title: Magnetoencephalographic analysis of periodic lateralized epileptiform discharges (PLEDs).
abstract: OBJECTIVE
  To clarify the spatial and temporal distribution of the electroencephalographic (EEG) pattern termed 'periodic lateralized epileptiform discharges' (PLEDs), we performed magnetoencephalography (MEG) to analyze PLEDs in a patient with a right parietal metastasis associated with meningeal carcinomatosis.
  
  
  METHODS
  A 37-channel biomagnetometer was used to simultaneously record the EEG and MEG. Equivalent current dipole (ECD) source localization was calculated based on a single-dipole model and mapped onto a magnetic resonance image. Single-photon emission computed tomography with technetium-99-hexamethyl-propyleneamine oxime (HMPAO-SPECT study) was also performed during both presence and absence of PLEDs according to an EEG monitor.
  
  
  RESULTS
  By EEG the PLEDs, predominantly right-sided, consisted of a typical negative triphasic spike followed by a slow negative wave. By MEG the PLEDs had a sequence with 3 distinct components. ECDs in the 3 components were localized to the cortex around the lesion, although exact localization and dipole direction varied between components. HMPAO-SPECT demonstrated hypoperfusion of the lesion and adjacent cortex during both quiescence and appearance of PLEDs.
  
  
  CONCLUSIONS
  Our results indicate that PLEDs originated from the hypoperfused cortex surrounding the lesion.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Graduate School of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hisada
authors.forename: T
authors.initials: T
authors.lastname: Morioka
authors.forename: S
authors.initials: S
authors.lastname: Nishio
authors.forename: M
authors.initials: M
authors.lastname: Muraishi
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Yoshida
authors.forename: M
authors.initials: M
authors.lastname: Fukui
mesh_terms: D001931:Brain Mapping; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D004827:Epilepsy / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000473:pathology; D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime