title: Microstructure of transcallosal motor fibers reflects type of cortical (re-)organization in congenital hemiparesis.
abstract: BACKGROUND
  Early unilateral brain lesions can lead to different types of corticospinal (re-)organization of motor networks. In one group of patients, the contralesional hemisphere exerts motor control not only over the contralateral non-paretic hand but also over the (ipsilateral) paretic hand, as the primary motor cortex is (re-)organized in the contralesional hemisphere. Another group of patients with early unilateral lesions shows "normal" contralateral motor projections starting in the lesioned hemisphere.
  
  
  OBJECTIVE
  We investigated how these different patterns of cortical (re-)organization affect interhemispheric transcallosal connectivity in patients with congenital hemiparesis.
  
  
  METHODS
  Eight patients with ipsilateral motor projections (group IPSI) versus 7 patients with contralateral motor projections (group CONTRA) underwent magnetic resonance diffusion tensor imaging (DTI). The corpus callosum (CC) was subdivided in 5 areas (I-V) in the mid-sagittal slice and volumetric information. The following diffusion parameters were calculated: fractional anisotropy (FA), trace, radial diffusivity (RD), and axial diffusivity (AD).
  
  
  RESULTS
  DTI revealed significantly lower FA, increased trace and RD for group IPSI compared to group CONTRA in area III of the corpus callosum, where transcallosal motor fibers cross the CC. In the directly neighboring area IV, where transcallosal somatosensory fibers cross the CC, no differences were found for these DTI parameters between IPSI and CONTRA. Volume of callosal subsections showed significant differences for area II (connecting premotor cortices) and III, where group IPSI had lower volume.
  
  
  CONCLUSIONS
  The results of this study demonstrate that the callosal microstructure in patients with congenital hemiparesis reflects the type of cortical (re-)organization. Early lesions disrupting corticospinal motor projections to the paretic hand consecutively affect the development or maintenance of transcallosal motor fibers.
authors.affiliation: Department of Pediatrics, Klinikum rechts der Isar, Technical University Munich, Koelner Platz 1, 80804 Munich, Germany; Department of Pediatric Neurology and Developmental Medicine, University Children's Hospital, Tübingen, Germany. Electronic address: hendrik.juenger@lrz.tu-muenchen.de.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Juenger
authors.affiliation: Psychiatry Neuroimaging Laboratory, Department of Radiology and Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, USA; Institute for Clinical Radiology, Ludwig-Maximilian-University, Munich, Germany; Department of Child and Adolescent Psychiatry, Psychosomatic and Psychotherapy, Ludwig-Maximilian-University, Munich, Germany.
authors.forename: Inga K
authors.initials: IK
authors.lastname: Koerte
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilian-University, Munich, Germany; Psychiatry Neuroimaging Laboratory, Department of Radiology and Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, USA; Department of Child and Adolescent Psychiatry, Psychosomatic and Psychotherapy, Ludwig-Maximilian-University, Munich, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Muehlmann
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilian-University, Munich, Germany; Psychiatry Neuroimaging Laboratory, Department of Radiology and Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Mayinger
authors.affiliation: Social Pediatrics and Developmental Medicine, Klinikum rechts der Isar, Technical University Munich, Koelner Platz 1, 80804 Munich, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Mall
authors.affiliation: Department of Pediatric Neurology and Developmental Medicine, University Children's Hospital, Tübingen, Germany.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Krägeloh-Mann
authors.affiliation: Psychiatry Neuroimaging Laboratory, Department of Radiology and Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, USA; Veterans Affairs (VA) Boston Healthcare System, Brockton, MA, USA.
authors.forename: Martha E
authors.initials: ME
authors.lastname: Shenton
authors.affiliation: Clinic for Neuropediatrics and Neurorehabilitation, Epilepsy Center for Children and Adolescents, Krankenhausstr. 20, 83569 Vogtareuth, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Berweck
authors.affiliation: Department of Pediatric Neurology and Developmental Medicine, University Children's Hospital, Tübingen, Germany; Clinic for Neuropediatrics and Neurorehabilitation, Epilepsy Center for Children and Adolescents, Krankenhausstr. 20, 83569 Vogtareuth, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Staudt
authors.affiliation: Department of Pediatric Neurology and Developmental Medicine, Hauner Children's Hospital, Ludwig-Maximilian-University, Munich, Germany; German Center for Vertigo and Balance Disorders, University of Munich, Munich, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Heinen
mesh_terms: D000293:Adolescent; D000328:Adult; D016880:Anisotropy; D001931:Brain Mapping; D002648:Child; D003337:Corpus Callosum / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000473:pathology*; D010291:Paresis / Q000151:congenital* / Q000473:pathology*; D011712:Pyramidal Tracts / Q000473:pathology; D018709:Statistics, Nonparametric; D055815:Young Adult
keywords: Congenital hemiparesis; Corpus callosum; Diffusion tensor imaging