Short and Long-term Responses of PD Symptoms to Earstim

Inclusion criteria

• Patients fulfilling the following criteria are eligible for participation:
• Subject must be ≥44 years of age.
• Subject has PD and is on stable carbidopa/levodopa therapy for at least four weeks prior to enrollment in the study.
• Subject must be willing and able to refrain from changing PD medications or dosages during the 90-day study.
• Subject reports experiencing both "ON" and "OFF" episodes (MDS-UPDRS Part IV - Time Spent in the OFF-state score ≥1), as assessed and determined by the investigator.
• \*This corresponds to item 4.3 in MDS-UPDRS Part IV, where a score of 0 (zero) indicates that the subject experiences no OFF periods during the waking day, and a score of ≥1 reflects the presence of OFF periods at any level.
• Subject experiences "OFF" periods with an "ON" score that is ≥20% better than the "OFF" score, as measured by the MDS-UPDRS Part III score, 1 hour after taking their dose of carbidopa/levodopa.
• Subject has an MDS-UPDRS Part III score ≥33 in "OFF" period.
• Subject agrees to remain in an "OFF" period for up to 3 hours without requiring rescue medication.
• Subject can walk independently, without the use of an assisted device (e.g., cane or walker), in both "ON" and "OFF" periods.
• Subject is willing to provide informed consent to participate in the study.
• Subject is willing and able to comply with all study procedures and required availability for study visits.

Exclusion criteria

• Patients who meet any of the following criteria are to be excluded from participation:
• Subject has a medical or psychiatric comorbidity that may compromise participation in the study.
• Subject has a history of cardiac rhythm disorders (e.g., atrial fibrillation, ventricular tachycardia, or atrioventricular block).
• Subject is pregnant or planning to become pregnant during the course of the study.
• Subject has a form of Parkinsonism other than PD, such as drug-induced Parkinsonism or Multiple System Atrophy.
• Subject is currently using on-demand medications for PD, such as subcutaneous apomorphine, sublingual apomorphine, and levodopa inhalation powder.
• Subject has an implanted deep brain stimulator (DBS).
• Subject is receiving direct intestinal infusions of levodopa.
• Subject has a history of epilepsy.
• Subject's medications are expected to change during the 90-day study period.
• Subject has a cardiac pacemaker, defibrillator, bladder stimulator, spinal cord stimulator, or any other active electronic medical device.
• Subject is unable to understand or follow the instructions required by the study.
• Subject has an ear infection or skin condition around the ear.
• Subject is participating, or has participated, in another interventional clinical trial in the last 30 days that may confound the results of this study, unless approved by the Sponsor.
• Subject has a history of brain surgery or peripheral neuropathy.
• Subject is actively using TENS or has a history of chronic TENS use within the last 2 weeks prior to study enrollment.
• Subject consumed alcohol or caffeine within 12 hours of study enrollment or has a history of alcohol dependence