Objective: To investigate how subthalamic nucleus deep brain stimulation (STN-DBS) modulates cortical activation during kinesthetic illusion (KI) in Parkinson’s disease (PD).

Background: There is increasing evidence that PD is associated with impaired kinesthetic perception and abnormal sensorimotor integration (1,2). While STN-DBS improves motor symptoms, its influence on cortical networks underlying kinesthetic processing remains unclear.

Method: Eight right-handed PD patients (mean age 64 ± 5.2 years; 7 males) with bilateral STN-DBS completed a KI task under two conditions: DBS OFF and DBS ON (clinically optimized settings; only the left [contralateral] STN-DBS was activated during the ON condition to investigate the lateralized effects). Each run alternated between tendon-vibration and bone-vibration blocks. During tendon-vibration, a nonmagnetic air-pressure-driven vibrator stimulated the right extensor carpi ulnaris tendon, inducing illusory wrist flexion. Participants indicated the maximum perceived angle of illusory flexion by actually flexing their wrists, and the angle was measured with a protractor. For bone-vibration periods, vibration was applied to the right ulnar styloid process, eliciting sensations without illusions. Brain activation during tendon vs. bone vibration was compared across DBS states. Motor severity was assessed with the MDS-UPDRS-III.

Results: The mean maximum illusory flexion angle during DBS ON was 8°. In the DBS OFF state, task-related activation was reduced and confined to frontal and motor regions. In contrast, DBS ON revealed more widespread recruitment across the supplementary motor area, motor cortex, prefrontal cortex, parietal, and temporal regions, which are implicated in kinesthetic processing and sensorimotor integration. Clinically, MDS-UPDRS-III scores improved from 43.5 (OFF) to 20.25 (ON), reflecting a 53.4% reduction in motor severity.

Conclusion: STN-DBS promotes widespread cortical engagement during KI, extending beyond motor regions to frontoparietal and temporal networks involved in sensorimotor integration. These findings suggest that, in addition to improving motor symptoms, DBS facilitates sensorimotor integration, thereby supporting kinesthetic perception in PD.

DBS-ON brain activation patterns

DBS-OFF brain activation patterns

References: 1. Permezel F, Alty J, Harding IH, Thyagarajan D. Brain Networks Involved in Sensory Perception in Parkinson’s Disease: A Scoping Review. Brain Sci. 2023;13:https://doi.org/10.3390/brainsci13111552.
2. Conte A, Khan N, Defazio G, Rothwell JC, Berardelli A. Pathophysiology of somatosensory abnormalities in Parkinson disease. Nat Rev Neurol. 2013;9:687-97. https://doi.org/10.1038/nrneurol.2013.224.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/subthalamic-nucleus-deep-brain-stimulation-modulates-cortical-activation-during-kinesthetic-illusion-in-parkinsons-disease-an-fmri-study/