reduction of vacations and social activities was found for both groups. Informal carers more frequently reported an increased fear of a relapse and generally of the future. One third of the stroke survivors had insomnia, depression, and nervousness. Reduced mobility, memory impairment, and increased sensitivity to temperature-changes were seen as the largest burdens. In spite of the large overlap in many domains of empowerment- and quality-of-life measures, empowerment measures also seem to reflect aspects of social participation. Therefore, measures of empowerment should be included in long-term outcome measurements following stroke.

The role of executive functioning in spontaneous confabulation

OBJECTIVE

To follow the recovery course of a patient who exhibited an amnesic-confabulatory syndrome in conjunction with severe executive dysfunction in the first week following bithalamic infarction.

BACKGROUND

Previous studies have shown that spontaneous confabulation originates from the combination of amnesia and executive dysfunction and that the degree of confabulation is determined by the degree of executive dysfunction. However, a few studies have also reported a dissociation between spontaneous confabulation and executive dysfunction. Therefore, the role of executive functioning in spontaneous confabulation is presently unclear.

METHOD

Clinical examinations, magnetic resonance imaging (MRI), and cognitive and behavioral assessments with a focus on executive functions were conducted within the first week poststroke and after 6 months.

RESULTS

MRI showed a bithalamic infarction involving the territory of the paramedian arteries predominantly affecting the dorsomedial and intralaminar nuclei of the thalami. Disappearance of spontaneous confabulation paralleled a specific recovery in mental flexibility, whereas all other executive components and long-term memory remained severely impaired at 6 months poststroke.

CONCLUSIONS

Our case study provides additional evidence that mental flexibility, but not executive functioning in general, is a prerequisite for spontaneous confabulation. Direct or indirect functional deactivation of dorsolateral prefrontal cortex may be necessary for the development of spontaneous confabulation.

Relationship of Local Infarctions to Cognitive and Psychosocial Impairments after Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE:

Previous studies suggest that cognitive and psychosocial impairments after subarachnoid hemorrhage (SAH) result from diffuse brain damage caused by the initial bleeding rather than from focal lesions. We describe the relationship of local infarctions to these impairments and explore how well test and questionnaire results explain psychosocial outcome.

METHODS:

A total of 170 patients, selected from a consecutive series of patients with aneurysmal SAH, underwent neurological and neuroradiological examinations, and 138 of them were assessed with neuropsychological tests and questionnaires 1 year after SAH.

RESULTS:

Patients with left and bilateral infarctions performed worse on verbal memory tests than the other patients, and patients with left infarctions had more impaired working capacity than those with no infarction. The indices of the severity of SAH were related to reductions in both working capacity and social activity but less clearly to poor test performances. Whereas the modified Rankin scale was the most important correlate of working capacity, performance on cognitive tests was associated with return to work, and questionnaire ratings of mental impairments correlated with reduced working capacity and decreased social activity.

CONCLUSION:

Left-hemisphere infarctions cause deficits in verbal memory and working capacity. The severity of SAH is associated with impairments in working capacity and social activity rather than with specific cognitive deficits. Patients' and partners' opinions on patients' mental impairments could provide complementary information to clinical grades and cognitive tests in the evaluation of outcome after SAH.

Poststroke depression: psychopharmacological considerations

PSD is a common psychiatric complication of stroke. It is often underrecognized and untreated. Numerous studies show that untreated PSD impedes the rehabilitation and recovery process, jeopardizes quality of life, and increases mortality. Successful management of the PSD requires early recognition and initiation of appropriate treatment to facilitate an optimal level of functioning. As active members of the interdisciplinary treatment team, psychiatric consultative-liaison nurses play a pivotal role in facilitating positive treatment outcomes during both the acute and rehabilitation phases in the management of PSD.

The role of brain infarcts and hippocampal atrophy in subcortical ischaemic vascular dementia

We investigated if, in patients with vascular lesions, the variable that best discriminated demented from non-demented patients was the severity of the vascular pathology or the degree of hippocampal atrophy. A total of 39 patients multiple subcortical infarcts, who could be considered as possible vascular dementia with small vessel pathology, with underwent a neuropsychological study and brain magnetic resonance imaging (MRI) DSM IV criteria supported by neuropsychological data were used to distinguish demented from non-demented patients. The MRI study took into account the degree of hippocampal atrophy (hippocampal height and interuncal distance) and the severity of vascular pathology (number of brain infarcts). The distribution of lesions and a factor analysis showed that hippocampal atrophy is a better predictor of dementia than the number of brain infarcts. Multiple subcortical infarcts alone are probably not able to cause clinical dementia but the presence of vascular lesions increases the expression of concomitant Alzheimer's disease.

The neuropsychological profile of vascular cognitive impairment?no dementia: comparisons to patients at risk for cerebrovascular disease and vascular dementia

Hachinski and co-workers have used the term vascular cognitive impairment-no dementia (VaCIND) to represent the earliest stages of cognitive decline associated with vascular changes [Neurology 57 (4) (2001) 714]. However, the neuropsychological profile of vascular CIND remains unclear. Twenty-five healthy elders, 29 individuals at risk for cerebrovascular disease (R-CVD), 18 individuals with VaCIND, and 26 individuals with vascular dementia (VaD) were examined to determine whether patterns of neuropsychological assessment performance can assist in the differentiation of patients at varying levels of risk and severity for cerebrovascular disease and VaD. The R-CVD group performed within normal expectations on most cognitive measures as compared to the elderly control sample and published clinical norms. Relative to elderly controls, the VaCIND group demonstrated significant difficulties on measures of cognitive flexibility, verbal retrieval, and verbal recognition memory, but not on measures of confrontational naming or verbal fluency. The VaD group was impaired on all cognitive measures assessed. The current findings suggest that poor cognitive flexibility and verbal retrieval in the context of preserved function in other domains may characterize the prodromal stage of VaD.

Impaired Novelty Processing in Apathy After Subcortical Stroke

Background and Purpose— Apathy is associated with decreased novelty-seeking behaviors and is a prevailing behavioral symptom after stroke affecting cortical and subcortical regions. We studied the relationship between apathetic state after subcortical stroke and neural orienting response to novel events using an event-related evoked potential (ERP) technique.

Methods— Twenty-nine patients with subcortical ischemic stroke were grouped according to whether they showed apathy or not. We analyzed apathy state scaled by the modified Starkstein apathy score and auditory P3 ERP components evoked by task-relevant target stimuli (target P3) and task-irrelevant novel stimuli (novelty P3).

Results— The apathetic group showed a significantly lower score of verbal fluency test and global cognitive function test compared with the nonapathetic group. The novelty P3 latency was significantly prolonged, and its amplitude was reduced over the frontal site in the apathy group. The apathy scale was correlated with the novelty P3 latency and amplitude at the frontal site. The target P3 measures were related to global cognitive function.

Conclusions— The present study suggests that apathy after subcortical stroke is associated with impaired neural processing of novel events within the frontal–subcortical system and that the novelty P3 is a useful physiological measure for assessing apathy after stroke.

Bimanual recoupling by visual cueing in callosal disconnection

The cerebral control of bimanual movements is not completely understood. We investigated a 59-year-old, right-handed man who presented with an acute bimanual coordination deficit. Magnetic resonance imaging showed a lesion involving the entire corpus callosum, which was found on stereotactic biopsy to be an ischemic infarct. Paired-pulse transcranial magnetic stimulation indicated that the patient had a lack of interhemispheric inhibition, while intracortical inhibition in motor cortex of either side was normal. Functional magnetic resonance imaging showed activation of the left SMA, the bilateral motor cortex and anterior cerebellum during spontaneous bimanual thumb-index oppositions, which were uncoupled as evident from simultaneous electromyographic recordings. In contrast, when the bimanual thumb-index oppositions were cued by a visual stimulus, the movements of both hands were tightly correlated. This synchronized activity was accompanied by additional activations bilateral in lateral occipital cortex, dorsal premotor cortex and cerebellum. The data suggest that the visually cued movements of both hands were recoupled by action of a bihemispheric motor network.

Influence of motor disorders on the visual perception of human movements in a case of peripheral dysgraphia

We report the case of a 71 year-old female patient (DC) with a left parietal lesion resulting in a peripheral dysgraphia essentially characterized by difficulties in letter sequences writing. The aim of our experiments was to analyze the influence of motor difficulties on the visual perception of both writing and reaching movements. Results showed a strong link between motor and perceptual performance. For reaching movements, performances in both production and perception tasks conform to the motor principles identified in healthy subjects (Fitts' law and motor anticipation). By contrast, for handwriting movements, DC's productions do not follow the motor principles usually observed in normal subjects (isochrony principle, motor anticipation) and in perception the same results were observed. The motor references used by DC in the visual perception of writing movement were not the laws of movement but rather her own way of writing. Taken together these data strongly suggest that motor competences is involved in the visual perception of human movements. They are discussed in the general framework of the simulation theory.

Preserved knowledge of maps of countries: implications for the organization of semantic memory

We describe two patients with selectively preserved knowledge of the category of countries. Following a series of cerebral infarcts, patient DB presented with severe perceptual impairment, including dense apperceptive agnosia,prosopagnosia, and topographical agnosia. Despite these deficits, he could effortlessly name countries from their outline maps. Patient WH, who suffered from semantic dementia, had severe naming and comprehension difficulties, with extremely sparse residual semantic knowledge. Remarkably, the category of countries was preserved. First, we argue that, for both patients, this category preservation occurs at a semantic level. Second, we discuss our findings in the context of three current models of category-specific effects (perceptual, ontogenetic, and evolutionary models). We argue that the perceptual model (Humphreys and colleagues) cannot easily accommodate our findings. By contrast, the ontogenetic (Warrington and colleagues) and evolutionary models (Caramazza and colleagues) can explain our findings. However, some modifications to both models are required. The ontogenetic model needs to envisage a spatial channel for the development of map knowledge, which is anatomically separate from channels of other categories of knowledge. The evolutionary model needs to envisage the possibility that some categories of knowledge, such as countries, may not be prewired, but learned during ontogenetic development.

Differential Effect of Right and Left Basal Ganglionic Infarctions on Procedural Learning

OBJECTIVE

To assess the effect of ischemic infarctions affecting the basal ganglia (BG) region on a series of procedural learning tasks.

BACKGROUND

The basal ganglia hypothesis of procedural learning is a matter of debate. As most of the relevant research so far is based on examination of patients suffering from Parkinson disease, this inconsistency might reflect either lesion heterogeneity existing in this pathologic group or the heterogeneity of the procedural learning tasks.

METHOD

Twelve patients with lesions confined to the right (BGr), 10 to the left (BGI) BG region, and 15 matched controls participated in the study. Three procedural learning tasks were used: Tower of Hanoi Puzzle, Mirror Reading, and Porteus Mazes. Declarative memory and general intelligence were also tested.

RESULTS

Verbal declarative memory was impaired in the BG1 group. For each procedural learning task, baseline performance and learning rate were analyzed. Tower of Hanoi Puzzle: Baseline performance of the BG1 group was impaired compared with the other groups. The BGr group was the only group that did not improve over learning trials. MR: Baseline performance of the BGr group was impaired compared with the other groups. The groups' learning rate did not differ significantly. Porteus Mazes: Baseline performance of both patient groups was impaired compared with that of the control group. Learning rate over repetitive trials of the same maze was impaired in the BGr group. However, the transfer of procedural learning to a newly exposed maze was impaired in the BG1 group.

CONCLUSIONS

First, right and left basal ganglia play different roles in different procedural learning tasks. Second, procedural learning is not a unitary capacity subserved by any single neural mechanism.

Frontal deficits in alcoholism: An ERP study

Alcoholism is a major health problem afflicting people all over the world. Understanding the neural substrates of this addictive disorder may provide the basis for effective interventions. So-called "executive processes" play a role in cognitive functions like attention and working memory, and appear to be disrupted in alcoholism (Noel et al., 2001). Event related potentials (ERPs) provide an excellent, minimally invasive technique for exploring these neural deficits. The current study used the P300 in number sequencing task (modified version of the Petries & Milner, 1982) requiring working memory to compare a group of patients with alcoholism and frontal lobe lesions to patients with subcortical lesions and normal controls to assess the relationship of alcoholism to frontal lobe damage. The ERP paradigm was a Number Sequencing task. Electrophysiological results indicate that the frontal lesion group had significant P300 amplitude reduction and a similar trend for alcohol dependent group but not the subcortical group compared to the normal controls.

[Dementia secondary to thalamic infarct: a case report]

INTRODUCTION

The term dementia refers to the deterioration of the intellectual or cognitive functions, with little or no alteration of consciousness, which is capable of interfering with the activities of daily living and the ability to cope by oneself. One infrequent cause of dementia is its being secondary to a thalamic lesion and is normally due to the involvement of both thalami.

CASE REPORT

We report a case of sudden onset dementia caused by lesions affecting only the left thalamus. A 64 year old right handed female patient with chronic arterial hypertension for which she received regular treatment. The patient visited because of difficulty in speaking without any alterations to consciousness, and amnesia of recent anterograde and retrograde events. A CAT scan of the brain revealed a superlacuna in the left thalamus. From then on, the patient presented memory disorders, the most typical being loss of retention memory.

CONCLUSIONS

Thalamus injuries that are accompanied by dementia are commonly bilateral and are preferably located in the anterior and medial nuclei. There have been cases of memory disorders secondary to unilateral infarcts of the thalamus and these are related to a thalamocortical deafferentiation. Our case is one of sudden onset thalamic dementia secondary to an infarct affecting only the left thalamus.

Electrobehavioral characteristics of epileptic rats following photothrombotic brain infarction

The goal of this study was to characterize the electroencephalographic (EEG) and behavioral properties of young adult rats during extended video-EEG monitoring following photothrombotic brain infarction. Two-month-old male Sprague-Dawley rats underwent photothrombotic brain infarction of the left sensorimotor cortex with the photosensitive dye rose bengal (n=10) or were used as controls (n=9). Qualitative and quantitative EEG analysis was performed on digital video-EEG records obtained during 6 months of recording. The main finding of this study was that 5/10 (50%) lesioned animals developed focal epileptic seizures ipsilateral to the cortical infarct characterized by rhythmic spike-wave discharges with or without behavioral change. Epileptic animals demonstrated increased delta, theta, and low beta-range power ipsilateral to the infarct that reliably distinguished them from lesioned nonepileptic and control animals. Lesioned animals (epileptic and nonepileptic) also demonstrated a distinct pattern of focal rhythmic theta activity before or after generalized high beta-range discharges. Electrical and behavioral characteristics common to both lesioned and control animals included: (1) focal rhythmic theta activity in either hemisphere; (2) focal low beta-range discharges in either hemisphere; (3) generalized high beta-range discharges; (4) absence seizures; (5) generalized pseudoperiodic spike discharges associated with mild multifocal body jerks; (6) tonic-clonic seizures (one nai;ve control; one lesioned animal). Cresyl violet staining of lesioned animals' brains showed consistent infarcts of the sensorimotor cortex extending to the subcortical white matter. These results provide an expanded electrobehavioral description of young adult rats following photothrombotic brain infarction and augment further investigation into the molecular, cellular, and network alterations that contribute to the establishment of post-stroke epilepsy.

Asymmetries in Visual-Spatial Processing Following Childhood Stroke

The authors compared hemisphere-based and cognitive-domain-based hypotheses for visual-spatial deficits in children with stroke (n = 33) and children without stroke (n = 43). Children with unilateral left (n = 14) or right (n = 7) injury showed less efficient search for the visual field contralateral to their injury. Right-hemisphere injury was associated with deficient global-level processing and coordinate spatial judgments. Left-hemisphere injury resulted in relatively intact local versus global processing and categorical versus coordinate judgments. Bilateral injury (n = 12) resulted in disruption of visual search across visual fields and relative deficits in global-level processing and coordinate spatial judgments. Recovery of visual-spatial processing in children following childhood stroke is task specific. Certain visual-spatial functions typically mediated by the left hemisphere appear less vulnerable to disruption.