Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Gait Characteristics in Parkinson's Disease

Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Gait Characteristics in Parkinson's Disease

Effect of Transcutaneous Auricular Vagus Nerve Stimulation at 25Hz and 100Hz on Levodopa Responsive and Non-responsive Gait Characteristics in Parkinson's Disease- a Motion Sensor Study

In this randomised placebo-controlled trial, the investigators will include 30 PD (Parkinson's disease) patients with HY (Hoehn Yahr stage) >2 and L-dopa unresponsive gait characteristics. Each participant will receive taVNS at 25Hz, taVNS at 100Hz and sham VNS (sVNS). During each stimulation, different gait characteristics will be measured with wearable insertion motion sensors.

Participants and study overview: In this randomised placebo-controlled trial, the investigators will include 30 PD patients with HY>2 and L-dopa unresponsive gait characteristics. Each participant will complete 1 visit, during which the instrumented stand and walk test will be repeated 16 times. The baseline measurement will be followed by three different stimulation conditions sham VNS (sVNS), taVNS at 25Hz (taVNS25) and taVNS a 100Hz (taVNS100). sVNS, taVNS25 and taVNS100 in a randomized order. To enhance gait disturbances, the participants will perform iSAW during each condition twice in silence and twice while simultaneously performing calculations around. Instrumented stand and walk test (iSAW): To perform iSAW, participants will first stand still for 30s, after which they will start walking in a straight line for 7m, turn and walk back to the start. The participants will be equipped with 6 inertion Opal ® motion sensors (on both feet, both wrists, on the lumbar back and on their sternum). For the laud counting iSAW condition (iSAW-C), the participants will perform iSAW as described above while also counting backwards by 3 from numbers above 100. TaVNS: Noninvasive electrostimulation will be applied to the left ear. taVNS will be applied to the cyma conchae and sVNS will be applied to the earlobe. Both taVNS and sVNS were applied through the Nemos® electrode with the following parameters: square-shaped pseudobiphasic pulse, interpulse duration 80μs, pulse width 300μs, pulse intensity 0,1mA above the perceptual threshold (figure 1). taVNS25 and sVNS will be applied at 25Hz and taVNS100 will be applied at 100Hz. The intensity for each separate stimulation will be adjusted for each participant at the beginning of the experiment. For each condition, the electrode will be placed in the ear by a third person and the ear will be covered by cotton pads and an EEG cap to hide the electrode position from the experimenter. The order of stimulation will not be revealed until the automated data and statistical analysis.

Participants and study overview In this randomised placebo controlled trial, the investigators will include 30 PD patients with HY>2 and L-dopa unresponsive gait characteristics. Each participant will complete 1 visit, during which the instrumented stand and walk test will be repeated 16 times. The baseline measurement will be followed by three different stimulation conditions sham VNS (sVNS), taVNS at 25Hz (taVNS25) and taVNS a 100Hz (taVNS100). sVNS, taVNS25 and taVNS100 in a randomized order. To enhance gait disturbances, the participants will preform iSAW during each condition twice in silence and twice while simultaneously performing calculations around.

Noninvasive electrostimulation will be applied to the left ear. taVNS will be applied to the cyma conchae and sVNS will be applied to the earlobe - participants will not be told which is the active and which is the sham condition. Both taVNS and sVNS were applied through the Nemos® electrode. The intensity for each separate stimulation will be adjusted for each participant at the beginning of the experiment. For each condition, the electrode will be placed in the ear by a third person and the ear will be covered by cotton pads and an EEG cap to hide the electrode position from the experimenter. The order of stimulation will not be revealed until the automated data and statistical analysis.

Participants will receive no stimulation, the electrode will be placed in the ear in a random position and turned off. Participants will complete 4 instrumented stand and walk tests - 2 without performing calculations and 2 with performing calculations aloud.

Noninvasive electrostimulation will be applied to the left cyma conchae through the Nemos® electrode at 100Hz. Participants will complete 4 instrumented stand and walk tests - 2 without performing calculations and 2 with performing calculations aloud.

Noninvasive electrostimulation will be applied to the left cyma conchae through the Nemos® electrode at 25Hz. Participants will complete 4 instrumented stand and walk tests - 2 without performing calculations and 2 with performing calculations aloud.

Noninvasive electrostimulation will be applied to the left earlobe through the Nemos® electrode at 25Hz. Participants will complete 4 instrumented stand and walk tests - 2 without performing calculations and 2 with performing calculations aloud.

Noninvasive electrostimulation will be applied to the left cyma conchae through the Nemos® electrode with the following parameters: square-shaped pseudobiphasic pulse, interpulse duration 80μs, pulse width 300μs, pulse intensity 0,1mA above the perceptual threshold at 100Hz. The intensity for each separate stimulation will be adjusted for each participant at the beginning of the experiment.

Noninvasive electrostimulation will be applied to the left cyma conchae through the Nemos® electrode with the following parameters: square-shaped pseudobiphasic pulse, interpulse duration 80μs, pulse width 300μs, pulse intensity 0,1mA above the perceptual threshold at 25Hz. The intensity for each separate stimulation will be adjusted for each participant at the beginning of the experiment.

Noninvasive electrostimulation will be applied to the left earlobe through the Nemos® electrode with the following parameters: square-shaped pseudobiphasic pulse, interpulse duration 80μs, pulse width 300μs, pulse intensity 0,1mA above the perceptual threshold at 25Hz. The intensity for each separate stimulation will be adjusted for each participant at the beginning of the experiment.

The average velocity of upper extremities in degrees per second as produced by the Mobility Lab software.

The average difference between left and right arm range of motion in degrees as produced by the Mobility Lab software.

The average duration of anticipatory postural adjustments in seconds as produced by the Mobility Lab software.

Inclusion Criteria: HYstage >2 L-dopa unresponsive gait characteristics present, preferably with history of freezings Exclusion Criteria: unable to walk for 50m unable to follow simple commands due to hearing loss/cognitive impairment