Stimulation site within the MRI‐defined STN predicts postoperative motor outcome

Abstract

High-frequency stimulation of the subthalamic nucleus (STN-HFS) is highly effective in treating motor symptoms in Parkinson's disease (PD) and medication side effects as well as in improving quality of life. Despite preoperative screening for patients as eligible candidates for this treatment, electrode position may furthermore influence treatment quality. Here, we investigated the relationship between the anatomical site of stimulation within the MRI-defined STN and the outcome of PD patients after STN-HFS. In 30 PD patients with bilateral STN stimulation, we retrospectively defined the boundaries of the STN within the axial target plane of the stereotactic T2-weighted MRI and determined the position of the active electrode contact in relation to the border of the STN. The position of the active contact within the STN was the only variable to predict the outcome of STN stimulation. In contrast, covariates such as age, disease duration, symptom severity, and response to levodopa had no effect. The lateral position of the stimulation contact within the STN led to significantly better clinical improvement, lower stimulation parameters, and less need for postoperative dopaminergic medication. The outcome of patients with stimulation contacts within the medial region of the STN was significantly worse. Precise targeting of the lateral region of the STN is essential for achieving sufficient stimulation efficacy. Preoperative T2-weighted MRI might be a useful component of the targeting procedure to improve the outcome of PD patients.

Stimulation sites in the subthalamic nucleus projected onto a mean 3-D atlas of the thalamus and basal ganglia

“…Our finding of the median of the optimal stimulation sites in the dorso-lateral STN agrees with reports that stimulation in the dorso-lateral STN [5,22] improves motor symptoms in PD patients. …”

“…DBS has become a standard treatment for patients with advanced Parkinson's disease (PD). For many patients a site within the subthalamic nucleus (STN) is chosen as an efficient target site to improve motor symptoms [3,5,6,22].…”

Directional leads for deep brain stimulation: Opportunities and challenges

“…DBS has been used successfully for many years in movement disorders such as Parkinson's disease (PD), [1][2][3] yet treatment may sometimes be suboptimal for several different reasons, such as inappropriate patient selection or programming or electrode placement; two referral centers for DBS troubleshooting have reported that therapy failure in half of the evaluated leads was caused by suboptimal positioning. 4 Stimulation of the dorsolateral subthalamic nucleus (STN) is associated with best motor symptom control, 5,6 but excessive stimulation of adjacent fiber tracts can cause adverse effects such as disturbances in speech and fine-motor control. 7,8 Small lead deviations from the intended functional target play an important role in suboptimal efficacy 6 and side effects, 9 even in experienced surgical centers.…”

“…4 Stimulation of the dorsolateral subthalamic nucleus (STN) is associated with best motor symptom control, 5,6 but excessive stimulation of adjacent fiber tracts can cause adverse effects such as disturbances in speech and fine-motor control. 7,8 Small lead deviations from the intended functional target play an important role in suboptimal efficacy 6 and side effects, 9 even in experienced surgical centers. 6 Even with a seemingly optimal lead position, functional targets vary from patient to patient, and axial displacements may still lead to adverse effects.…”

“…7,8 Small lead deviations from the intended functional target play an important role in suboptimal efficacy 6 and side effects, 9 even in experienced surgical centers. 6 Even with a seemingly optimal lead position, functional targets vary from patient to patient, and axial displacements may still lead to adverse effects. Some stimulation targets, such as fiber tracts, tend to be nonspherical, making them more difficult to optimally capture with conventional lead geometries.…”