Zona Incerta Stimulation Guided by Microelectrode-Defined Borders and MR/CT-Fusion for Tremor of Non-Parkinsonian Etiology

Peter C. Warnke, MD1, Catherine Ojakangas, PhD1, Jacqueline Bernard, MD1, Tao Xie, MD, PhD1

1Chicago, IL United States

Keywords: tremor, movement disorder, deep brain stimulation, magnetic resonance imaging, outcome

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     Deep brain stimulation for tremor (essential tremor,MS) has been performed in the ventral- intermediate thalamic nucleus (Vim) with good results. Recent reports have claimed superior results with zona incerta (ZI)-stimulation for tremor but either lack electrophysiological definition of the ZI during surgery or used inferior imaging for targeting.
     We tested the above hypothesis by performing ZI and Vim stimulation with rigorous microelectrode multichannel recording and 3T MRI/CT fusion plus for targeting.
     Six patients (3 ET,3MS) were enrolled into the study. All patients underwent combined 3T MRI/CT guided stereotactic explorations of the zona incerta using 3-5 microelectrode trajectories.
     The ZI as target was chosen after superposition of the Schaltenbrand Atlas. DBS lead implantation was performed 1-2 mm below the caudal physiological border of the Vim thus having 1-2 contacts in the ZI and 2 in the basal Vim allowing for differential stimulation. Electrode position was verified with postop CT fused to the stereotactic MRI/CT.
     All inferior contacts were in the ZI and also clearly above the STN on postoperative imaging. Tremor suppression regardless of etiology was superior with ZI-stimulation versus contacts in the Vim. Median voltage necessary for tremor suppression was significantly lower for ZI-stimulation as compared to Vim resulting in longer battery life. Microelectrode recording was significantly better in identifying the zona incerta than imaging alone( z- coordinate difference 2.3+0.4 mm, p<0.01).
     This is a retrospective study.
     DBS of the zona incerta is superior to Vim for tremor control including cerebellar outflow tremor.
     Microelectrode targeting is essential in defining the target.


Project Roles:

P. Warnke (), C. Ojakangas (), J. Bernard (), T. Xie ()