gms | German Medical Science

Objective: The subthalmic nucleus (STN) is the standard neuroanatomical target for deep brain stimulation (DBS) in Parkinson's Disease (PD). Usually, resting tremor can be satisfactorily suppressed by STN-DBS. However, in some patients especially with severe tremor STN-DBS does not suppress tremor sufficiently. In such cases the ventral intermediate nucleus (VIM) of the thalamus is an alternative target. There are case reports in the literature where additionally to STN-DBS a second set of electrodes – so called rescue leads – was additionally implanted bilaterally into the VIM with a better outcome. The opposite way around, in other cases the VIM was targeted first unilaterally without complete tremor suppression, however, after a second electrode implantation into the ipsilateral STN the tremor resolved completely. Here we report of 3 patients with tremordominant PD where the DBS-electrodes were implanted such that electrode-contacts are located in the STN and VIM and can be stimulated separately or simultaneously via the same electrode through a parietal surgical approach.

Method: In three patients (age 58, 74 and 81 years, 2 males and 1 female) with tremordominant PD we performed the parietal approach to stimulate VIM and STN with the same electrode. In all cases best medication did not lead to satisfying symptoms relief. UPDRS III off medication were 51/108, 35/108 and 36/108, respectively. The electrodes (Medtronic Inc.) were implanted bilaterally, the neurostimulator (Activa PC or Activa RC, Medtronic Inc.) was implanted subcutaneously in the infraclavicular region.

Results: In all cases we saw an excellent tremor supression and control of akinetic-rigid symptoms after at least one year. No treatment-related morbidity was observed.

Conclusions: This case study demonstrates in principle, that DBS electrodes can be safely implanted as such, that contacts are located in the VIM an STN for separate stimulation of one or simultaneous stimulation of both target areas. In the 3 patients implanted we saw a marked effect on tremor suppression and akinetic-rigid symptoms. Whether simultaneous stimulation of both targets is superior to conventional VIM- or STN-DBS in terms of tremor suppression, safety and intra- or postoperative side effects has to be evaluated in a future randomized controlled study.