Respiratory Arousal Threshold in Patients with Epilepsy and Obstructive Sleep Apnea.

Background: Patients with epilepsy (PWE) have a higher likelihood of developing obstructive sleep apnea (OSA). However, limited literature investigates the phenotypes of OSA in this population. This study aimed to evaluate the respiratory arousal threshold (rAT) in PWE with concurrent OSA.

Methods: Patients were recruited from the Sleep and Epilepsy Center at Chang Gung Memorial Hospital between January 2010 and June 2022. We included adult patients who underwent overnight in-laboratory polysomnography after the onset of epilepsy. Additionally, age-, sex-, and apnea-hypopnea index (AHI)-matched patients with OSA only were included as controls. Low rAT was defined using predictive models based on polysomnography criteria.

Results: We enrolled 48 PWE, of whom 36 (75%) had concurrent OSA (PWE+OSA), and 108 patients with OSA only. PWE+OSA were older upon PSG examination and had a later epilepsy onset compared to PWE only. PWE had more concomitant antiseizure medications and hypnotics compared to patients with OSA only. Among those with OSA, 19 (52.8%) with PWE+OSA and 68 (63.0%) with OSA only were predicted to have a low rAT. Continuous positive airway pressure compliance was significantly lower in the low rAT subgroup compared to the high rAT subgroup (p = 0.021) within the OSA-only group, whereas no significant difference was observed between rAT subgroups in the PWE+OSA group.

Conclusion: Our study provides insights into the presence of a low rAT in PWE+OSA, with no significant difference in its ratio compared to OSA controls. However, since rAT was estimated using a predictive model rather than direct measurement, this limitation may affect the interpretation of our findings. Further studies using gold-standard methods are needed to clarify the underlying mechanisms contributing to the higher OSA prevalence in PWE.