Objectives: We report clinical and paraclinical features of a patient with an original unilateral
hemispheric malformation of cerebellum.
Methods: Clinical features, neuropsychological testing, neuroradiological, electrophysiological,
metabolic and genetic investigations were performed.
Results: This girl is the only child of non consanguineous French Canadian parents. The first
neurological examination was performed when she was 2.5 years old and showed a global
psychomotor delay (Denver test; DQ=60%). She started to walk at 23 months. Ataxic
gait was then observed. She was dysarthric. At the age of 3.5 years, speech remained
immature (phonology, syntax). A non-progressive macrocephaly was noticed. Brain MRI
at 2.5 years showed a diffusely prominent left cerebellar hemisphere. EEG, genetic
and metabolic studies were normal. Brain MRI of the parents was normal.
Conclusion: We reported for the first time to our knowledge, an hemispheric cerebellar dysplasia
characterized by an “ hemimegacerebellum ” appearance in brain MRI investigation.
