The stability of spike counts in children with interictal epileptiform activity
Mark H Libenson1, Amit Haldar1, Anna L Pinto1
1Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA.
Insights
Spike counts in children undergoing ambulatory EEG show significant natural variation between consecutive nights. This variability suggests that spike frequency may fluctuate considerably over time, impacting diagnostic interpretations.
Area of Science:
- Pediatric Neurology
- Clinical Neurophysiology
Background:
- Epileptiform spike activity in children is often monitored using electroencephalography (EEG).
- The stability of serial spike count measurements in pediatric populations is not well-established.
- Understanding spike count variability is crucial for accurate interpretation of EEG findings.
Purpose of the Study:
- To investigate the stability of serial spike counts in children.
- To determine the extent of variation in spike frequency between consecutive nights of ambulatory EEG recordings.
Main Methods:
- Analysis of 40 consecutive 48-hour ambulatory EEGs in children with spikes but no seizures.
- Visual counting of spikes in the first 20 minutes after the first sleep spindle during nighttime sleep.
- Comparison of spike counts between the first and second nights of recording.
Main Results:
- Fifty-five unique spike foci were analyzed in 40 children (age range: 9 months to 19 years).
- Significant variation in spike frequency was observed between Night 1 and Night 2 (mean change: 42.1%, median: 28.3%).
- The coefficient of variation was 0.94, indicating substantial variability; 25.1% of spike foci varied by 50% or more.
Conclusions:
- Consecutive night-to-night spike counts in children exhibit significant natural variability.
- This variability implies that spike frequency is not a stable measure over short intervals.
- Longer intervals between spike counts may reveal even greater fluctuations, necessitating careful consideration in clinical practice.
Purpose:
Little is known about the stability of serial measures of spike counts in children or whether spike counts are an inherently stable or unstable measure. We investigated the variation in first- and second-night spike counts in children undergoing 48-h ambulatory EEG recording.
Methods:
We analyzed 40 consecutive 48-h ambulatory EEGs performed at Boston Children's Hospital that manifested spikes but no seizures. Distinct spike foci in the same child were counted separately. We visually counted all spikes in the first 20min after the first sleep spindle during nighttime sleep, comparing the first and second nights.
Results:
Fifty-five unique spike foci were counted in 40 children (age range: 9 months to 19 years; median: 8.4 years). Considerable variation was seen when comparing Night 1 and Night 2 spike counts: for all foci, Night 1 mean and median spike counts were 304.5 and 126 and Night 2 counts were 309.5 and 148, respectively. For each focus, the mean change in spike frequency between Night 1 and Night 2 was 42.1% (median=28.3%, IQR 19.0-50.0%). The coefficient of variation of 0.94 suggested a large amount of variation. The percentage change weighted according to high or low spike frequency was 25.1%.
Conclusion:
In 40 children with 55 unique spike foci, significant variability in spike frequency was seen between consecutive nights of sleep, suggesting significant natural variation in spike frequency. A quarter of spike foci varied by 50% or more. Spike counts separated by longer intervals may show even more dramatic natural variation.
Related Concept Videos
01:22Epilepsy ll: Types
01:13Seizures: Classification
Seizures are typically classified into two main categories: focal and generalized seizures.
Focal Seizures
Focal seizures originate from specific regions of the brain. These seizures are further sub-classified into two types: