Literacy-related skills among children after left or right hemispherectomy.

OBJECTIVE: Following hemispherectomy surgery, children's educational outcomes are of great importance but are understudied. The study goal was to investigate reading, language, and nonverbal cognitive skills in children obligatorily relying on a left versus right hemisphere using a cross-sectional design. METHODS: Participants (ages 6-18) who had undergone left hemispherectomy (LH; n = 10) or right hemispherectomy (RH; n = 14) completed standardized measures of reading, language, and nonverbal cognition. RESULTS: LH and RH groups were balanced for socioeconomic status, sex, and age. Both groups scored below the population mean across standardized measures (RH: -0.79 to -1.95 SDs; LH: -0.97 to -2.32 SDs). Compared to the LH group, the group retaining a functional left hemisphere (RH group) learned to read sooner (p = .011) despite no significant differences for surgery age, and scored higher on untimed real word and pseudoword reading measures (p < .05). Effect sizes were medium (r = 0.34-0.46) for the LH and RH comparison on measures of phonological awareness and both untimed and timed word and pseudoword reading. In examining the association between clinical variables and reading-related outcomes, younger age of post-hemispherectomy reading acquisition and shorter duration between seizure onset and hemispherectomy surgery were associated with higher standardized reading and language test scores (p < .05). SIGNIFICANCE: Investigations of psychoeducational skills in reading, language, and nonverbal cognition among children who have undergone hemispherectomy can offer important insights into compensatory potential for left and right hemispheres as well as inform educational programming for children following medical stabilization.

Dissociating executive function and ADHD influences on reading ability in children with dyslexia.

Developmental dyslexia (DD) and attention-deficit/hyperactivity disorder (ADHD) are two of the most common neurodevelopmental disorders among school-age children. These disorders frequently co-occur, with up to 40-50% of children with one diagnosis meeting criteria for the other, and similar percentages of children with either DD or ADHD exhibiting impaired executive functions (EF). Although both ADHD and EF deficits are common in dyslexia, there is little evidence about how ADHD and EF deficits specifically influence the brain basis of reading difficulty in dyslexia, and whether the influences of ADHD and EF on dyslexia can be disentangled. The goal of the current study was to investigate, at both behavioral and brain levels, whether reading performance in individuals with dyslexia is more strongly associated with EF or with diagnostic status of comorbid ADHD. We examined reading abilities and EF in children (8-13 years old) with typical reading ability, DD only, or both DD + ADHD. Across both groups with dyslexia, impaired EF was associated with greater impairment on measures loading onto a reading fluency, but not a reading accuracy, factor. There were no significant differences between the DD and DD + ADHD groups on measures of reading fluency or reading accuracy. During functional magnetic resonance imaging (fMRI) while performing a rhyme-matching reading task requiring phonological awareness, typically developing readers showed greater left-hemisphere reading network activation than children with DD or DD + ADHD. Children with DD and DD + ADHD did not show differential activation, but DD children with unimpaired EF showed greater activation than those with impaired EF in reading-related areas. Thus, ADHD status alone had no measurable influence on reading performance or brain activation. Impaired EF in dyslexia, independent of ADHD status, was associated with greater deficits in reading fluency and greater reductions of activation in response to print in the typical left-hemisphere reading network.