Abstracts

Rationale: Epilepsy carries a mortality rate two to three times that of the general population. The commonest seizure related death is sudden unexpected death in epilepsy (SUDEP). The mechanism of SUDEP is unknown. Evidence suggests abnormalities of autonomic control.Methods: We examined heart rate variability (HRV) & baroreflex sensitivity (BRS) in active epilepsy along with age & sex matched controls. Active epilepsy was defined as a seizure in the last 5 years. All seizure syndromes were included. Patients with a co-existing condition or medication that may alter autonomic function were excluded. HRV was measured in time & frequency domains. BRS was measured via a finometer and BeatScope software. 50 patients were recruited. 8 were excluded. 42 patients underwent final analysis for time domain HRV and BRS. Frequency domain analysis was carried out on 36. Results: Statistical analysis was carried out with SSPS v19. HRV in the time domain was not significantly different (p>0.05). HRV in the frequency domain and BRS were significantly lower in the epilepsy patients compared to controls. Low & high frequency values were reduced in the cases compared to controls (p=0.041 & p=0.05 respectively). BRS in the epilepsy group was also significantly lower than the control group (p=0.015). No correlation was found between HRV, BRS and epilepsy syndrome, duration of epilepsy, seizure frequency, nocturnal seizures or anti-convulsant medication. Conclusions: Both HRV and BRS are measures of autonomic function. Reductions in these parameters are indicative of autonomic dysfunction and predict mortality following a myocardial infarction (MI) (1). Impaired autonomic function is well described in chronic epilepsy and this has led to suggestions that it plays a potential role in SUDEP (2) (3). Our work has added to the literature on HRV in epilepsy which almost certainly to some extent is involved in SUDEP. There has been little work on BRS in epilepsy to date with one case-control study in the literature at the time of writing (4). BRS was reduced in the epilepsy group compared to controls. We also studied a larger patient group than previous work by Dutsch et al.(4). Given that impaired HRV and BRS predict cardiovascular mortality post MI, similar findings in epilepsy may indicate an increased cardiovascular risk in this group contributing to SUDEP. 1. Bigger JT, Fleiss JL, Steinman RC, Rolnitzky LM, Kleiger RE, Rottman JN. Frequency domain measures of heart period variability and mortality after myocardial infarction. Circulation. 1992;85(1):164-71. 2. Massetani R, Strata G, Galli R, Gori S, Gneri C, Limbruno U, et al. Alteration of cardiac function in patients with temporal lobe epilepsy: different roles of EEG-ECG monitoring and spectral analysis of RR variability. Epilepsia. 1997;38(3):363-9. 3. Tomson T, Ericson M, Ihrman C, Lindblad LE. Heart rate variability in patients with epilepsy. Epilepsy Res. 1998;30(1):77-83. 4. D tsch M, Hilz MJ, Devinsky O. Impaired baroreflex function in temporal lobe epilepsy. J Neurol. 2006;253(10):1300-8.