title: White matter microstructural changes of thalamocortical networks in photosensitivity and idiopathic generalized epilepsy.
abstract: OBJECTIVE
  Photosensitivity or photoparoxysmal response (PPR) is an electroencephalography trait that is highly associated with idiopathic generalized epilepsies (IGEs) and characterized by changes in cortical excitability in response to photic stimulation. Studying functional and structural changes of PPR might provide important insights into the pathogenesis of IGE. Recent studies revealed a functional network consisting of occipital, parietal, and precentral areas that might be implicated in PPR. Herein, we investigate the microstructural changes associated with PPR.
  
  
  METHODS
  Twelve healthy subjects with PPR, nine patients with IGE and PPR (IGE-PPR group), and 18 healthy controls were studied with diffusion magnetic resonance imaging. Tract-based spatial statistics were used to test for regional differences in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity, and radial diffusivity between groups.
  
  
  RESULTS
  Subjects with PPR exhibited higher FA in the right precentral juxtacortical white matter and higher MD in lateral occipital areas relative to controls. Patients with IGE-patients showed additional increases in regional FA in the thalamus and juxtacortical precentral and parietal areas. Both subjects with PPR and patients with IGE-PPR presented axial and radial diffusivity changes in the occipital regions.
  
  
  CONCLUSIONS
  Our results show that PPR is associated with subcortical microstructural changes in precentral, parietal, and occipital regions. The coexistence of PPR and IGE is associated with white matter abnormalities in the thalamus and precuneus. PPR and epilepsy share similar functional and structural networks in widespread cortical and subcortical areas.
authors.affiliation: Department of Neurology, University Hospital Schleswig-Holstein, University of Kiel, Kiel, Germany. s.groppa@neurologie.uni-kiel.de
authors.forename: Sergiu
authors.initials: S
authors.lastname: Groppa
authors.forename: Friederike
authors.initials: F
authors.lastname: Moeller
authors.forename: Hartwig
authors.initials: H
authors.lastname: Siebner
authors.forename: Stephan
authors.initials: S
authors.lastname: Wolff
authors.forename: Christian
authors.initials: C
authors.lastname: Riedel
authors.forename: Günther
authors.initials: G
authors.lastname: Deuschl
authors.forename: Ulrich
authors.initials: U
authors.lastname: Stephani
authors.forename: Michael
authors.initials: M
authors.lastname: Siniatchkin
mesh_terms: D000293:Adolescent; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D004569:Electroencephalography; D004829:Epilepsy, Generalized / Q000209:etiology* / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009434:Neural Pathways / Q000473:pathology / Q000502:physiology; D010775:Photic Stimulation / Q000009:adverse effects*; D013788:Thalamus / Q000473:pathology*; D055815:Young Adult