The Challenge of Choosing the Right Stimulation Target for Dystonic Tremor-A Series of Instructive Cases

Steffen Paschen; Jos S Becktepe; Markus A Hobert; Kirsten E Zeuner; Ann-Kristin Helmers; Daniela Berg; Günther Deuschl

doi:10.1002/mdc3.13846

The Challenge of Choosing the Right Stimulation Target for Dystonic Tremor-A Series of Instructive Cases

Mov Disord Clin Pract. 2023 Aug 22;10(10):1478-1484. doi: 10.1002/mdc3.13846. eCollection 2023 Oct.

Authors

Steffen Paschen¹, Jos S Becktepe¹, Markus A Hobert¹, Kirsten E Zeuner¹, Ann-Kristin Helmers², Daniela Berg¹, Günther Deuschl¹

Affiliations

¹ Department of Neurology University Hospital Schleswig-Holstein, Campus Kiel and Christian Albrechts-University of Kiel Kiel Germany.
² Department of Neurosurgery University Hospital Schleswig-Holstein, Campus Kiel and Christian Albrechts-University of Kiel Kiel Germany.

Abstract

Background: Thalamic deep brain stimulation (DBS) is established for medically refractory tremor syndromes and globus pallidus stimulation (GPi-DBS) for medically refractory dystonia syndromes. For combined tremor and dystonia syndromes, the best target is unclear.

Objectives: We present four patients with two different profiles whose clinical course demonstrates that our current analysis of clinical symptomatology is not a sufficient predictor of surgical success.

Methods: Outcome parameters were assessed with observer-blinded video ratings and included the Fahn-Tolosa-Marin-Tremor Rating Scale (FTM-TRS) and the Unified Dystonia Rating Scale (UDRS).

Results: Two patients with "predominant lateralized action tremor" of the hands and mild cervical dystonia showed no relevant tremor improvement after GPi-DBS, but UDRS improved (mean, 45%). Rescue ventral intermediate nucleus of the thalamus (Vim)-DBS electrodes were implanted and both patients benefited significantly with a mean tremor reduction of 51%.Two other patients with "axial-predominant action tremor of the trunk and head" associated with cervical dystonia underwent bilateral Vim-DBS implantation with little effect on tremor (24% reduction in mean FTM-TRS total score) and no effect on dystonic symptoms. GPi rescue DBS was implanted and showed a significant effect on tremor (63% reduction in mean FTM-TRS) and dystonia (49% reduction in UDRS).

Conclusions: The diagnosis of dystonic tremor alone is not a sufficient predictor to establish the differential indication of GPi- or Vim-DBS. Further criteria (eg, proximal-distal distribution of tremor/dystonia) are needed to avoid rescue surgery in the future. On the other hand, the course of our patients encourages rescue surgery in such severely disabled patients if the first target fails.

Keywords: dystonia; dystonic tremor; thalamic/pallidal deep brain stimulation.