Bimodal ultradian seizure periodicity in human mesial temporal lobe epilepsy
Matthew Karafin1, Erik K St Louis, M Bridget Zimmerman
1Iowa Comprehensive Epilepsy Program, Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, United States.
Background:
Mesial temporal lobe epilepsy (mTLE) has been suggested to follow a circadian rhythm. Previous research found an afternoon peak in mTLE seizure occurrence. We evaluated the pattern of seizure occurrence in patients with well-localized mTLE and hypothesized that peak seizure frequency would occur in the afternoon, and that this pattern would not be altered by age, gender, or seizure focus.
Methods:
We retrospectively identified consecutive mTLE patients with a seizure-free outcome following anterior temporal lobectomy from 1993 to 2004 with video-EEG captured seizures. We recorded and plotted the 24-h clock time for each seizure and performed cosinor analysis. SAS Proc GLIMMIX was used to fit the linearized transform of the cosinor model. Negative binomial regression fitted by the generalized estimating equations (GEE) method was also performed to estimate and compare the mean seizure rates over a 24-h day.
Results:
Sixty mTLE patients monitored between 2 and 16 days were analyzed. Mean (standard deviation), median number of seizures per subject were 10.47(7.86), 9.00. Cosinor plots indicated that the function had two modes: 7-8 a.m. and 4-5 p.m. GEE analysis was consistent with peak seizure frequency occurrence at 6-8 a.m. (p<0.0001) and 3-5 p.m. (p<0.01).
Conclusions:
We found a bimodal pattern of seizure occurrence in human mTLE, with peak seizure frequencies occurring between 6-8 a.m. and 3-5 p.m. confirming an afternoon peak, as well as a previously unsuspected morning peak in seizure occurrence that provides rationale for future investigations of antiepileptic drug chronopharmacology and informs patient counseling regarding patterns of seizure occurrence.
Insights
Mesial temporal lobe epilepsy (mTLE) seizures show a bimodal pattern, peaking in the early morning (6-8 a.m.) and late afternoon (3-5 p.m.). This finding supports circadian rhythm influences on mTLE seizure occurrence.
Area of Science:
- Neurology
- Epilepsy Research
- Chronobiology
Background:
- Mesial temporal lobe epilepsy (mTLE) is suspected to exhibit circadian rhythmicity.
- Prior studies indicated an afternoon peak for mTLE seizure occurrence.
- This study investigated seizure patterns in patients with well-localized mTLE.
Purpose of the Study:
- To evaluate the temporal pattern of seizure occurrence in patients with well-localized mTLE.
- To test the hypothesis of an afternoon peak in seizure frequency.
- To determine if age, gender, or seizure focus alter this pattern.
Main Methods:
- Retrospective analysis of 60 mTLE patients with video-EEG confirmed seizures post-anterior temporal lobectomy.
- Cosinor analysis and SAS Proc GLIMMIX to model seizure timing.
- Generalized estimating equations (GEE) to compare mean seizure rates over 24 hours.
Main Results:
- Analysis of 60 mTLE patients revealed a bimodal seizure pattern.
- Cosinor plots showed seizure peaks between 7-8 a.m. and 4-5 p.m.
- GEE analysis confirmed peak seizure frequencies from 6-8 a.m. (p<0.0001) and 3-5 p.m. (p<0.01).
Conclusions:
- Human mTLE exhibits a bimodal seizure occurrence pattern.
- Confirmed afternoon peak and identified a novel morning peak (6-8 a.m.).
- Findings support further research into antiepileptic drug chronopharmacology and patient counseling.
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: