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Slower alpha rhythm associates with poorer seizure control in epilepsy

Research output: Contribution to journalArticle

Original languageEnglish
JournalAnnals of Clinical and Translational Neurology
Publication statusAccepted/In press - 26 Nov 2018

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Abstract

Objective: Slowing and frontal spread of the alpha rhythm have been reported in multiple epilepsy syndromes. We investigated whether these phenomena are associated with seizure control.
Methods: We prospectively acquired resting-state EEG in 63 patients with focal and idiopathic generalized epilepsy (FE and IGE) and 39 age- and gender-matched healthy subjects. Patients were divided into good and poor (≥ 4 seizures / 12 months) seizure control groups based on self-reports and clinical records. We computed spectral power from 20-second EEG segments during eyes-closed wakefulness, free of interictal abnormalities, and quantified power in high and low alpha bands. Analysis of covariance and post-hoc t-tests were used to assess group differences in alpha-power shiftacross all EEG channels. Permutation-based statistics were used to assess the topography of this shift across the whole
scalp.
Results: Compared to healthy subjects, patients showed a statistically significant shift of spectral power from high- to low-alpha frequencies (effect size g = 0.78 [95% confidence interval 0.43,1.20]). This alpha-power shift was driven by
patients with poor seizure control in both FE and IGE (g = 1.14, [0.65,1.74]), and occurred over midline frontal and bilateral occipital regions. IGE exhibited less alpha power shift compared to FE over bilateral frontal regions (g = -1.16
[-0.68, -1.74]). There was no interaction between syndrome and seizure control. Effects were independent of antiepileptic drug load, time of day, or subgroup definitions.
Interpretation: Alpha slowing and anteriorisation are a robust finding in patients with epilepsy and might represent a
generic indicator of seizure liability.

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