Sensory Function Improves With Subthalamic Nucleus Stimulation in Parkinson's: A Network Analysis

Sensory dysfunction is common in Parkinson disease (PD) and may impair motor function and quality of life. Although subthalamic nucleus deep brain stimulation improves motor symptoms, it also modulates sensory function. This study aimed to identify stimulation sites and structural brain networks associated with improvements in sensory decision making.

Data from 21 patients with PD treated with subthalamic nucleus deep brain stimulation were retrospectively analyzed. Sensory decision making was assessed using the rubber hand illusion. Measures included proprioceptive drift (shift in perceived hand position), hand stroking illusion (questionnaire-rated visual-tactile synchrony), and hand ownership illusion (feeling the rubber hand is one's own) in stimulation-on and stimulation-off conditions. Computational software modeled stimulated tissue for each patient, identifying optimal stimulation sites ("sweetspots"). A normative connectome determined networks associated with outcome improvement and worsening. Results were validated with permutation testing. A region-of-interest (ROI) analysis examined contributions from sensorimotor and prefrontal brain regions.

Normalization of right-hand proprioceptive drift (reduction toward control levels) was associated with stimulation of the left associative-limbic subthalamic nucleus and with bilateral prefrontal cortex (PFC) connectivity. Improvement in the right-hand stroking illusion correlated most strongly with contralateral motor and prefrontal connectivity. ROI analysis showed that proprioceptive drift improvement was linked to bilateral executive and limbic networks, whereas right-hand stroking illusion improvement involved contralateral executive, limbic, and somatomotor networks.

Stimulation of the associative-limbic subthalamic nucleus and connectivity to the PFC are important for improving sensory decision making in PD. These effects may reflect modulation of sensory decisional conflict resolution networks. Understanding these relationships may support individualized, symptom-based stimulation therapies. These exploratory findings warrant further study.