Inhibitory Control in Children with Frontal Infarcts Related to Sickle Cell Disease

Evidence from past studies indicates that children with traumatic brain injury experience difficulties with inhibitory control. Less is known about inhibitory control in children with frontal brain injury related to cerebral infarction. We compared the inhibitory performance of children with frontal infarcts related to sickle cell disease with that of a control group of children with sickle cell disease but no history of cerebral infarction. On a stimulus-response reversal task, children with frontal infarcts made significantly more accuracy errors in the inhibitory condition than controls. Findings from this study and from previous research suggest that impairments in inhibitory control are common following frontal injury in a range of pediatric populations.     

Neuropsychologic Deficits in Children with Sickle Cell Disease and Cerebral Infarction: Role of Lesion Site and Volume

Little is known about the correlation between the location and size of cerebral infarction in children and neuropsychologic deficits. We related lesion location and volume on magnetic resonance exams to neuropsychologic performance in 28 children with cerebral infarcts due to sickle cell disease. Seventeen healthy siblings served as a comparison group. Children with anterior cerebral infarcts (n = 7) showed deficits in attention and executive skills, whereas children with more widespread cerebral infarcts (n = 18) showed additional deficits in spatial skills. The volume of cerebral infarction was associated with spatial and language performance, but minimally related to performance in other cognitive domains. The location and volume of cerebral infarction are both important for defining the type and magnitude of cognitive sequelae in childhood stroke.     

Etiology of strokes in children with sickle cell anemia

The most devastating complication of sickle cell anemia is cerebral infarction, affecting approximately 30% of all individuals with sickle cell anemia. Despite being one of the most common causes of stroke in infants and children, the mechanism of cerebral infarction in this population has not been extensively studied and is poorly understood. Multiple, synergistic factors are important in the pathogenesis of stroke including the hemodynamic effects of cerebral arterial occlusive disease, viscosity, chronic and acute anemia and acute medical events. This review focuses on the relationship between these factors in order to provide a foundation for further study of the etiology of strokes in this high-risk population.     

Impairment and recovery in inhibitory control after traumatic brain injury in children: effect of age at injury, injury severity and lesion location

We examined the effect of traumatic brain injury (TBI) on inhibitory control, trajectories of recovery of inhibitory control, and the effect of age at injury, severity, and lesion location on recovery. Participants were 127 children with TBI aged 5-16 years and 117 controls of similar age.Latency of response inhibition was measured with the stop signal task within 1 month of the injury and again at 3, 6, 12, and 24 months.Performance of children with TBI was compared with that of controls.Growth curve analyses showed impairments in response inhibition postinjury.Compared with controls, TBI children improved over time in response inhibition. Younger TBI children recovered better on response inhibition than older TBI children. No significant effect of severity or right frontal lesion on recovery of response inhibition was found. TBI has an acute effect on inhibitory control but which recovers over time.     

Response inhibition in children with and without ADHD after traumatic brain injury

Children with attention‐deficit hyperactivity disorder (ADHD) and traumatic brain injury (TBI) show deficient response inhibition. ADHD itself is a common consequence of TBI, known as secondary ADHD (S‐ADHD). Similarity in inhibitory control in children with TBI, S‐ADHD, and ADHD would implicate impaired frontal‐striatal systems; however, it is first necessary to delineate similarities and differences in inhibitory control in these conditions. We compared performance of children with ADHD and those with TBI without pre‐injury ADHD on a stop signal, response inhibition task. Participants were 274 children aged 6–14 years. There were 92 children with ADHD, 103 children with TBI, and 79 typically developing children who served as controls. Among the TBI participants, injury severity ranged from mild to severe. Children with ADHD and TBI showed deficient inhibition. The deficit in children with ADHD was as great as or greater than that in children with TBI, regardless of degree of TBI severity or the presence of S‐ADHD. The finding indicates that TBI results in deficient inhibition regardless of the development of S‐ADHD.     

Attention deficits in children with sickle cell disease

Previous research has suggested that children with sickle cell disease may exhibit cognitive deficits even in the absence of direct cerebrovascular involvement (stroke). This study was designed to assess specific attentional deficits in children with sickle cell disease. 12 children with sickle cell disease (Hb SS) with a prior history of stroke, 14 children with sickle cell disease (Hb SS) without evidence of stroke, and 13 similar aged siblings (Hb AA or Hb AS) were compared on measures of attention, intellectual functioning, achievement, and adaptive functioning. Significant differences were found between children with sickle cell disease (with or without stroke) and healthy controls on a timed test of visual scanning, the Coding subtest of the Wechsler Intelligence Scale for Children-Revised, and subtests of Reading, Arithmetic, and Spelling from the Wide Range Achievement Test-Revised. The differences between children with sickle cell disease and their healthy siblings appear to be the result of strokes rather than sickle cell disease itself as children with sickle cell disease without strokes did not significantly differ from controls. Implications for the effects of sickle cell disease and stroke on academic performance are discussed.     

Physiological correlates of intellectual function in children with sickle cell disease: hypoxaemia, hyperaemia and brain infarction

Lowered intelligence relative to controls is evident by mid-childhood in children with sickle cell disease. There is consensus that brain infarct contributes to this deficit, but the subtle lowering of IQ in children with normal MRI scans might be accounted for by chronic systemic complications leading to insufficient oxygen delivery to the brain. We investigated the relationship between daytime oxyhaemoglobin saturation (SpO2), cerebral blood flow velocity (CBFV) and intellectual function (IQ) using path-analysis in 30 adolescents with sickle cell disease (mean age 17.4 years, SD 4.2). Initial analyses revealed that the association between SpO2 and Full Scale IQ (FSIQ) was fully mediated by increased CBFV, whereby SpO2 was negatively correlated with CBFV and CBFV was negatively correlated with FSIQ, i.e. decreases in oxygen saturation are associated with increases in velocity, and increased velocity is associated with lowered IQ scores. The mediated relationship suggests that lowered IQ may be a function of abnormal oxygen delivery to the brain. Further analyses showed that the association between CBFV and IQ was significant for verbal but not for performance IQ. The pathophysiology characteristic of SCD can interfere with brain function and constrain intellectual development, even in the absence of an infarct. This supports the hypothesis that lowered intellectual function is partly explained by chronic hypoxia, and has wider implications for our understanding of SCD pathophysiology.     

Neurocognitive sequelae of pediatric sickle cell disease: a review of the literature.

This literature review summarizes all studies relating neuropsychological performance to neuroimaging findings in pediatric sickle cell disease (N=28; published 1991-2005). Although inconsistencies exist within and across domains, deficits in intelligence (IQ), attention and executive functions, memory, language, visuomotor abilities, and academic achievement have been identified. Overall neurocognitive compromise was revealed to be related to the level of neurological injury and the location of silent infarct. Attentional and executive dysfunction is prevalent and related to frontal lobe abnormalities.     

Neurocognitive Sequelae of Pediatric Sickle Cell Disease: A Review of the Literature

This literature review summarizes all studies relating neuropsychological performance to neuroimaging findings in pediatric sickle cell disease (N=28; published 1991–2005). Although inconsistencies exist within and across domains, deficits in intelligence (IQ), attention and executive functions, memory, language, visuomotor abilities, and academic achievement have been identified. Overall neurocognitive compromise was revealed to be related to the level of neurological injury and the location of silent infarct. Attentional and executive dysfunction is prevalent and related to frontal lobe abnormalities.     

Central nervous system complications of sickle cell disease in children: an overview.

Complications involving the central nervous system are among the most devastating manifestations of sickle cell disease. Although overt stroke occurs in 1 in 10 children with Hemoglobin SS, "silent cerebral infarcts" are even more frequent. Both are associated with significant neuropsychological deficits. The end result of these effects on the CNS often is diminished school performance. The use of transcranial Doppler ultrasonography screening allows the identification of patients at high risk for clinical stroke as well as stroke prevention by chronic transfusion. However, definitive prophylaxis and treatment for most CNS complications of sickle cell disease have yet to be determined.     

Central Nervous System Complications of Sickle Cell Disease in Children: An Overview

Complications involving the central nervous system are among the most devastating manifestations of sickle cell disease. Although overt stroke occurs in 1 in 10 children with Hemoglobin SS, “silent cerebral infarcts” are even more frequent. Both are associated with significant neuropsychological deficits. The end result of these effects on the CNS often is diminished school performance. The use of transcranial Doppler ultrasonography screening allows the identification of patients at high risk for clinical stroke as well as stroke prevention by chronic transfusion. However, definitive prophylaxis and treatment for most CNS complications of sickle cell disease have yet to be determined.     

Frontal cortex functioning in the infant broader autism phenotype

Atypical attention has been proposed as a marker of the broader autism phenotype. In the present study we investigated this and the related process of inhibitory control at the youngest possible age through the study of infant siblings of children with an autism spectrum disorder (Sibs-ASD). Both attention and inhibition have been related to the frontal cortex of the brain. Nine- to ten-month-old Sibs-ASD and low-risk control infants completed the Freeze-Frame task, in which infants are encouraged to inhibit looks to peripherally presented distractors whilst looking at a central animation. The attractiveness of the central stimulus is varied in order to investigate the selectivity of infants’ responses. In line with previous studies, it was found that a subset of Sibs-ASD infants had difficulty disengaging attention from a central stimulus in order to orient to a peripheral stimulus. The Sibs-ASD group also showed less Selective Inhibition than controls. However, Sibs-ASD infants did demonstrate Selective Inhibitory Learning. These results provide preliminary evidence for atypical frontal cortex functioning in the infant broader autism phenotype.     

Affective aprosodia from a medial frontal stroke

BACKGROUND AND OBJECTIVES: Whereas injury to the left hemisphere induces aphasia, injury to the right hemisphere's perisylvian region induces an impairment of emotional speech prosody (affective aprosodia). Left-sided medial frontal lesions are associated with reduced verbal fluency with relatively intact comprehension and repetition (transcortical motor aphasia), but persistent affective prosodic defects associated with right medial frontal lesions have not been described. METHODS: We assessed the prosody of a man who sustained a right medial frontal cerebral infarction seven years prior. RESULTS: While propositional speech expression was normal including syntactic prosody, the patient was impaired at expressing emotions using prosody. His comprehension and repetition of prosody were also impaired but less so than expression. CONCLUSIONS: Right medial frontal lesions can induce an affective aprosodia that primarily impairs expression.     

Resilience in siblings of children with sickle cell disease

This pilot study was conducted to identify factors responsible for promoting resilience in siblings of children with sickle cell disease. Twenty siblings (10–17 years of age) of children (5–13 years) with sickle cell disease were selected from the Pediatric Clinic of Howard University Center for Sickle Cell Disease. The siblings responded to questionnaires, and the data obtained was analyzed by chi-square for association. The results indicated that age, birth order, and gender had no effect on resilience in the siblings. However, family size, number of parents in the home, sibling's knowledge of the illness, degree of morbidity of the illness, socioeconomic status of the family, and parents' attitudes and childrearing practices were all found to affect resilience. These findings provide additional insight into the psychosocial aspects of, and genetic counseling for sickle cell disease, as well as for other chronic genetic disorders.     

The association of oral hydroxyurea therapy with improved cognitive functioning in sickle cell disease.

This study examined potential cognitive benefits of oral hydroxyurea therapy for children with sickle cell disease (SCD). Cognitive abilities of 15 children with SCD on hydroxyurea were compared to 50 other children with SCD, controlling for demographics and hematocrit. Children on hydroxyurea scored significantly higher on tests of verbal comprehension, fluid reasoning, and general cognitive ability than children not on the drug. The data therefore provide preliminary evidence of cognitive benefits of hydroxyurea. Mechanisms for this effect may be improved blood/oxygen supply to the brain or reduced fatigue and illness.     

额叶区域的经颅直流电刺激对抑制控制的影响

抑制控制是执行功能的重要组成部分之一, 研究表明抑制控制与额叶区域的活动有关。经颅直流电刺激(Transcranial Direct Current Stimulation, tDCS)是一种非侵入性的脑刺激技术, 可以调节脑区的激活程度。研究表明tDCS刺激额叶的部分区域可以有效干预参与者的抑制控制水平, 而这一干预作用会受到刺激位置、刺激类型以及实验任务等条件变化的影响。目前tDCS已应用于不同人群的抑制控制研究, 并能与其他研究技术较好的结合。     

SUPPORT FOR A NEUROPSYCHOLOGICAL MODEL OF SPIRITUALITY IN PERSONS WITH TRAUMATIC BRAIN INJURY

Recent research suggests that spiritual experiences are related to increased physiological activity of the frontal and temporal lobes and decreased activity of the right parietal lobe. The current study determined if similar relationships exist between self‐reported spirituality and neuropsychological abilities associated with those cerebral structures for persons with traumatic brain injury (TBI). Participants included 26 adults with TBI referred for neuropsychological assessment. Measures included the Core Index of Spirituality (INSPIRIT); neuropsychological indices of cerebral structures: temporal lobes (Wechsler Memory Scale‐III), right parietal lobe (Judgment of Line Orientation), and frontal lobes (Trail Making Test, Controlled Oral Word Association Test). As hypothesized, spirituality was significantly negatively correlated with a measure of right parietal lobe functioning and positively correlated (nonsignificantly) with measures of left temporal lobe functioning. Contrary to hypotheses, correlations between spirituality and measures of frontal lobe functioning were zero or negative (and nonsignificant). The data support a neuropsychological model that proposes that spiritual experiences are related to decreased activity of the right parietal lobe, which may be associated with decreased awareness of the self (transcendence) and increased activity of the left temporal lobe, which may be associated with the experience of specific religious archetypes (religious figures and symbols).     

Interrupting neural pathways that transduce stressful information into physiological responses.

Stressor-stimuli evoke a noradrenergic process in the frontal lobes, the amplitude of which depends on both the individual's experience with the stimulus and his or her genetic background. Novel and noxious stimuli evoke large frontocortical responses and benign ones evoke relatively larger reactions in persons with a family history of cardiovascular disease. Blockade of neural projections from the frontal cortex and amygdala to the brainstem cardiovascular centers will normalize blood-pressure elevations in experimental hypertension and prevent lethal arrhythmias in animals with a myocardial infarction. The anti-mortality effect of the cardiac drugs known as beta-blockers is exerted by inhibition of cerebral beta-receptors, not peripheral ones. A new putative neuropeptide, NLX, may have the same desirable cardiovascular effects, but without the side-effects that limit clinical usefulness. The neural regulation of the heart during stress can be detected by a new deterministic measure of low-dimensional chaos in heartbeat intervals. In both animals and humans undergoing myocardial infarction, this deterministic measure correctly predicts lethal arrhythmogenesis, minutes to hours prior to the event. Thus an approach combining both brain and heart studies (i.e., "neurocardiology") has led to an understanding of how stressor-stimuli evoke autonomic reactions. This, in turn, has led to new methods in the diagnosis and treatment of cardiovascular disorders.     

Risk factors for arterial ischemic stroke in childhood

Stroke affects up to 13 of 100,000 children, is more common in boys and African Americans, and is associated with considerable cognitive and psychiatric morbidity, as well as motor disability. Around half are hemorrhagic and half are ischemic. Underlying conditions include sickle cell disease, cardiac abnormalities, chromosomal abnormalities (eg, Down syndrome), and neurocutaneous conditions (eg, neurofibromatosis), but up to half the patients with ischemic stroke have no previously diagnosed condition. Although there is almost certainly an important genetic component to stroke risk, head trauma, infections, drugs and radiation appear to play an etiological role in some patients. The majority of the patients with infarction in an arterial distribution have associated cerebrovascular disease. Vascular pathologies include carotid or vertebrobasilar dissection, intracranial vasculopathy affecting the middle and anterior cerebral arteries, which is often transient, and moyamoya. Intermediate risk factors may include hypertension, hypoxia, and poor nutrition leading, for example, to iron deficiency and hyperhomocysteinemia. Some chronic conditions may directly influence the child's behavior and stroke recurrence risk, although large cohorts and randomized controlled trials will be needed before strategies for modification can be evidence-based.     

脑梗死急性期应重视高血糖的处理

脑梗死急性期往往可以检测到血糖升高,而高血糖与脑梗死的转归不良有关。脑梗死急性期高血糖的机制不仅为应激性血糖增高,还可能是多种因素共同作用的结果。注射胰岛素治疗不仅可降低血糖,而且通过对脑组织的直接保护作用减轻脑组织损伤。