The relationship between the interictal parameters of cardiovascular autonomic regulation and the outcomes of surgical treatment of epilepsy

Objective. The purpose of our study was to test the hypothesis of more severe preoperative autonomic dysfunction among patients who did not achieve complete control of seizures after neurosurgical treatment. Material and methods. For patients with drug-resistant focal epilepsy undergoing preoperative examination, heart rate (RR intervals, RRIs), systolic blood pressure for each heartbeat (BPsys), and respiratory rate were recorded for 5 minutes of lying down, 3 minutes of metronomic breathing, and 5 minutes of active orthostatic testing. Heart rate variability parameters in the time (SDNN, CV-RRI, RMSSD) and spectral (LF-RRI, HF-RRI, TP-RRI, LF/HF-RRI) domains, low-frequency BPsys variability (LF-BPsys), arterial baroreflex sensitivity (BRS), and expiration/inspiration and 30:15 indices were analyzed. Preoperative parameters of patients with seizures (Engel Ib-IV) and those without seizures (Engel Ia) were compared with those of healthy subjects after 12 months. Results. When compared with a control (n=46, age 31 [27; 37] years, 17 males), patients with both no seizures (n=20, age 35 [25; 43] years, 8 males) and persistent seizures (n=21, age 37 [29; 44] years, 4 males) showed reduced values of SDNN, CV-RRI, TP-RRI, LF-RRI, BRS at rest, and the 30:15 index. Only patients with persistent seizures had elevated LF-BPsys in the orthostatic position (23.4 [16.2; 58.5] vs 14.4 [9.9; 23.9] mmHg2, p<0.005) and abnormal low BRS at rest in 28.6% of cases (p=0.012), indicating baroreflex dysfunction. Conclusion. Baroreflex dysfunction may be associated with a lower probability of achieving seizure remission after surgical treatment of epilepsy.