Optimizing stimulation parameters for anterior thalamic nuclei deep brain stimulation in epilepsy: A randomized crossover trial.

OBJECTIVE

The effects of brain stimulation for diseases like epilepsy are delayed, making stimulation optimization difficult. The parameters for anterior thalamic nuclei (ANT) deep brain stimulation (DBS) for focal drug-resistant epilepsy management are often restricted to those used in the SANTE landmark trial. There is little evidence regarding effective alternatives, and low-frequency stimulation is typically neglected. We prospectively compare a widely differing stimulation parameter set to typical settings.

METHODS

This randomized, modified crossover, open trial compares the efficacy and safety of an alternative set of parameters using continuous low-frequency stimulation (cLFS) with a longer pulse width (7 Hz, 200 μs, continuous) compared to SANTE's intermittent high-frequency stimulation (iHFS) with a short pulse width (145 Hz, 90 μs, cycling 1 min on/5 min off). After 3 months on a randomly assigned first set, patients are switched to the other settings, unless seizure-free. Patients are re-evaluated after 3 more months, which marks the completion of the trial. After that, they can either remain on the same settings or switch back.

RESULTS

Sixteen patients with a median baseline seizure frequency of 13.8 seizures/month (interquartile range [IQR] = 2.7-22.8) were included in the analysis. At trial completion (median follow-up = 30 weeks, IQR = 26-35), ANT-DBS significantly reduced median seizure frequency (62%, IQR = 18-81, Wilcoxon test statistic [W] = 99, p = .008). Both iHFS (33%, IQR = 0-65, W = 81, p = .02) and cLFS (73%, IQR = 30-79, W = 105, p = .001) significantly reduced median seizure frequency. cLFS showed improved median seizure frequency reduction compared to iHFS (W = 63, p = .03) and was not associated with any moderate or severe adverse effects.

SIGNIFICANCE

Results support cLFS for ANT-DBS as a safe and effective alternative to typical iHFS parameters. Stimulation with widely differing parameter sets may be as effective as or, in some situations, more effective than typical stimulation parameters.