Paroxysmal slow wave events as a diagnostic biomarker for epilepsy: Lessons from rural Zambia

Objective: Epilepsy affects more than 50 million people globally, with low- and middle-income countries (LMICs) bearing the greatest burden due to limited medical resources and stigma. Electroencephalography (EEG) is a cost-effective diagnostic tool, but its interpretation often requires unavailable expertise in rural areas. There is a pressing need for reliable, quantitative EEG biomarkers to enhance diagnosis, guide imaging, and monitor treatment. Methods: We investigated paroxysmal slow wave events (PSWEs), transient markers of cortical network slowing, in scalp EEG recordings from epilepsy patients at the Kakumbi Rural Health Center in Zambia (n = 127) and from Bonn Epilepsy Center (n = 132). PSWE characteristics, including occurrence, duration, and spatial distribution, were analyzed. Source localization of PSWEs was performed using standardized low-resolution brain electromagnetic tomography software. Results: PSWEs were observed in all patients with epilepsy. Time in PSWE showed negative correlation with patient age (r = −.26, p =.003) and disease onset (r = −.25, p =.005), regardless of age. PSWE characteristics, including temporal and spatial distribution, were associated with disease severity and similar to drug-resistant patients from Bonn Epilepsy Center. EEGs reported as “abnormal” had greater time in PSWE compared with “normal” EEGs (p =.024). Focal PSWE source localization suggested the presence of an intracranial lesion on computed tomography (area under the curve =.7). Significance: This study supports previous research on the potential of PSWEs as a quantitative EEG biomarker in epilepsy. Automated analysis of PSWEs can enhance diagnostic accuracy and assist in screening patients for brain imaging, particularly in resource-constrained settings. This approach offers a practical solution to bridge the diagnostic gap in LMICs that can potentially be used to improve epilepsy management and patient outcomes.