Rationale: A child's brain shows a remarkable ability to recover from adverse events such as stroke. Language functions recover particularly well, while visuo-spatial skills are more affected by brain damage, regardless of its localization. This study investigated the lateralization of language and visual search after childhood stroke.
Methods: Ten patients with unilateral stroke (aged 10-19 years, five left-, five right-sided lesion) and 20 healthy controls (aged 8-20 years) completed a neuropsychological test battery and functional magnetic resonance imaging (fMRI) intended to activate predominantly right (visual search) and left-sided functional networks (language).
Results: After stroke, patients demonstrated atypical lateralization of visual search functions (8/10 patients, left lateralization) more often than that of language (4/10 patients, right lateralization). There was a dissociation between the lateralization of productive and semantic language (4/10 patients, 1/20 controls) and between the lateralization of simple and complex visual search (3/10 patients, 3/20 controls). In patients, atypical contralateral activations occurred in the same areas that showed decreasing activation during development in healthy participants.
Conclusion: The lateralization of functions depends upon the cognitive function measured. Dissociation between the lateralization of different language or visual search tasks can occur.