title: Early formative stage of human focal cortical gyration anomalies: fetal MRI.
abstract: OBJECTIVE
  Limited information is available about the development of focal cortical gyration anomalies in the human brain. Using prenatal MRI, we characterized focal cortical gyration anomalies at an early formative stage and sought clues about the mechanisms of their development.
  
  
  METHODS
  From a large prenatal MRI database, 30 cases (gestational age, ≤ 24 weeks) with reported focal distortion of the cortical rim profile were selected. Eight cases were matched with histologic examinations; another seven had prenatal MRI, MRI autopsy, or postnatal MRI follow-up; and 15 had no follow-up but did present analogous abnormal cortical features. Focal cortical gyration anomalies were detectable when the brain was still smooth (i.e., physiological lissencephaly).
  
  
  RESULTS
  Four patterns of cortical plate anomaly were identified: wartlike (11 cases), abnormal invaginating sulcus (11 cases), sawtooth (six cases), and single or multiple bumps (two cases). A thinned or blurred subplate and intermediate zone in the focal cortical gyration anomaly site was detected in 80% of cases. All but two cases had other intracranial anomalies. Seven cases were classified as hypoxic-ischemic, five as genetic, and three as infective. In 15 cases, the cause could not be established. In five fetuses with further intrauterine or postnatal MRI, focal cortical gyration anomalies increased in complexity, fulfilling postnatal imaging criteria of polymicrogyria.
  
  
  CONCLUSIONS
  Focal cortical gyration anomalies can be detected at the early sulcation process stage. The process leading to abnormal gyration may evolve faster than physiologic ones and seems to be related to alterations of parenchymal layering occurring before 24 weeks' gestation. Most focal cortical gyration anomalies evolve toward what is currently considered polymicrogyria.
authors.affiliation: Department of Radiology and Neuroradiology, Children's Hospital V. Buzzi, Via Castelvetro 32, Milan 20154, Italy. neurorad@icp.mi.it
authors.forename: Andrea
authors.initials: A
authors.lastname: Righini
authors.forename: Cecilia
authors.initials: C
authors.lastname: Parazzini
authors.forename: Chiara
authors.initials: C
authors.lastname: Doneda
authors.forename: Laura
authors.initials: L
authors.lastname: Avagliano
authors.forename: Filippo
authors.initials: F
authors.lastname: Arrigoni
authors.forename: Mariangela
authors.initials: M
authors.lastname: Rustico
authors.forename: Dario
authors.initials: D
authors.lastname: Consonni
authors.forename: Thomas Joseph
authors.initials: TJ
authors.lastname: Re
authors.forename: Gaetano
authors.initials: G
authors.lastname: Bulfamante
authors.forename: Fabio
authors.initials: F
authors.lastname: Triulzi
mesh_terms: D001921:Brain / Q000002:abnormalities*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D054220:Malformations of Cortical Development / Q000175:diagnosis*; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies