title: Brain morphometry in Pontocerebellar Hypoplasia type 2.
abstract: Pontocerebellar hypoplasia type 2 (PCH2) is caused by a defect in the TSEN54-gene and leads to severe and early disruption of brain development, especially of cerebellum and pons. The aim of this work was to quantify the infra- and supratentorial brain growth during postnatal brain development in children with PCH2.
  
  
  
  MRI data of 24 children with PCH2 (age 0.02-17 years., 13 females) were analysed volumetrically and compared to images of 24 typically developing age- and gender-matched children. All children with PCH2 had the homozygous p.A307S mutation in the TSEN54-gene. In 5 patients follow-up MRI investigations were available. Images of the children with PCH2 were available either on film (n = 12) or in digital format (n = 21). Images on film were digitalized. Brain structures were manually masked and further adjusted semi-automatically using intensity thresholding to exclude CSF. Volumes of cerebellum, brain stem, and pons were measured, as well as supratentorial brain and frontal lobe volume. For validation of the method part of the digital images were processed as images on film. In addition, intra- and inter-rater variabilities were tested.
  
  
  
  Children with PCH2 showed reduced volumes of all measured brain structures compared to healthy controls. Severely hypoplastic cerebellum, pons and brain stem only slightly increased in size postnatally. Supratentorial brain volume also showed reduced growth compared to the healthy controls. Differences between patients and controls could already be seen at birth but became more significant during childhood. Validation of the method showed high precision and reproducibility.
  
  
  
  In a genetically very homogenous group of children with PCH2 severely hypoplastic infratentorial structures, the hallmark of the disease, showed only slight increase in volume postnatally. Supratentorial brain structures, which are considered normal at birth, also showed smaller volumes neonatally and a lower growth rate compared to controls, leading to severe microcephaly. Volume loss, however, could not be observed during the first years of life. This argues for a severe disruption of the cerebellar-cerebral networks during pre- and postnatal development caused by a primary cerebellar dysfunction, rather than postnatal neurodegeneration. The developmental progress in these children, although little, further supports this.
authors.affiliation: Department of Child Neurology, Children's Hospital, University of Tübingen, Hoppe-Seyler-Str. 1, 72072, Tübingen, Germany.
authors.forename: Kaspar
authors.initials: K
authors.lastname: Ekert
authors.affiliation: Department of Child Neurology, Children's Hospital, University of Tübingen, Hoppe-Seyler-Str. 1, 72072, Tübingen, Germany.
authors.forename: Samuel
authors.initials: S
authors.lastname: Groeschel
authors.affiliation: Department of Child Neurology, Children's Hospital, University of Tübingen, Hoppe-Seyler-Str. 1, 72072, Tübingen, Germany. iciar.sanchez@med.uni-tuebingen.de.
authors.forename: Iciar
authors.initials: I
authors.lastname: Sánchez-Albisua
authors.affiliation: Department of Child Neurology, Children's Hospital, University of Tübingen, Hoppe-Seyler-Str. 1, 72072, Tübingen, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: Frölich
authors.affiliation: Department of Neuropediatrics, Jena University Hospital, Bachstraße 18, 07743, Jena, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Dieckmann
authors.affiliation: Department of Child Neurology, Children's Hospital, University of Tübingen, Hoppe-Seyler-Str. 1, 72072, Tübingen, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Engel
authors.affiliation: Department of Child Neurology, Children's Hospital, University of Tübingen, Hoppe-Seyler-Str. 1, 72072, Tübingen, Germany.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Krägeloh-Mann
mesh_terms: D000293:Adolescent; D001921:Brain / Q000473:pathology*; D001933:Brain Stem / Q000473:pathology; D016022:Case-Control Studies; D002531:Cerebellum / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008831:Microcephaly / Q000473:pathology; D009849:Olivopontocerebellar Atrophies / Q000473:pathology*; D011149:Pons / Q000473:pathology
keywords: Brain morphometry; Brain stem; Cerebellum; Frontal lobe; Mental retardation; Microcephaly; Pons; Pontocerebellar hypoplasia type 2