J Clin Neurol.  2006 Sep;2(3):179-185. 10.3988/jcn.2006.2.3.179.

Classification and Serial Evolution of PLEDs

• Kim YS
• Choi SY
• Kwag HJ
• Kim JM

• KMID: 2287691
• DOI: http://doi.org/10.3988/jcn.2006.2.3.179

Abstract

BACKGROUND AND PURPOSE
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.

Keyword

PLEDs; EEG; Classification; Prognosis

MeSH Terms

Brain
Classification*
Electroencephalography
Humans
Prognosis

Figure

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  Figure 1 Representative EEG recordings showing diverse patterns of PLEDs proper of class 3: (A) simple, (B) benign, (C) vigorous, and (D) suppressed.

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  Figure 2 Average evolution of five patients with initial vigorous PLEDs proper of class 3. The X-axis represents the sequence of EEG recordings and the Y-axis represents the EEG findings: 1; slowing, 2; occasional sharp, 3; frequent sharp, 4; PLEDs proper of class 1, 5; PLEDs proper of class 2, 6; simple PLEDs proper of class 3, 7; benign PLEDs proper of class 3, 8; vigorous PLEDs proper of class 3, 9; suppressed PLEDs proper of class 3, 10; PLEDs plus of class 4, and 11; PLEDs plus of class 5.

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  Figure 3 Average evolution of two patients with initial suppressed PLEDs proper of class 3 (axes as in Fig. 2).

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  Figure 4 Stepwise evolution of PLEDs (axes as in Fig. 2).

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  Figure 5 Relationship between PLEDs classification and functional status at follow-up: (A) benign group comprising PLEDs proper of classes 1 and 2, and simple or benign PLEDs proper of class 3 (n=25), and (B) malignant group comprising vigorous or suppressed PLEDs proper of class 3, and PLEDs plus of class or 5 (n=17).

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  Figure 6 Resolution of PLEDs during the follow-up EEGs: (A) benign group and (B) malignant group. f/u; follow-up.

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  Figure 7 EEG seizure and functional status at follow-up: (A) with EEG seizure (n=7) and (B) without EEG seizure (n=30).

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