title: Classification and Serial Evolution of PLEDs.
abstract: OBJECTIVE
  Periodic lateralized epileptiform discharges (PLEDs) are defined as spikes or sharp waves occurring at an approximately regular interval. PLEDs are subdivided into PLEDs proper and PLEDs plus in Reiher's classification, but since this does not sufficiently reflect the pleomorphism of PLEDs, we propose a new subclassification scheme of PLEDs, and discuss the relationship between them and clinical prognoses.
  
  
  METHODS
  Thirty-seven patients who had at least two available EEGs were included in this study. Each patient had structural brain lesions identified in brain CT/MRI: 237 EEGs from 37 patients were reviewed and the patterns of PLEDs were classified by electroencephalographic characteristics based on Reiher's classification. PLEDs proper of class 3 were subclassified into four categories: (1) simple, (2) benign, (3) vigorous, and (4) suppressed.
  
  
  RESULTS
  Most of the PLEDs that started with the vigorous or suppressed pattern of class 3 evolved into the simple or benign pattern of class 3 and subsequently changed into class 1 or class 2, finally intermingling with the neighboring background waves. PLEDs that started with the benign or simple pattern of class 3 rapidly changed into class 1 or 2. Patients showing the benign or simple pattern of class 3 exhibited a better clinical prognosis.
  
  
  CONCLUSIONS
  PLEDs have five distinctive classes, and over time they evolve from malignant PLEDs plus to benign PLEDs proper before finally disappearing. It appears that those of class 3 have more diverse patterns, with the vigorous and suppressed patterns being the more malignant forms of PLEDs in this class.
authors.affiliation: Department of Neurology, Chungnam National University College of Medicine, Daejeon, Korea.
authors.forename: Ye-Sung
authors.initials: YS
authors.lastname: Kim
authors.forename: Soo-Young
authors.initials: SY
authors.lastname: Choi
authors.forename: Hyun-Jeong
authors.initials: HJ
authors.lastname: Kwag
authors.forename: Jae-Moon
authors.initials: JM
authors.lastname: Kim
references.citation: J Clin Neurophysiol. 2002 Apr;19(2):172-7
references.pmid: 11997729
references.citation: J Clin Neurophysiol. 2005 Apr;22(2):79-91
references.pmid: 15805807
references.citation: J Clin Neurophysiol. 1989 Apr;6(2):159-72
references.pmid: 2708516
references.citation: J Clin Neurophysiol. 1996 Nov;13(6):519-30
references.pmid: 8978624
references.citation: Electroencephalogr Clin Neurophysiol. 1991 Jan;78(1):12-7
references.pmid: 1701709
references.citation: Arch Neurol. 1980 Jan;37(1):15-20
references.pmid: 6766064
references.citation: Epilepsia. 2004 Feb;45(2):109-23
references.pmid: 14738418
references.citation: J Clin Neurophysiol. 1990 Apr;7(2):249-67
references.pmid: 2187023
references.citation: Epilepsy Res. 1990 Jan-Feb;5(1):49-60
references.pmid: 2303022
references.citation: Arch Neurol. 2002 Feb;59(2):195-201
references.pmid: 11843689
references.citation: Electroencephalogr Clin Neurophysiol. 1964 Aug;17:177-93
references.pmid: 14204927
references.citation: Epilepsia. 1987 Sep-Oct;28(5):533-6
references.pmid: 3653057
references.citation: Seizure. 2000 Sep;9(6):402-6
references.pmid: 10985996