Deep brain stimulation in the nucleus ventralis intermedius in patients with essential tremor: habituation of tremor suppression

Abstract

In patients with essential tremor (ET) already treated with chronic deep brain stimulation (DBS) of the nucleus ventralis intermedius (VIM) we investigated whether optimization of stimulation parameters could improve clinical tremor suppression, and whether this putative effect could be sustained over time. Twenty-three ET patients with VIM-DBS participated in the prospective study. All electrode contacts were tested systematically and stimulation parameters were optimized over the course of 2 days. Clinical tremor rating scale (TRS) was videotaped before, directly after the optimization and at a 10 weeks follow-up and evaluated blindly and independently by two clinicians. For stimulation effect optimization we increased the number of active contacts whereas the total charge applied to the tissue was kept constant. TRS hemi-body scores decreased significantly after optimization. At the 10 weeks follow-up, however, the improvement had faded and was no longer significant. The activities of daily living (ADL) remained significantly improved. Systematic optimization of VIM-DBS parameters in ET patients leads to a short term improvement which habituates over time. Our results provide further evidence for a tolerance effect in chronic VIM stimulation thereby suggesting that frequently alternating stimulation protocols should be tested in future studies of ET patients treated with VIM-DBS.

Deep Brain Stimulation of the Caudal Zona Incerta: Tremor Control in Relation to the Location of Stimulation Fields

“…It has been shown for VIM DBS that a better effect on tremor can be achieved merely by switching between contacts from time to time, and a contact which produces a good effect upon activation may not continue to do so over time [21,22]. …”

Deep brain stimulation for movement disorders: update on recent discoveries and outlook on future developments

“…However, speech and balance problems were commonly noted in patients with bilateral stimulation. Moreover, the effect of thalamic stimulation on tremor may diminish over time [53,54] and overnight withdrawal from stimulation has been suggested to prevent tolerance effects. However, not all authors support the hypothesis that tolerance effects account for worsening of response to DBS over time and disease progression may additionally contribute to this phenomenon [55].…”

DBS in Dystonia and Other Hyperkinetic Movement Disorders

“…DBS failure immediately postoperative is mostly due to suboptimal electrode placement. A gradual loss of efficacy of DBS may be due to phenomena of tolerance [16] and might be prevented by overnight withdrawal from stimulation [36,37]. Worsening of tremor over time may also be secondary to disease progression [38].…”