Abstracts

Rationale: Research on the neuropsychological outcomes of hemispherectomy in childhood has focused on the preservation of language development after surgery to the left hemisphere. That work has highlighted the positive aspects of neural plasticity and the crowding effect, where language functioning is transferred to the right hemisphere and aspects of visual-spatial processing may suffer.  Less is known about the effects of right hemispherectomy on cognitive development, with existing studies including samples that vary considerably in etiology, age of seizure onset, duration of epilepsy, and age at surgery. Here we present a case of a right hemispherectomy very early in life, allowing for an extended period of seizure-free development of the left hemisphere.

Methods: A comprehensive neuropsychological assessment was administered to a 6-year-old boy who underwent a right hemispherectomy at 6 months of age in the context of right-sided hemimegaloencephaly and seizures.

Results: Testing revealed average language and verbal intellectual skills in contrast to significant difficulty with visual-spatial skills, non-verbal reasoning, visuomotor processing speed and visuomotor integration. Working memory, verbal and visual recall, and ratings of adaptive behaviour were intact. Academic skills were in the low average range. Parents reported inattention and academic struggles.

Conclusions: These results illustrate that the isolated left hemisphere can capably support the development of language and verbal reasoning abilities. There is little evidence for plasticity of the left hemisphere to take on the visual-spatial skills typically associated with the right hemisphere. This case illustrates the prioritization and limitations of plasticity for cognitive development.

Funding: The Hospital for Sick Children Foundation