gms | German Medical Science

Objective: Meanwhile the DBS of the Globus pallidus internus GPI is an established method in the treatment of some types of dystonia e.g. primary generalized dystonia and cervical dystonia, for other types only case reports or small series data exist. Surgery is usually performed under general anesthesia. Controversially discussed is the advancement in rare indications and some surgical aspects e.g. the need of using multiple trajectories for microrecording and intraoperative testing of side effects. The aim of the study was to control our surgical approach and to overview our indications.

Methods: We retrospectively analyzed data from all patients who had undergone DBS-surgery targeting the GPI in our department from 2005 to 2016, evaluating age, gender, indication for surgery, number of microelectrode trajectories, trajectory for the permanent electrode, reasons for avoiding the central trajectory, the intraoperative threshold for muscular contraction side effect on the chosen trajectory. Furthermore we related these gained information to the clinical outcome.

Results: In the studied period 107 surgeries targeting the GPI bilaterally due to dystonia were performed. Mean age was 45.3 ± 18.2 years (6 - 77 years). 85 (79.4%) patients were diagnosed with a form of primary dystonia e.g. eight patients were tested positive for the DYT1-mutation on chromosome 9q34.1. 22 (20.6%) patients suffered from a secondary dystonia. For intraoperative testing and microrecording we were able to use three or more microelectrodes in 86.3% of cases. In 39.4% of cases we implanted the final electrode over periphery trajectories due to a low threshold of muscular contraction side effects. We never changed the trajectory due to the microrecording. After placing the final electrode, the mean threshold for side effects was 4.53 Volt. Moreover, we compared these collected data to the long-term therapeutic effect.

Conclusion: Our study demonstrates large differences in the clinical outcome related to various types of dystonia. Although, the central trajectory was avoided in 39.4% of implantations after microrecording and intraoperative testing, we can’t detect an advantage due to using microrecording via multiple trajectories in GPI stimulation surgeries and changed our procedure to a first MRI single guided trajectory with only changing the trajectory due to a low threshold for side effects in form of muscular contractions.