Brain morphometry and psychomotor development in children with PCH2A

Introduction
Pontocerebellar hypoplasia type 2A (PCH2A) is a rare neurogenetic disease characterized by severe cognitive and motor impairment. This study reports on brain morphometry and psychomotor development of affected children.
Materials and methods
We analyzed 78 cerebral MRI datasets of 57 patients with genetically confirmed PCH2A. Volumetric and in-plane measurements were conducted 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 (aged 7 months to 33 years) filled in a survey assessing motor and cognitive development. Developmental status was compared to MRI measurements.
Results
In 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. Longitudinal data did not reveal a decrease in cerebellar volume or in-plane measurements. Supratentorial measurements showed progressive microcephaly and a continuous increase of the Evans index, reflecting progressive cerebral atrophy. Patients demonstrated severe cognitive and motor impairments, with developmental regression reported in only a minority. No statistical relationship between brain measurements and cognitive or motor development was observed.
Conclusion
MRI in PCH2A patients 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 significantly impaired, but regression is rare.