Abstracts

Rationale: Patent foramen ovale (PFO) can cause dysfunction of cerebral vascular endothelial cells, changes in cortical excitability or trigger cortical spreading depression by inducing ischemia/hypoxia, which predisposes patients to conditions such as stroke and migraine. Epilepsy is often comorbid with migraine, and they overlap in many clinical features, treatment options, and common pathogenic mechanisms. In fact, we had previously found that PFO was more common in patients with epilepsy (PWEs) than in the general population and could be an independent risk factor of drug resistance according to the arterial blood gas assessment. Furthermore, in 2024, our team reported that PFO closure can result in a reduction in the frequency and severity of seizures. However, little is known about brain functional changes caused by PFO closure. This study aimed to investigate the influence of PFO closure on the internal mode of brain functional connectivity (FC) in PWEs and perform correlation analysis among preoperative FC and postoperative efficacy.

Methods: The study was approved by the Medical Ethics Committee of West China Hospital of Sichuan University. The fMRI scans were performed in 13 PWEs who underwent PFO closure. All patients participated in identical fMRI scanning sessions at one day before operation and six, twelve months after operation. There were no changes in the types or dosages of antiepileptic drugs during the time between preoperative and postoperative scan. Independent component analysis was conducted to identify brain networks. The dual regression method and FSLNets package were used to detect group differences in FC within and inter networks and explore their correlation with postoperative seizure reduction.

Results: Of the 13 epilepsy patients who confirmed PFO observed, average age of surgery was 25.92 years, and 5 cases were female (38.46%). At the end of postoperative follow-up, there was no residual partial flow, and the overall attack frequency (P < 0.001) and severity (P = 0.004) decreased significantly. The results showed that the impact of PFO closure manifested in the rsFC among the visual, default mode, dorsal attention and salience networks. After the linear mixed-model, we found that the FC between these networks had a strong correlation with the remission degree of postoperative frequency.