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

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.

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.

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.

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.