Pre- and postoperative heart rate variability and vagus nerve stimulation in patients with drug-resistant epilepsy - A meta-analysis.

OBJECTIVE: The effect of vagus nerve stimulation (VNS), an important auxiliary therapy for treating drug-resistant epilepsy (DRE), on autonomic nerve function is still controversial. Heart rate variability is a widely used indicator of autonomic nerve function. To clarify the relationship between VNS and heart rate variability (HRV), we performed a meta-analysis to systematically evaluate the effect of VNS on HRV in patients with epilepsy. METHODS: We performed a systematic review by searching the following online databases: PubMed, Web of Science, EMBASE and the Cochrane Library. The key search terms were "vagal nerve stimulation," "epilepsy" and "heart rate variability". Other features of VNS in patients with epilepsy include postoperative changes in low-frequency (LF), high-frequency (HF) and low-frequency/high-frequency (LF/HF) heart rate variability, which were used as evaluation indices, and the Newcastle-Ottawa Quality Assessment Scale and Stata 14.0 statistical software were used for literature quality evaluation and meta-analysis. RESULTS: Twelve studies published in English were obtained, and 229 patients with epilepsy who underwent VNS were ultimately included after elimination of duplicate articles and those that did not meet the inclusion criteria. Regarding LF heart rate variability, in the response subgroup, patients with DRE with VNS presented a lower value (-0.58) before surgery than after surgery, with a 95% confidence interval (CI) ranging from -1.00 to -0.15. For HF heart rate variability, patients with DRE with VNS had a lower value (-0.45) before surgery than after surgery in the response subgroup, with a 95% CI ranging from -0.74 to -0.17. No differences were found for LF/HF values or the LF and HF values of other subgroups. CONCLUSION: VNS has little effect on the balance of sympathetic and parasympathetic nerve activity and would not be expected to cause cardiovascular autonomic dysfunction in patients with DRE. For patients with DRE, VNS can control seizures and has little effect on autonomic nervous function.

Perinatal outcome of recurrent pre-eclampsia versus pre-eclampsia in nulliparas.

AIM: The aim of the study was to compare the perinatal outcome of recurrent pre-eclampsia in multiparas with that of pre-eclampsia in nulliparas. METHODS: This retrospective study was performed by collecting maternal and perinatal data from records of women with pre-eclampsia who delivered at Mackay Memorial Hospital over a 10-year period. Fifty women with recurrent pre-eclampsia were compared with 207 women who developed pre-eclampsia as nulliparas. In the 50 multiparas, the outcome of recurrent pre-eclampsia was also compared with that of their earlier episodes of pre-eclampsia. Maternal and fetal variables compared included maternal blood pressure, serum biochemistry, rate of preterm delivery, rate of abruptio placentae and neonatal outcome. RESULTS: Compared with nulliparous women with pre-eclampsia (n = 50), women with recurrent pre-eclampsia (n = 207) had a smaller increase in mean maternal blood pressure (27.0 +/- 18.9 mmHg vs 34.3 +/- 19.3 mmHg, P = 0.021), less dipstick proteinuria (>or=++; 36.0 vs 58.5%, P = 0.004), and bore children with a heavier mean birthweight (2909.1 +/- 895.5 g vs 2551.1 +/- 933.0 g, P = 0.017). No significant statistical difference was found in the gestational age of delivery, maternal serum biochemical levels and rate of abruptio placentae or preterm delivery. Within the multiparous group (n = 50), recurrent disease was associated with a lower mean maternal blood pressure and dipstick proteinuria and with higher birthweight than in their previous pre-eclamptic pregnancies. CONCLUSION: Recurrent pre-eclampsia appears to be less severe and to have a better perinatal outcome than pre-eclampsia in nulliparas.