Paroxysmal cortical slowing linked to drug-resistant epilepsy

Area of Science:

• Neuroscience
• Clinical Neurology
• Biomarker Discovery

Background:

• Paroxysmal slow wave events (PSWEs) are EEG segments with median power frequency below 6 Hz for ≥5 seconds.
• PSWEs have previously shown predictive value for epilepsy in patients experiencing their first seizure.
• This study investigates the prevalence, localization, and potential of PSWEs as biomarkers for drug-resistant epilepsy (DRE).

Purpose of the Study:

• To evaluate the prevalence and localization of PSWEs in large, independent EEG datasets.
• To explore the utility of PSWEs as potential biomarkers for identifying drug-resistant epilepsy (DRE).
• To assess the association between PSWEs and epilepsy aetiology, localization, and treatment response.

Main Methods:

• An exploratory analysis involved 1064 participants from the Temple University EEG corpus, comparing epilepsy patients with controls.
• A validation analysis used an independent cohort of 95 participants from Bonn University, including drug-responsive epilepsy and DRE patients.
• EEG data was analyzed to quantify the proportion of time spent in PSWEs and their localization.

Main Results:

• PSWEs were significantly more prolonged in patients with epilepsy compared to those without (P < 0.0001).
• Prolonged PSWEs were most prominent in focal epilepsy, especially with temporal lobe involvement (P = 0.005).
• Patients with DRE exhibited prolonged PSWEs, correlating with an increased risk of refractoriness (OR = 1.9) and confirmed in validation (AUC = 0.829).
• Pre-surgical EEGs in patients with poor surgical outcomes (Engel IB-IV) showed prolonged PSWEs compared to successful outcomes (Engel IA).

Conclusions:

• Analysis of 1159 EEGs across two cohorts confirms PSWEs are more prevalent and prolonged in focal epilepsy.
• Prolonged PSWEs may serve as a predictive biomarker for drug-resistant epilepsy (DRE).
• PSWEs could indicate a lack of therapeutic response in epilepsy patients.