Neurophysiological and Clinical Effects of Low-intensity Transcranial Ultrasound of the Motor Cortex in Parkinson’s Disease
Talyta Grippe1, Yazan Shamli Ogghli2, Can Sarica1, Cricia Rinchon2, Jean-François Nankoo1, Robert Chen3
1University Health Network, 2Medicine, University of Toronto, 3Toronto Western Hospital
Objective:

Evaluate the neurophysiological and clinical effects of transcranial ultrasound stimulation (TUS) of motor cortex (M1) in PD patients.

Background:

Low-intensity TUS is a non-invasive brain stimulation technique that can reduce cortical excitability during sonication (online effect). TUS in a theta burst (tb) mode (tbTUS) can increase cortical excitability (offline or plasticity effect). PD have altered cortical excitability, and benefit from non-invasive stimulation of M1.

Design/Methods:

Eleven PD patients (2F, age 60.7±7.7 [mean±SD] years) were evaluated in ON and OFF dopaminergic medication states, and 16 controls (6F, age 65.6±10 years). The online protocol consisted of M1 TUS of 20W (active) and 0W (sham), with simultaneous transcranial magnetic stimulation measures of motor-evoked potential (MEP) amplitude. The offline protocol was 80 seconds of M1 tbTUS at 20W contralateral to the more affected side. MEP was recorded at baseline (before tbTUS), at 5-minutes (T5), T30, and T60 after tbTUS. Motor (m)UPDRS was evaluated in PD at baseline and at T60.

Results:

Online TUS did not reduced MEP amplitudes. For offline effects, a linear mixed model on MEP amplitudes showed a significant effect of time (F=2.8, p=0.046) and trend for time x group interaction (F=2.23, p=0.092) comparing PD-OFF and controls. There was a significant effect of time (F=4.17; p=0.009) but not group comparing PD-ON and controls. There was a trend for an effect of group (F=3.47; p=0.069) comparing MEP ratios for PD-ON and PD-OFF. The mUPDRS was significantly reduced at T60 (ON 24.1 ± 2.1; OFF 29.3 ± 1.7 [mean ± SE]) compared to baseline (ON 29.5 ± 2.3; OFF 30.8 ± 62.0 (paired t-test, ON p=0.004, OFF p=0.064) in PD-ON group.

 

 

Conclusions:
Increased M1 excitability following tbTUS also occurs in older controls and PD-ON, but not in PD-OFF. The mUPDRS reduction indicate a possible clinical effect in PD-ON. The study is ongoing, and more subjects are being recruited.
10.1212/WNL.0000000000203886