Objective: With the advancement of deep brain stimulation (DBS) techniques, a renewed interest in the posterior sub thalamic area (PSA) for the treatment of Parkinson’s disease (PD) and other tremor syndromes. In this study we aimed to evaluate the safety, efficacy and stimulation parameters for tremor control in DBS of caudal zona incerta (CZi).

Background: In tremor syndromes, most of the groups have reported that the most effective contact lies posterior and dorsomedial to the STN(sub thalamic nucleus) and in deeper contacts of VIM(ventral intermediate nucleus). The PSA is situated immediately inferior to the ViM and posteromedial to the STN (1). Narrow area carrying different fibers mainly cerebella thalamic (2,3) makes it more sustainable target area to stimulate many different fibers with single electrode. Effectiveness of PSA DBS is stimulation of axons instead of nuclei actually affects more neurons and therefore also alter tremor oscillations more efficiently.

Method: Twenty five consecutive patients (48 electrodes) with tremor-predominant PD and ET(essential tremor) who underwent CZi DBS were evaluated pre-surgically and post-surgically. Either TETRAS or UPDRS-III scheduled for the 6 month post-operative follow-up. Adverse effects were monitored which resulted from surgery and/or stimulation induced.

Results: In patients with ET, a baseline TETRAS score was 57+/-11 and in patients with PD, baseline UPDRS-III off medication, was 46+/-9. The tremor score improved by 90% and akinesia score improved by 30% at 6 months post-surgery. On average the stimulation parameters were amplitude of 2.1+/-0.6mA, pulse width of 70 +/- 10 microsec and frequency of 170+/-10 Hz. Transient adverse effects noted were Myoclonus, Dysarthria, somnolence and Depression and no surgical related complications were reported.

Conclusion: Caudal zona incerta DBS is an effective and promising treatment for patients with tremor syndromes and should be considered as alternative surgical target. Our results are similar to previous reported case series, but long term followup on these patients would be beneficial to look for effect sustainability.

References: 1. Plaha P, Ben-Shlomo Y, Patel NK, Gill SS. Stimulation of the caudal zona incerta is superior to stimulation of the subthalamic nucleus in improving contralateral parkinsonism. Brain 2006;129:1732e47 2. 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: 657–669; discussion 669–670. 3. Herzog J, Hamel W, Wenzelburger R, Potter M, Pinsker MO, Bartussek J, Morsnowski A, Steigerwald F, Deuschl G, Volkmann J: Kinematic analysis of thalamic versus subthalamic neurostimulation in postural and intention tremor. Brain 2007; 130: 1608–1625.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/deep-brain-stimulation-of-caudal-zona-incerta-case-series/