Post-ictal Modulation of Baroreflex Sensitivity in Patients With Intractable Epilepsy

Abstract

Objective: Seizure-related autonomic dysregulation occurs in epilepsy patients and may contribute to Sudden Unexpected Death in Epilepsy (SUDEP). We tested how different types of seizures affect baroreflex sensitivity (BRS) and heart rate variability (HRV). We hypothesized that BRS and HRV would be reduced after bilateral convulsive seizures (BCS).Methods: We recorded blood pressure (BP), electrocardiogram (ECG) and oxygen saturation continuously in patients (n = 18) with intractable epilepsy undergoing video-EEG monitoring. A total of 23 seizures, either focal seizures (FS, n = 14) or BCS (n = 9), were analyzed from these patients. We used 5 different HRV measurements in both the time and frequency domains to study HRV in pre- and post-ictal states. We used the average frequency domain gain, computed as the average of the magnitude ratio between the systolic BP (BPsys) and the RR-interval time series, in the low-frequency (LF) band as frequency domain index of BRS in addition to the instantaneous slope between systolic BP and RR-interval satisfying spontaneous BRS criteria as a time domain index of BRS.Results: Overall, the post-ictal modulation of HRV varied across the subjects but not specifically by the type of seizures. Comparing pre- to post-ictal epochs, the LF power of BRS decreased in 8 of 9 seizures for patients with BCS; whereas following 12 of 14 FS, BRS increased. Similarly, spontaneous BRS decreased following 7 of 9 BCS. The presence or absence of oxygen desaturation was not consistent with the changes in BRS following seizures, and the HRV does not appear to be correlated with the BRS changes. These data suggest that a transient decrease in BRS and temporary loss of cardiovascular homeostatic control can follow BCS but is unlikely following FS.Significance: These findings indicate significant post-ictal autonomic dysregulation in patients with epilepsy following BCS. Further, reduced BRS following BCS, if confirmed in future studies on SUDEP cases, may indicate one quantifiable risk marker of SUDEP.

Blood Pressure in Seizures and Epilepsy

“…Indeed, the baroreflex sensitivity (BRS) was recently shown to be markedly impaired in the early postictal period following 7 FBTCS in 7 patients, whereas BRS was intact after 19 FS in 19 patients (78). These findings were largely replicated in a study by Esmaeili et al including 9 FBTCS and 14 FS of 18 patients (79). The apparent impairment of BRS in the aftermaths of FBTCS is possibly due to metabolically mediated muscular hyperemia in skeletal muscles following the generalized tonic-clonic convulsions (which overdrives neutrally-mediated sympathetic effects) on the one hand and the massive release of catecholamines with subsequent acceleration of HR on the other hand.…”

“…For instance, FBTCS are commonly followed by a postictal generalized electroencephalographic suppression (PGES) (81, 82) and in one patient, postictal hypotension was observed in association with PGES (68). Opposite to this assumption, however, postictal changes of BP and BRS were not related to occurrence or duration of PGES (70, 78, 79). Altogether, these results must be taken with caution and larger-scale studies are needed to confirm this hypothesis.…”

Risks and predictive biomarkers of sudden unexpected death in epilepsy patient

“…While BRS increased following 86% focal seizures, it significantly decreased in 89% of GTCS, suggesting a transient alteration of cardiovascular homeostatic control. 70 Another study explored BRS in 19 focal seizures and 7 GTCS and confirmed these findings with a major BRS drop following GTCS (from 15 to 3.1 ms/mm Hg) but not after focal seizures. 69 Intracerebral electrical stimulation performed in 12 patients undergoing invasive EEG recordings showed that stimulation of Broadman area 25 was selectively associated with striking systolic hypotensive changes.…”

“…68 Two recent studies have investigated the baroreflex sensitivity (BRS) in patients with epilepsy. 69,70 The first study investigated 14 focal seizures and nine GTCS. While BRS increased following 86% focal seizures, it significantly decreased in 89% of GTCS, suggesting a transient alteration of cardiovascular homeostatic control.…”

Heart Rate Variability Parameters During Psychogenic Non-epileptic Seizures: Comparison Between Patients With Pure PNES and Comorbid Epilepsy

“…While several studies have investigated interictal autonomic nervous system (ANS) changes in epilepsy (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) and PNES (22)(23)(24)(25)(26), no information is yet available about putative differences in ANS activity alterations induced by pPNES as compared to PNES/ES. In this context, a sympathetic overdrive higher than that observed during PNES was described in temporal lobe seizures (24,27).…”