OBJECTIVE: To investigate the effect of directional current steering and short 
pulse stimulation in the ventral intermediate thalamic nucleus (VIM) on 
stimulation-induced side effects in patients with essential tremor.
METHODS: We recruited 8 patients with essential tremor in a stable postoperative 
condition (>3 months after electrode implantation of deep brain stimulation 
[DBS] electrodes) with segmented contacts implanted in the VIM. Tremor severity 
on acute stimulation was assessed by the Fahn-Tolosa-Marin Tremor Rating Scale. 
Cerebellar impairment was evaluated with the International Cooperative Ataxia 
Rating Scale. Patients rated paresthesia intensity with a visual analog scale.
RESULTS: In all patients, tremor was reduced to the same extent by VIM 
stimulation regardless of pulse width using energy dose-equivalent amplitudes. 
Short pulse stimulation diminished stimulation-induced ataxia of the upper 
extremities and paresthesia compared with conventional parameters. Directional 
steering with monopolar stimulation of single segments successfully suppressed 
tremor but also induced ataxia. No differences in adverse effects were found 
between single-segment stimulation conditions.
CONCLUSION: These proof-of-principle findings provide evidence that acute short 
pulse stimulation is superior to directional steering in the subthalamic area to 
decrease stimulation-induced side effects while preserving tremor suppression 
effects in patients with tremor.
CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for 
patients with tremor with thalamic DBS, acute short pulse stimulation reduces 
adverse effects, while directional steering does not provide a generalizable 
benefit regarding adverse effects.