title: Cerebral Reorganization after Hemispherectomy: A DTI Study.
abstract: Hemispherectomy is a neurosurgical procedure to treat children with intractable seizures. Postsurgical improvement of cognitive and behavioral functions is observed in children after hemispherectomy suggesting plastic reorganization of the brain. Our aim was to characterize changes in DTI scalars in WM tracts of the remaining hemisphere in children after hemispherectomy, assess the associations between WM DTI scalars and age at the operation and time since the operation, and evaluate the changes in GM fractional anisotropy values in patients compared with controls.
  
  
  
  Patients with congenital or acquired neurologic diseases who required hemispherectomy and had high-quality postsurgical DTI data available were included in this study. Atlas- and voxel-based analyses of DTI raw data of the remaining hemisphere were performed. Fractional anisotropy and mean, axial, and radial diffusivity values were calculated for WM and GM regions. A linear regression model was used for correlation between DTI scalars and age at and time since the operation.
  
  
  
  Nineteen patients after hemispherectomy and 21 controls were included. In patients, a decrease in fractional anisotropy and axial diffusivity values and an increase in mean diffusivity and radial diffusivity values of WM regions were observed compared with controls (P < .05, corrected for multiple comparisons). In patients with acquired pathologies, time since the operation had a significant positive correlation with white matter fractional anisotropy values. In all patients, an increase in cortical GM fractional anisotropy values was found compared with controls (P < .05).
  
  
  
  Changes in DTI metrics likely reflect Wallerian and/or transneuronal degeneration of the WM tracts within the remaining hemisphere. In patients with acquired pathologies, postsurgical fractional anisotropy values correlated positively with elapsed time since the operation, suggesting a higher ability to recover compared with patients with congenital pathologies leading to hemispherectomy.
authors.affiliation: From the Section of Pediatric Neuroradiology (A.M., T.A.G.M.H., A.P.).
authors.forename: A
authors.identifier: 0000-0002-4192-722X
authors.initials: A
authors.lastname: Meoded
authors.affiliation: Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Sciences (A.V.F., S.M.).
authors.forename: A V
authors.identifier: 0000-0002-1673-002X
authors.initials: AV
authors.lastname: Faria
authors.affiliation: Departments of Neurology (A.L.H., M.V.J.).
authors.forename: A L
authors.identifier: 0000-0001-5672-3409
authors.initials: AL
authors.lastname: Hartman
authors.affiliation: Neurosurgery (G.I.J.), The Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: G I
authors.identifier: 0000-0001-9607-6867
authors.initials: GI
authors.lastname: Jallo
authors.affiliation: Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Sciences (A.V.F., S.M.) F.M. Kirby Research Center for Functional Brain Imaging (S.M.).
authors.forename: S
authors.identifier: 0000-0001-8104-0327
authors.initials: S
authors.lastname: Mori
authors.affiliation: Departments of Neurology (A.L.H., M.V.J.) Kennedy Krieger Institute (M.V.J.), Baltimore, Maryland.
authors.forename: M V
authors.identifier: 0000-0002-3701-6028
authors.initials: MV
authors.lastname: Johnston
authors.affiliation: From the Section of Pediatric Neuroradiology (A.M., T.A.G.M.H., A.P.).
authors.forename: T A G M
authors.identifier: 0000-0003-2302-6724
authors.initials: TA
authors.lastname: Huisman
authors.affiliation: From the Section of Pediatric Neuroradiology (A.M., T.A.G.M.H., A.P.) aporett1@jhmi.edu.
authors.forename: A
authors.identifier: 0000-0002-9594-3858
authors.initials: A
authors.lastname: Poretti
mesh_terms: D016880:Anisotropy; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D002648:Child; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D038421:Hemispherectomy; D006801:Humans; D016014:Linear Models; D008297:Male; D009410:Nerve Degeneration / Q000000981:diagnostic imaging* / Q000473:pathology; D066127:White Matter / Q000000981:diagnostic imaging* / Q000473:pathology