Transcranial Ultrasound Stimulation of Internal Globus Pallidus Region and Motor Cortex in Parkinson's Disease

Many patients with Parkinson's disease (PD) have motor impairments despite dopaminergic therapy. Low-intensity transcranial ultrasound stimulation (TUS) is a non-invasive neuromodulation method with high spatial precision. The effects of motor cortex (M1) and internal globus pallidus (GPi) TUS on PD motor signs and cortical excitability are still uncertain.

To compare the effects of M1 theta burst TUS (tbTUS), GPi region tbTUS, and dual-site (M1 + GPi region) tbTUS on neurophysiology and motor signs in PD patients.

Sequential bilateral real M1/sham GPi, real GPi/sham M1, and simultaneous dual-site tbTUS were administered in three separate study visits in random order to 13 PD patients. Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale-Part III (MDS-UPDRS-III) scores and transcranial magnetic stimulation measures of cortical excitability were recorded at baseline and at several time points up to 60 min after sonication.

MDS-UPDRS-III scores and bradykinesia subscores decreased compared with baseline after GPi tbTUS at 30 min after sonication. Motor evoked potential (MEP) ratio to baseline increased after M1 tbTUS compared with GPi tbTUS at 10 min after sonication (T10). The stimulation intensity to elicit 1 mV MEP ratio to baseline in the GPi tbTUS condition was higher compared with baseline and with M1 tbTUS and dual-site tbTUS at T10. MEP amplitudes and MDS-UPDRS-III scores did not significantly change after the M1 and dual-site tbTUS conditions.

Bilateral GPi region tbTUS is a potential non-invasive approach for improving motor signs in PD patients, particularly bradykinesia. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.