Session Time: 1:15pm-2:45pm
Location: Les Muses Terrace, Level 3
Objective: To investigate the relation between the efficiency of deep brain stimulation (DBS) of the posterior subthalamic area (PSA) and the ventral intermediate nucleus (VIM) and the distance to the dentatorubrothalamic tract (DRTT) in essential tremor (ET).
Background: DBS of the PSA and the VIM is an established, effective and safe treatment for medication-refractory ET patients.  Previous studies showed that direct targeting of the DRTT to modulate the tremor network via cerebellothalamic connections leads to successful tremor control.  However, a direct correlation between the clinical outcome and the distance to the DRTT has not yet been proven.   
Method: Tremor rating scale (TRS) hemi‑scores were analyzed in 13 ET patients with DBS electrodes implanted into both the VIM and the PSA who were stimulated in both targets separately as part of a prospective, randomized, crossover trial.  Distances of the active electrodes to population‑based averaged DRTTs were calculated. The relationships between distance to DRTT and stimulation amplitude, as well as DBS efficiency (TRS improvement per amplitude) were investigated.
Results: PSA electrodes were closer to the DRTT (p = 0.023) and led to a greater improvement in TRS hemi‑scores (p = 0.005) than VIM electrodes. Proximity to the DRTT was related to lower stimulation amplitudes (p < 0.001) and higher DBS efficiency (p = 0.009).
Conclusion: Differences in tremor outcome and stimulation parameters between electrodes in the PSA and the VIM can be explained by their different proximities to the DRTT. Direct targeting of the DRTT should be explored to further improve DBS outcomes in tremor patients.
References:  Barbe MT, Reker P, Hamacher S, et al. DBS of the PSA and the VIM in essential tremor: A randomized, double-blind, crossover trial. Neurology 2018;91(6):e543-e550.  Fenoy AJ, Schiess MC. Deep Brain Stimulation of the Dentato-Rubro-Thalamic Tract: Outcomes of Direct Targeting for Tremor. Neuromodulation 2017;20(5):429-436.  Fenoy AJ, Schulz P, Selvaraj S, et al. Deep brain stimulation of the medial forebrain bundle: Distinctive responses in resistant depression. J Affect Disord 2016;203:143-151.  Coenen VA, Allert N, Paus S, Kronenburger M, Urbach H, Madler B. Modulation of the cerebello-thalamo-cortical network in thalamic deep brain stimulation for tremor: a diffusion tensor imaging study. Neurosurgery 2014;75(6):657-669; discussion 669-670.  Schlaier J, Anthofer J, Steib K, et al. Deep brain stimulation for essential tremor: targeting the dentato-rubro-thalamic tract? Neuromodulation 2015;18(2):105-112.
To cite this abstract in AMA style:JN. Petry-Schmelzer, T. Dembek, P. Reker, J. Wirths, S. Hamacher, J. Steffen, H. Dafsari, M. Hövels, G. Fink, V. Visser-Vandewalle, M. Barbe. PSA and VIM DBS efficiency in essential tremor depends on distance to dentatorubrothalamic tract [abstract]. Mov Disord. 2019; 34 (suppl 2). https://www.mdsabstracts.org/abstract/psa-and-vim-dbs-efficiency-in-essential-tremor-depends-on-distance-to-dentatorubrothalamic-tract/. Accessed September 22, 2023.
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MDS Abstracts - https://www.mdsabstracts.org/abstract/psa-and-vim-dbs-efficiency-in-essential-tremor-depends-on-distance-to-dentatorubrothalamic-tract/