Plasticity in the developing brain: intellectual, language and academic functions in children with ischaemic perinatal stroke

Abstract

The developing brain has the capacity for a great deal of plasticity. A number of investigators have demonstrated that intellectual and language skills may be in the normal range in children following unilateral perinatal stroke. Questions have been raised, however, about whether these skills can be maintained at the same level as the brain matures. This study aimed to examine the stability of intellectual, academic and language functioning during development in children with perinatal stroke, and to resolve the inconsistencies raised in previous studies. Participants were 29 pre-school to school-age children with documented unilateral ischaemic perinatal stroke and 24 controls. Longitudinal testing of intellectual and cognitive abilities was conducted at two time points. Study 1 examined IQ, academic skills and language functions using the same test version over the test-retest interval. Study 2 examined IQ over a longer test-retest interval (pre-school to school-age), and utilized different test versions. This study has resulted in important new findings. There is no evidence of decline in cognitive function over time in children with perinatal unilateral brain damage. These results indicate that there is sufficient ongoing plasticity in the developing brain following early focal damage to result in the stability of cognitive functions over time. Also, the presence of seizures limits plasticity such that there is not only significantly lower performance on intellectual and language measures in the seizure group (Study 1), but the course of cognitive development is significantly altered (as shown in Study 2). This study provides information to support the notion of functional plasticity in the developing brain; yields much-needed clarification in the literature of prognosis in children with early ischaemic perinatal stroke; provides evidence that seizures limit plasticity during development; and avoids many of the confounds in prior studies. A greater understanding of how children with ischaemic perinatal stroke fare over time is particularly important, as there has been conflicting information regarding prognosis for this population. It appears that when damage is sustained very early in brain development, cerebral functional reorganization acts to sustain a stable rate of development over time.

Factors affecting cognitive outcome in early pediatric stroke

“…Contrary to the nonexistent laterality effect on outcome, we confirmed a negative influence of acute and persisting seizures on cognitive outcome. 10,22 However, while poor cognitive outcome in the youngest age group is certainly influenced by the existence of seizures, it cannot solely be explained by this factor.…”

“…[4][5][6] Based on animal and human studies and according to the "early plasticity thesis," the developing brain is plastic and thus more capable of reorganization after an insult than the adult brain. [7][8][9][10] However, younger age at stroke is associated with poorer intellectual outcome and a broader spectrum of dysfunctions across multiple neuropsychological domains. 6,[11][12][13][14][15][16][17] Further, children with combined cortical and subcortical lesions have overall poorer cognitive outcome, 16,18 and larger lesion size negatively influences cognitive and functional outcome, 4,19,20 possibly due to disruption of more neural network connections, adversely affecting functional brain organization.…”

“…21 Regarding lesion laterality, controversial reports exist concerning the effect of lesion laterality on neuropsychological outcome. [11][12][13]15,16,22 In addition, persistent seizures 10,22 and persistent NI such as hemiplegia/paresis or visual field deficits also negatively influence neuropsychological and functional outcome. 5,11,19 The main goal of this study was to examine the influence of age, lesion characteristics, seizures, NI, and functional outcome on cognitive outcome in a population-based group of children 2 years after an AIS occurrence.…”

VEGF reverts the cognitive impairment induced by a focal traumatic brain injury during the development of rats raised under environmental enrichment

“…This time lapse is enough to repair the surrounding tissue, thus recovering from injuries induced by minipump implantation. In addition, focal small lesions such as the one produced by cannula implantation can be repaired easily [50].…”

Imaging selective vulnerability in the developing nervous system

“…In addition, functional outcomes are affected from disturbance of these pathways. It is commonly believed that the newborn brain is plastic and resilient but followup human studies have provided mixed results (Ballantyne et al 2008;Ment et al 2009b). However, it has been learned from animal studies that the newborn brain can repair itself through enhanced neurogenesis (Gonzalez et al 2007).…”