Better therapeutic efficiency of omnidirectional than directional subthalamic deep brain stimulation in Parkinson’s disease

Background Deep brain stimulation (DBS) using segmented electrode contacts allows for directionally steered stimulation (DS), while the conventional ring mode provides omnidirectional stimulation (OS). However, with regard to achieving better effects with the same stimulation intensity or equivalent effects with lower intensity, the comparative therapeutic efficiency of these approaches remains unclear. Objective To compare the therapeutic efficiency of subthalamic DBS using segmented and ring contacts in Parkinson’s disease (PD) patients with akinetic-rigid symptoms. Methods A double-blind, randomized monopolar review was conducted with patients in the dopaminergic medication-off state at 10 weeks postoperatively on three upper ring contacts and three contacts of the upper segmented level. Impedance measurements were obtained, and the therapeutic threshold (current strength for complete biceps brachii muscle rigidity resolution) was estimated by increasing stimulation intensity in 0.2 mA increments. Results OS with ring contacts showed an improved therapeutic threshold compared to DS with segmented contacts. At 1.1 mA stimulation intensity, complete rigidity resolution was achieved in 90% of patients with the best ring contact, whereas only 40% achieved the same outcome with the best segmented contact. In addition, OS with ring contacts exhibited 50% lower impedance than DS with segmented contacts. Conclusions Incremental adjustments in current intensity during parameter titration generate valuable stimulus-response curves for assessing therapeutic efficiency. In clinical practice, the monopolar review should give priority to identifying the optimal ring level and therapeutic threshold. Segmented contacts should be carefully considered as a potential alternative when side effects limit the feasibility of other options. ### Competing Interest Statement A.G. was supported by research grants from Medtronic, Abbott, Boston Scientific, all of which were unrelated to this work. D. W. was supported by travel grants, speaker honoraria and research grants from Abbott, Abbvie, Bial, Boston Scientific, Medtronic, Kyowa Kirin, Stadapharm, all of which were unrelated to this work. ### Clinical Trial NCT03548506 ### Funding Statement This investigator-initiated trial was supported by Abbott / St. Jude Medical (SANTOP). The funding had no impact on the study design, on the collection, analysis and interpretation of data, on the writing of the report or on the decision to submit the article for publication. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee of the Medical Faculty of Tuebingen, Germany gave ethical approval for this work I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data and evaluation code will be shared by the first author upon request. The toolbox FiNN ([Scherer et al., 2022][1]) that was used to analyze the data is available on GitHub. [1]: #ref-28