title: Aberrant supracallosal longitudinal bundle: MR features, pathogenesis and associated clinical phenotype.
abstract: OBJECTIVE
  To describe the MRI and structural features of a peculiar malformation of the corpus callosum (CC) in a group of young patients with intellectual disability.
  
  
  METHODS
  We studied with conventional MRI and DTI a group of subjects showing an aberrant supracallosal bundle, characterized by the presence of a triangle-shaped bulging above the dorsal surface of CC on the midline. Clinical evaluations, CGH-array and instrumental analysis were also collected.
  
  
  RESULTS
  Among 85 patients with malformed CC, we identified 15 subjects that showed the supracallosal bundle. The CC was thickened in five cases, long and thinned in three cases, short and thinned in three cases and it had a "ribbon-like" appearance in four subjects. Additional brain anomalies were present in eight cases. DTI colour maps and tractography showed that the bundle had an antero-posterior longitudinal orientation and that the tract bifurcated posteriorly, ending in the posterior hippocampi. Patients had different combinations of neurological symptoms, but all showed mild or severe intellectual disability.
  
  
  CONCLUSIONS
  Combining radiological and genetic data with embryological knowledge of the development of cerebral commissures, we hypothesize that the supracallosal bundle represents a vestigial structure, the dorsal fornix, present during fetal life. Its persistence is associated with intellectual disability.
  
  
  CONCLUSIONS
  • An aberrant longitudinal bundle can be detected above corpus callosum. • The presence of the supracallosal bundle is associated with intellectual disability. • The supracallosal bundle may represent a persistent dorsal fornix.
authors.affiliation: Neuroimaging Laboratory, Scientific Institute IRCCS Eugenio Medea, Via don Luigi Monza 20, 23842, Bosisio Parini, Lecco, Italy. filippo.arrigoni@bp.lnf.it.
authors.forename: Filippo
authors.initials: F
authors.lastname: Arrigoni
authors.affiliation: Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
authors.forename: Romina
authors.initials: R
authors.lastname: Romaniello
authors.affiliation: Neuroimaging Laboratory, Scientific Institute IRCCS Eugenio Medea, Via don Luigi Monza 20, 23842, Bosisio Parini, Lecco, Italy.
authors.forename: Denis
authors.initials: D
authors.lastname: Peruzzo
authors.affiliation: Department of Pediatric Radiology and Neuroradiology, Children Hospital V. Buzzi, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Righini
authors.affiliation: Department of Pediatric Radiology and Neuroradiology, Children Hospital V. Buzzi, Milano, Italy.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Parazzini
authors.affiliation: Child Psychopathology Unit, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Colombo
authors.affiliation: Laboratory of Molecular Biology, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Bassi
authors.affiliation: Neuroradiology Department, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milano, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Triulzi
authors.affiliation: Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
authors.forename: Renato
authors.initials: R
authors.lastname: Borgatti
mesh_terms: D061085:Agenesis of Corpus Callosum / Q000175:diagnosis*; D003337:Corpus Callosum / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010641:Phenotype
keywords: Brain; Corpus callosum; Diffusion tensor imaging; Intellectual disability; Magnetic resonance imaging