Optimal setting of vagus nerve stimulation parameters for antiepileptic treatment

Lanfeng ZHAO; Jingjin LI; Yangyuan AN

ABSTRACT

BACKGROUND:

The stimulation parameters concern directly the antiepileptic effect and safety of vagus nerve stimulation in epileptic patients, and the optimal setting of these parameters is crucial to ensure safe and effective application for antiepileptic treatment.

OBJECTIVE:

To observe the effect of such parameters as output current,wave width, frequency, on/off time of intermittent stimulation in electric vagus nerve stimulation for antiepileptic therapy.

DESIGN:

Single-sample experiment.

SETTING:

Department of Neurobiology, School of Basic Medical Sciences, Capital University of Medical Sciences.MATERIALS The experiment was carried out at Electrophysiological Laboratory of Department of Neurobiology, School of Basic Medical Sciences, Capital University of Medical Sciences between September 2000and September 2002, using totally 36 healthy adult Wistar rats.

METHODS:

Epileptic models were established in 36 healthy adult Wistar rats by cervical subcutaneous kainic acid injection, in which various settings of vagus nerve stimulation parameters were applied and their antiepileptic effects observed in terms of changes in the behaviors, electrocardiogram (ECG), electrocorticogram (ECoG), and hippocampal neuronal discharge to identify the optimal parameter setting.rameters.nerve stimulation produced antiepileptic effect mainly within 4 hours of with wave width of 2 ms, current intensity of 3-3.5 mA, frequency of 30-35 Hz, 1-minute on/2-minute off intermittent stimulation produced remarkable antiepileptic effect presented by obviously reduced seizure duration in ECoG and epileptic severity, with lowered frequency of bursting discharge in the epileptic rat CA1 neurons (P ＜ 0.05).

CONCLUSION:

With normal cardiac electric activity ensured, the minimum stimulation parameters sufficient for effective epilepsy control can be considered as the optimal parameter setting in electric vagus nerve stimulation, which has no adverse effect on the heart.