title: Prenatal unilateral cerebellar hypoplasia in a series of 26 cases: significance and implications for prenatal diagnosis.
abstract: OBJECTIVE
  To define imaging patterns of unilateral cerebellar hypoplasia (UCH), discuss possible pathophysiological mechanisms and underline the etiology and prognosis associated with these lesions.
  
  
  METHODS
  In this retrospective study we reviewed the charts of 26 fetuses diagnosed between 2003 and 2011 with UCH, defined by asymmetrical cerebellar hemispheres with or without decreased transverse cerebellar diameter. The review included analysis of the anatomy of the cerebellar hemispheres, including foliation, borders and parenchymal echogenicity, and of the severity of the hypoplasia. Data from clinical and biological work-up and follow-up were obtained.
  
  
  RESULTS
  Our series could be divided into two groups according to whether imaging features changed progressively or remained constant during follow-up. In Group 1 (n = 8), the progression of imaging features, echogenic cerebellar changes and/or hyposignal in T2*-weighted MR images were highly suggestive of ischemic/hemorrhagic insult. In Group 2 (n = 18), imaging features remained constant during follow-up; UCH was associated with abnormal foliation in three proven cases of clastic lesions, a cystic lesion was noted in three cases of PHACE (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac abnormalities/aortic coarctation, eye abnormalities) syndrome and, in the remaining cases, UCH remained unchanged, with no imaging pattern typical of hemorrhage. In 24 cases the infant was liveborn and follow-up was continued in 23, for a mean period of 3 years. Among these, neurological complications were identified in seven (in one of seven (at a mean of 46 months) in Group 1 and in six of 16 (at a mean of 35 months) in Group 2). The surface loss of cerebellar hemisphere was > 50% in 19/24 fetuses and the vermis was clearly normal in appearance in 19/24. Predisposing factors for fetal vascular insult were identified in eight cases: these included maternal alcohol addiction, diabetes mellitus, congenital cytomegalovirus infection and pathological placenta with thrombotic vasculopathy and infarctions.
  
  
  CONCLUSIONS
  UCH is defined as a focal lesion of the cerebellum that may be secondary to hemorrhage and/or ischemic insult, suggesting a clastic origin, particularly when imaging follow-up reveals changes over time. UCH may also be a clue for the prenatal diagnosis of PHACE syndrome. The amount of surface loss of cerebellar hemisphere does not correlate with poor prognosis. UCH with normal vermis is often associated with normal outcome.
authors.affiliation: Centre Pluridisciplinaire de Diagnostic Prénatal, Hôpital Femme Mère Enfant, Université Claude Bernard Lyon I, Lyon, France.
authors.forename: M
authors.initials: M
authors.lastname: Massoud
authors.forename: M
authors.initials: M
authors.lastname: Cagneaux
authors.forename: C
authors.initials: C
authors.lastname: Garel
authors.forename: N
authors.initials: N
authors.lastname: Varene
authors.forename: M-L
authors.initials: ML
authors.lastname: Moutard
authors.forename: T
authors.initials: T
authors.lastname: Billette
authors.forename: A
authors.initials: A
authors.lastname: Benezit
authors.forename: C
authors.initials: C
authors.lastname: Rougeot
authors.forename: J-M
authors.initials: JM
authors.lastname: Jouannic
authors.forename: J
authors.initials: J
authors.lastname: Massardier
authors.forename: P
authors.initials: P
authors.lastname: Gaucherand
authors.forename: V
authors.initials: V
authors.lastname: Desportes
authors.forename: L
authors.initials: L
authors.lastname: Guibaud
mesh_terms: D001017:Aortic Coarctation / Q000000981:diagnostic imaging; D002531:Cerebellum / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000002:abnormalities / Q000000981:diagnostic imaging; D002658:Developmental Disabilities / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D005124:Eye Abnormalities / Q000000981:diagnostic imaging; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D005865:Gestational Age; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009421:Nervous System Malformations / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods; D011379:Prognosis; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods
keywords: PHACE syndrome; cerebellum; clastic lesion; posterior fossa; ultrasound