Longitudinal stability of interictal spikes in benign epilepsy with centrotemporal spikes

Abstract

Objective: To describe the natural history of electroencephalography (EEG) changes in patients with benign epilepsy with centrotemporal spikes (BECTS) over 1 year.

Methods: Centrotemporal spikes were visually evaluated based on 24-h ambulatory EEG studies to determine the total, left, right, and bilateral centrotemporal spikes patients were awake and asleep. These spike rates were then used to compare the entire night of sleep to the first 2 h of sleep, the repeatability of spike frequency over two recordings (done within days to weeks), and longitudinal changes in spike rate over 6 and 12 months.

Results: Nineteen children with newly diagnosed and untreated BECTS were included in this analysis. An excellent correlation was found between the centrotemporal spike rate during the entire duration of sleep and the first 2 h of sleep (intraclass correlation [ICC] 0.87, 95% confidence interval [CI] 0.67-0.95). In addition, an excellent correlation was found between two recordings completed an average of 23 days apart while patients were asleep (ICC 0.92, 95% CI 0.80-0.97) and good correlation while patients were awake (ICC 0.70, 95% CI 0.39-0.87). The average change in spike rate between recordings at baseline and at 6 months was a decrease of 64.7% (range -100% to +51.5%, p = 0.01) and the average change in rate between recordings at baseline and at 12 months was a decrease of 57.7% (range -100% to +29.1%, p = 0.01). In addition, within 6 months, most children had decreased centrotemporal rates, with 30% of children being spike-free. This absence of spikes did not continue in all children, since the majority (60%) had some spikes at 1 year following diagnosis.

Significance: Centrotemporal spike rates during sleep are stable when compared over days to weeks; however, when comparing spike rates over months there is a larger degree of variability.

Keywords: BECTS; Electroencephalography; Epilepsy.

Conflict of interest statement

Conflict of interest

We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

Figures

Figure 1

Comparison of spike rates between an entire night of sleep (24hr) and the first two hours of sleep (2hr). Ten children were included in this analysis and three of these children (1, 2, and 4) had multiple recordings which were analyzed. An excellent correlation was found between the CTS rate during the entire duration of sleep and the first 2 hours of sleep (ICC = 0.87, 95% CI = 0.67–0.95).

Figure 2

Comparison of spike rates between two recordings (Day 1 and Day 2) done an average of 23 days apart to determine the repeatability of spike frequency. CTS rates were compared while awake (top) and asleep (bottom) in seventeen children. An excellent correlation was found between the two recordings while asleep (ICC = 0.92, 95% CI = 0.80–0.97) and lower, but still very good correlation was found while awake (ICC = 0.70, 95% CI = 0.39–0.87).

Figure 3

Comparison of spike rates at baseline, 6 months, and 12 months in ten children. These are expressed as the percent change in CTS rate at 6 months and 12 months compared to baseline, so that a change of −100% indicates an absence of all spikes compared to baseline. The change in CTS rate was statistically significant when comparing baseline to 6 months (p=0.01) and baseline to 12 months (p=0.01) but not when comparing 6 months to 12 months (p=0.11).