Anodic and symmetric biphasic pulses enlarge the therapeutic window in deep brain stimulation for essential tremor

Since the inception of DBS, cathodic pulses have been used.

To investigate the effect of anodic and symmetric biphasic pulses on the therapeutic window (TW) in essential tremor (ET) patients.

A randomized, doubled-blinded, cross-over design was used to test the effect of cathodic, anodic and symmetric biphasic pulses (cathode-first and anode-first) on the TW in an acute clinical setting. TW was defined as the difference between the minimal stimulation amplitude provoking side effects and minimal stimulation amplitude inducing tremor arrest.

9 ET patients (10 hemispheres) were included. Anodic stimulation induced a significantly larger TW compared to cathodic stimulation (p = 0.008). Symmetric biphasic stimulation also widened the TW compared to cathodic stimulation for both cathode- (p = 0.047) and anode-first (p = 0.008) biphasic pulses. For both anodic and biphasic pulses, the effect on TW was mainly driven by the change in side effect threshold. The order of the phases in the biphasic pulse had a significant effect on the side effect threshold (p = 0.039), with biphasic-anode first having the highest value. All pulse shapes were safe in the acute setting.

Anodic and symmetric biphasic pulses increase TW in ET patients.