Duc Ha Hoang, Anne Pagnier, Emilie Cousin,
Introduction: Medulloblastomas are the most common malignant childhood brain tumors arising in the posterior fossa. As a result of advances in treatment the number of survivors has increased significantly. In this study, children treated for a cerebellar medulloblastoma demonstrated cognitive disorders in working memory, especially the visuospatial component, leading to impairments in school performance. This study aims to describe the cerebellar involvement in specific cognitive deficits observed in these children.
Method: Nine healthy volunteer children (11.1 ± 2.2 years old), were compared to 5 patients treated for cerebellar medulloblastoma (12.3 ± 0.7 years old). All subjects were native French speakers, right-handed, with a global Intelligence Quotient (IQ) of 70-130. Stimuli were presented to the participants with alternating the sensory modality (visual, auditory) and the nature of communication (verbal, nonverbal) in a blocked 1-back design during functional Magnetic Resonance Imaging (fMRI) acquisitions. Results were analyzed using a Mann-Whitney U test for neuropsychological and behavioral data; SPM8 (Statistical Parametric Mapping) and SUIT (Spatially Unbiased Atlas Template) for anatomical and functional MRI data.
Results: Non-verbal working memory deficit was demonstrated in 4 of the 5 children treated for medulloblastoma. The 4 patients with working memory deficit all had surgery to the left posterior cerebellar lobe. The only patient without any working memory disorders did not have hemispheric cerebellar resection. Neuronal activations for nonverbal versus verbal contrast and visual versus auditory contrast were stronger in the left posterior cerebellar lobe. Brain activations in healthy subjects were consistent with the findings previously described in literature.
Conclusion: The cerebellum plays the same role in working memory in children as that has been previously described in adults. The left posterior cerebellar lobe may involve the visuospatial working memory. Based on neuroimaging and clinical studies, attention should be paid to avoid or limit the damage of the posterior cerebellar lobe to minimize cognitive deficits and improve the quality of life for children.