Late plasticity for language in a child's non-dominant hemisphere: a pre- and post-surgery fMRI study.

International audienceThe ability of the right hemisphere to sustain the acquisition or the recovery of language after extensive damage to the left hemisphere has been essentially related to the age at the time of injury. Better language abilities are acquired when the insult occurs in early childhood (perinatal insults) compared with later occurrence. However, while previous studies have described the neuropsychological pattern of language development in typical cases, the neural bases of such plasticity remain unexplored. Non-invasive functional MRI (fMRI) is a unique tool to assess the neural correlates of brain plasticity through repeated studies, but the technique has not been widely used in children because of methodological limitations. Plasticity of language was studied in a boy who developed intractable epilepsy related to Rasmussen's syndrome of the left hemisphere at age 5 years 6 months, after normal language acquisition. The first fMRI study at age 6 years 10 months showed left lateralization of language networks during a word fluency task. After left hemispherotomy at age 9 years, the child experienced profound aphasia and alexia, with rapid recovery of receptive language but slower and incomplete recovery of expressive language and reading. Postoperative fMRI at age 10 years 6 months showed a shift of language-related networks to the right during expressive and receptive tasks. Right activation was seen mainly in regions that could not be detected preoperatively, but mirrored those previously found in the left hemisphere (inferior frontal, temporal and parietal cortex), suggesting reorganization in a pre-existing bilateral network. In addition, neuropsychological data of this case support the hypothesis of innately more bilateral distribution of receptive than expressive language. This first serial fMRI study illustrates the great plasticity of the child's brain and the ability of the right hemisphere to take over some expressive language functions, even at a relatively late age. It also suggests a limit for removal of the dominant hemisphere beyond the age of 6 years, a classical limit for the critical period of language acquisition

Assessment of everyday executive functioning using the BRIEF in children and adolescents treated for brain tumor

International audienceObjective: Childhood brain tumors (BTs) and their treatment often negatively affect development of executive functions. Previous studies have reported executive functions deficits, particularly through questionnaires of daily life. This study aimed to assess executive functioning in everyday life following pediatric BT, in a larger and more histologically diverse sample than previously, and to study clinical and demographic factors influencing outcome. Methods: Assessment of executive functioning using parent ratings of the Behavior Rating Inventory of Executive Function (BRIEF), in a large sample of children treated for various BT (n = 153). Clinical and demographic factors were: age at diagnostic, age at assessment, parental education level, radiation therapy. Results: Significant difficulties were found in the 3 composite indices and in the majority of the BRIEF subscales. The highest level of difficulties was observed in the Working Memory subscale. Older age at assessment and younger age at diagnosis were significantly associated with higher levels of parent-reported difficulties, particularly for metacognition. Conclusions: Parents of children treated for BT report widespread and persistent deficits in executive functions that negatively affect their everyday functioning. Including analysis of all clinical scales and composite indices allows a more comprehensive approach and enables to specify the patients’ executive profile

Impairment of intellectual functions after surgery and posterior fossa irradiation in children with ependymoma is related to age and neurologic complications

<p>Abstract</p> <p>Background</p> <p>To investigate the neuropsychological outcome of children treated with surgery and posterior fossa irradiation for localized infratentorial ependymoma.</p> <p>Methods</p> <p>23 patients (age 0.3 – 14 years at diagnosis) who were treated with local posterior fossa irradiation (54 Gy) underwent one (4 patients) or sequential (19 patients) neuropsychologic evaluation. The last evaluation was performed at a median of 4.5 (1 to 15.5) years after RT.</p> <p>Results</p> <p>Mean last full scale IQ (FSIQ), verbal IQ (VIQ) and PIQ were 89.1, 94.0, and 86.2 respectively. All patients had difficulties with reading, and individual patients showed deficits in visuospatial, memory and attentional tasks. There was no trend for deterioration of intellectual outcome over time. All 5 children with IQ scores ≤ 75 were under the age of four at diagnosis. There was a significant association between the presence of cerebellar deficits and impaired IQ (72.0 vs 95.2, p < 0,001). The absence of hydrocephalus was an indicator of better neuropsychologic outcome (mean FSIQ of 102.6 vs 83.9, p = 0.025).</p> <p>Conclusion</p> <p>Within the evaluated cohort, intellectual functions were moderately impaired. Markedly reduced IQ scores were only seen with early disease manifestation and treatment, and postoperative neurological deficits had a strong impact on intellectual outcome.</p