IntroductionPontocerebellar hypoplasia type 2A (PCH2A) is a rare neurogenetic disease causing severe cognitive and motor impairment. We report on brain morphometry and psychomotor development of affected children.Materials and MethodsWe analyzed 78 cerebral MRI datasets of 57 patients with genetically proven PCH2A. Volumetry and in-plane measurements were performed in cerebellum, neocortex and pons. Supratentorial width and width of the anterior horns of the lateral ventricles was used to calculate the Evans index.Caregivers of 65 patients with PCH2A (7 months to 33 years) filled in a survey assessing motor and cognitive development. Developmental status was compared to MRI measurements.ResultsIn children with PCH2A, cerebellar volume was markedly smaller than in healthy children at birth, with slower increase and stagnation at around 12 months. No cerebellar growth was observed in the cranio-caudal axis. Long-term data did not show a decrease in cerebellar volume or in-plane measurements. Supratentorial measurements showed progressive microcephaly and a continuous increase of the Evans index, indicating progressive cerebral atrophy. Patients showed severely impaired cognitive and motor development. Developmental regression was reported only for a minority. No statistical relationship between brain measurements and cognitive or motor development was observed.ConclusionMRI of patients with PCH2A shows limited cerebellar growth during infancy, especially restricted along the cranio-caudal axis. After infancy, cerebellar volume remains relatively stable. Supratentorial measurements indicate slowly progressive atrophy. Psychomotor development is severely impaired, but regression is rare.Highlights-MRI (57 patients) and developmental data (65 patients) of children with PCH2A-Cerebellar growth is affected in a spatial manner, resulting in the dragonfly sign-Ongoing supratentorial atrophy, potentially secondary to cerebellar pathology-Psychomotor development is delayed, but takes place and regression is rare-No relation between brain measurements and developmental trajectories