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

BackgroundDeep 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. ObjectiveTo compare the therapeutic efficiency of subthalamic DBS using segmented and ring contacts in Parkinsons disease (PD) patients with akinetic-rigid symptoms. MethodsA 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. ResultsOS 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. ConclusionsIncremental 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.