title: Potential mechanisms of cerebellar hypoplasia in prematurity.
abstract: BACKGROUND
  The cerebellum undergoes dramatic growth and maturation over the neonatal period after preterm birth and is thus particularly sensitive to impaired development due to various clinical factors.
  
  
  METHODS
  Impairments in growth can occur independent of cerebellar parenchymal damage, such as from local hemorrhage, resulting from reduced expression of sonic hedgehog signaling to trigger the appropriate expansion of the granule precursor cells.
  
  
  RESULTS
  The primary risk factors for impaired cerebellar development include postnatal glucocorticoid exposure, which has direct effects on the sonic hedgehog pathway, and supratentorial brain injury, including intraventricular hemorrhage and white matter injury, which may result in crossed cerebellar diaschisis and local toxic effects of blood products on the external granular layer. Other cardiorespiratory and nutritional factors may also exist. Impaired cerebellar development is associated with adverse outcomes in motor and cognitive development.
  
  
  CONCLUSIONS
  New approaches to care to counteract these risk factors may help improve long-term outcome after preterm birth.
authors.affiliation: Division of Neurology, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, Canada. emily.tam@sickkids.ca
authors.forename: Emily W Y
authors.initials: EW
authors.lastname: Tam
mesh_terms: D002531:Cerebellum / Q000002:abnormalities* / Q000503:physiopathology*; D002658:Developmental Disabilities / Q000453:epidemiology / Q000503:physiopathology; D019317:Evidence-Based Medicine; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology* / Q000503:physiopathology*; D008959:Models, Neurological; D009421:Nervous System Malformations / Q000453:epidemiology* / Q000503:physiopathology*; D012307:Risk Factors