title: Neuroimaging and neurophysiology of periodic lateralized epileptiform discharges: observations and hypotheses.
abstract: OBJECTIVE
  We assessed neuroimaging lesion type and distribution in patients with periodic lateralized epileptiform discharges (PLEDs), with a view to identifying electrographic differences between PLEDs associated with differing lesion locations. Our observations led us to consider a conceptual synthesis between PLEDs and periodic complexes (PCs).
  
  
  METHODS
  Retrospective review of acute neuroimaging results (CT/MRI) on patients identified to have EEG PLEDs, for the period 1999-2003 (n=106). Blinded classification of original EEG recordings.
  
  
  RESULTS
  Neuroimaging abnormalities were classified as acute or chronic cortical, or acute or chronic subcortical. Seven out of 106 scans were classified nonlesional. Overall approximately 70% of scans had cortical abnormalities, whether acute or chronic; approximately 23% had subcortical abnormalities. "Cortical" PLEDs were significantly longer in duration (p<0.05) and more variable in morphology (p<0.01) than "subcortical" PLEDs.
  
  
  CONCLUSIONS
  Structural brain disease commonly, but not invariably, underlies PLEDs; lesion type is spatiotemporally variable. Cortical and subcortical PLEDs have distinct EEG signatures. There is evidence that these may relate to mechanisms for other pathological large-scale oscillatory brain synchronies (e.g., PCs).
authors: Section of Epilepsy, Department of Neurology, Cleveland Clinic, Cleveland, Ohio, USA. Giridhar.P.Kalamangalam@uth.tmc.edu
authors: Giridhar P
authors: GP
authors: Kalamangalam
authors: Beate
authors: B
authors: Diehl
authors: Richard C
authors: RC
authors: Burgess
mesh_terms: D001479:Basal Ganglia / Q000473:pathology / Q000503:physiopathology; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D001927:Brain Diseases / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D038524:Diffusion Magnetic Resonance Imaging; D004569:Electroencephalography / Q000145:classification / Q000706:statistics & numerical data*; D004827:Epilepsy / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D012189:Retrospective Studies; D013788:Thalamus / Q000473:pathology / Q000503:physiopathology; D014057:Tomography, X-Ray Computed