Transcutaneous Vagal Nerve Stimulation (tVNS)tVNS_PDNCT07588191
Effects of Transcutaneous Vagus Nerve Stimulation in Parkinson´s Disease
A study testing Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve, Conventional Physical therapy and Conventional Speech Therapy in people with Transcutaneous Vagal Nerve Stimulation (tVNS) and Parkinson Disease (PD), run by Universidade da Coruña at 1 site in Spain.
Trial summary
This study aims to determine whether electrical stimulation of the ear, when combined with physical and speech therapy, can improve symptoms in subjects diagnosed with Parkinson´s disease, by comparing two different application sites. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Transcutaneous Vagal Nerve Stimulation (tVNS), Parkinson Disease (PD)
- What is being tested?
- Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve, Conventional Physical therapy and Conventional Speech Therapy
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 46 participants
- Where
- 1 siteSpain
- Study dates
- 25 May 2026to Nov 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Being a member of the Association or be interested in joining;
- Idiopathic PD diagnosis, stages 2-3 according to the Hoehn \& Yahr scale; confirmed by neurologist
- Ability to walk independently for at least 1 minute ant turn 180° without assistance;
- Exhibiting symptoms of hypokinetic dysarthria;
- On stable dopaminergic therapy for at least 1 month prior to the experiment
Who cannot join
- Any contraindication for taVNS (e.g., ear lesions, pacemakers, defibrillators, or other electronic devices)
- Previous vagotomy or previous application of electrical stimulation to the ear or brain, or treatment with high-intensity focused ultrasound (HIFU)
- Voice or speech disorders caused by other medical conditions
- MoCA score below 21
- Psychotic symptoms or hallucinations; a diagnosis of psychiatric illness
- Systolic blood pressure above 160 mm Hg, and diastolic blood pressure above 100 mm Hg
- Inability to attend sessions;
- Concomitant neurological, orthopaedic, cardiac, respiratory or active medical/oncological condition that would affect participation
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effects of Transcutaneous Stimulation of the Auricular Branch of the Vagus Nerve in Parkinson´s Disease
This study aims to determine whether electrical stimulation of the ear, when combined with physical and speech therapy, can improve symptoms in subjects diagnosed with Parkinson´s disease, by comparing two different application sites.
Each subject will undergo an initial in-person screening and provide consent before participating in the study.
Read more
The main questions to answer are:
- Does transcutaneous electrical nerve stimulation (tVNS) in the ear paired with physical and speech therapy improve speech and voice-related problems, airway protection, salivation, and swallowing?
- Does tVNS paired with physical and speech therapy improve tremor, walking speed, and balance in people with PD?
- Does tVNS paired with physical and speech therapy improve heart rate and heart rate variability in people with PD?
- Do its effects persist at 8 weeks?
Participants will:
Attend 12 rehabilitation sessions over 4 weeks (three per week). During each session, participants received either active or sham tVNS, accompanied by speech therapy (once per week), physical therapy (once per week), or conducted alone (once per week).
Undergo speech, voice, swallowing, respiratory, gait, balance, tremor, heart rate variability, and cognitive testing, as well as questionnaires regarding the quality of life, before and after treatment.
Return for a follow-up visit eight weeks after therapy to check how long the effects last.
Read the detailed description
Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. Most people with PD will experience dysfunction of the autonomic nervous system (ANS), although the severity of this dysfunction can vary widely, affecting both physical and mental well-being. Symptoms are typically classified as motor or non-motor. Prominent motor symptoms of PD include bradykinesia, rigidity, tremor, and abnormalities in gait, balance, and posture. These symptoms are associated with falls and have a very negative impact on quality of life. In addition, impaired fine motor skills, combined with respiratory and other problems, significantly affect voice, speech, and swallowing, as well as other non-motor disorders, such as neuropsychiatric, sleep, sensory, and digestive disorders.
This study is a double-blind, randomized, controlled trial designed to evaluate the efficacy of transcutaneous auricular vagus nerve stimulation on the motor and non-motor effects of Parkinson´s Disease (PD). Investigators will recruit up to 46 patients. The volunteers will be randomized by sex and the Hoehn and Yahr stage. Clinical information and, specifically, Unified Parkinson's Disease Rating Scale (UPDRS) -III (section III) will be assessed initially.
The primary variable of the study will be voice variables, such as volume, jitter, and shimmer. The remaining dependent variables will be other voice and acustic measures; the presence and severity of dysphagia; the presence and severity of xerostomia and sialorrhea; swallowing efficiency, peak cough flow; the level of tremor; the severity of gait dysfunction; balance; cognitive ability regarding concentration and response inhibition; heart rate and heart rate variability; quality of life in PD; adverse effects; and the degree of effectiveness of blinding.
Over the course of 4 weeks, participants will receive 30-minute stimulation sessions three times weekly, along with physiotherapy and speech therapy once per week. One group will be assigned to stimulation in the cymba concha (where the vagus nerve is placed) and the other (sham) in the earlobe.
Data collection will occur at baseline (T0), post-intervention (T1- 4 weeks), and 8 weeks after finishing the intervention (T2), except for the intensity required to administer electrical stimulation and adverse effects, which will be studied during the whole intervention. Tolerance will be assessed on day 1 of stimulation and on day 12 (4 weeks). Statistical analyses will employ mixed-model approaches to evaluate changes in outcome measures over time and between interventions.
- Being tested
- Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve, Conventional Physical therapy, Conventional Speech Therapy, Sham Transcutaneous Electrical Stimulation of Vagus Nerve
- Keywords
- transcutaneous electrical nerve stimulation, Vagus Nerve, Parkinson Disease, Speech Therapy, Physical Therapy Modalities, Deglutition, Tremor, Posture, Gait, Quality of Life, cognition, cough, Sialorrhea, Xerostomia, Heart Rate, voice disorders, Ear
- Medical subject headings
- Parkinson Disease, Communication Disorders, Tremor, Cough, Sialorrhea, Xerostomia, Voice Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus NerveDevice
Also called tVNS, taVNS, transcutaneous auricular vagus nerve stimulation
The tVNS will be performed at 200 microseconds, with frequencies ranging from 20 to 200 Hz (30 seconds/30 seconds) for 30 minutes, in the area innervated by the auricular branch of the vagus nerve (cymba concha and concha). The individually titrated intensity will be set above the sensory threshold (intense tingling sensation) but below the level of discomfort.
Conventional Physical therapyOther
Physical therapy delivered to both groups consists of exercises aimed at posture alignment and body coordination, static and dynamic balance improvement, and gait quality. It will be delivered once a week, during a session of electrical stimulation.
Conventional Speech TherapyOther
It will focus on the orofacial muscles, the acquisition of a diaphragmatic-abdominal breathing pattern that integrates breathing with vocal production, voice training with exercises that enhance vocal quality and prosody, articulation exercises to improve speech clarity, and swallowing training. It will be administered once a week, during one of the three electrical stimulation sessions.
Sham Transcutaneous Electrical Stimulation of Vagus NerveDevice
Also called Sham location, sham-tVNS, sham- taVNS, sham transcutaneous vagus nerve stimulation
The sham- tVNS will be performed at 200 microseconds, with frequencies ranging from 20 to 200 Hz (30 seconds/30 seconds) for 30 minutes, with electrodes placed on the earlobe, which lacks vagus nerve innervation. The individually titrated intensity will be set above the sensory threshold (intense tingling sensation) but below the level of discomfort.
| Study group | Role | What they receive |
|---|---|---|
| Active tVNS paired with conventional Speech Therapy and Physical Therapy | Active comparator | Participants in this arm will receive transcutaneous electrical stimulation applied to the concha of the left ear for 30 minutes, three times a week, over a 4-week period. This location is known to be innervated by the auricular branch of the vagus nerve. In addition, a speech therapy session and a physical therapy session will be added once a week each, while receiving the electrical stimulation. Receives: Device: Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve; Other: Conventional Physical therapy; Other: Conventional Speech Therapy |
| Sham tVNS paired with Speech Therapy and Physical Therapy | Sham comparator | Participants in this arm will receive the same transcutaneous electrical stimulation as the active group, but applied to the earlobe, a site not innervated by the vagus nerve. The procedure, the appearance of the device, and the parameters are identical to those of the active condition to maintain participant blinding. In addition, a speech therapy session and a physical therapy session will be added once a week each, while receiving the electrical stimulation. Receives: Other: Conventional Physical therapy; Other: Conventional Speech Therapy; Device: Sham Transcutaneous Electrical Stimulation of Vagus Nerve |
What is being measured
The primary outcome is the main question the study is designed to answer.
Voice intensity
The PRAAT software will be used to test the voice twice, when sustaining till 10 seconds the vowel "a" and when reading a text at their usual volume. The intensity (voice volume, measured in decibels) will be recorded.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Voice- Jitter
It is derived from the sustaining till 10 seconds the vowel "a". Then, PRAAT software will be used to test the voice, discarding the beginning and the end. The Jitter is defined as the variation in frequency from cycle to cycle, a measure of vocal instability, expressed as a percentage. The higher the percentage, the more irregularities the voice will have.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Voice- Shimmer
It is derived from the sustaining till 10 seconds the vowel "a". Then, PRAAT software will be used to test the voice, discarding the beginning and the end. The Shimmer refers to the variation in the amplitude of the sound wave. It is a measure of vocal instability, expressed as a percentage. The higher the percentage, the more irregularities the voice will have.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Secondary outcomes (22)
Voice fundamental frequency (F0)
The PRAAT software will be used to test the voice twice, when sustaining till 10 seconds the vowel "a" and when reading a text at their usual volume. The fundamental frequency (F0) is the oscillation originating from the vocal folds. It will be recorded in Hz.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Harmonic to Noise Ratio (HNR)
The PRAAT software will be used to test the voice twice, when sustaining till 10 seconds the vowel "a" and when reading a text at their usual volume. The Harmonic to Noise Ratio (HNR), a measure of the ratio between the periodic and non-periodic components that make up a segment of spoken voice, will be recorded. This ratio reflects the efficiency of sound production; that is, the greater the amount of airflow converted from the lungs into vocal cord vibration energy, the higher the HNR will be. A low HNR indicates a weak voice and dysphonia.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Maximum phonation time (MPT)
The participant will be asked to sustain the vowel /a/ for as long as possible after a deep inhalation. It will be repeated three times, and the best value will be recorded. The maximum phonation time (MPT) will be measured in seconds. The same procedure will be taken for the /s/.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Maximum expiratory time during sustained /s/
The participant will be asked to sustain the /s/ sound for as long as possible after a deep inhalation. It will be repeated three times, and the best value in seconds will be recorded.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Index s/a
The index s/a is used to compare respiratory with laryngeal function, based on the assumption that the two are similar, so the ratio should be 1.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Diadihokinetic rates (DDK)
Diadochokinesis measures the ability to perform rapid, alternating muscle movements in a repetitive manner. It assesses the rate and regularity of consonant-vowel repetitions /pa-ta-ka/. The individual is instructed to repeat the syllables /pa-ta-ka/ as quickly and accurately as possible for 10 seconds. The higher the value, the better.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Self-perceived handicap associated with dysphonia: Voice Handicap Index (VHI-10)
The Voice Handicap Index- 10 (VHI-10) is a valid instrument for assessing self-perceived disability associated with dysphonia. It consists of 10 items designed to evaluate patients´ perception of the impact of voice disorders on their quality of life. Each item contains specific questions related to the functional, emotional, and physical aspects of the voice. The patient must answer on a Likert-type scale with options ranging from 0 (never) to 4 (always). The total score is obtained by summing the responses, with a range of 0 to 40, where higher scores indicate a greater degree of vocal impairment.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Salivation
To measure salivation, a dry cloth will be placed in the mouth and weighed after 2 minutes without swallowing to estimate the volume of saliva produced. Changes in weight will be recorded. A higher final weight-and thus a greater difference-indicates increased saliva production.
Measured: Baseline (T0), post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Swallowing- dysphagia
It will be measured by Repetitive Saliva Swallowing Test (RSST), where the patient is asked to swallow saliva as many times as possible for 30 s, while deglutition is counted through palpation of the larynx. A value below 3 swallows has been found to be pathological.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Cookie Swallow Test
Time will be measured (velocity), swallow security and efficacy, checking for any residue after swallowing.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Timed Water Swallow Test (TWST)
The time taken to consume 150 mL of bottled water and the swallowing capacity (mL/s) will be measured, as well as efficacy and safety. We will assess whether there has been a reduction in swallowing time, indicating an improvement in swallowing ability.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Sialorrhea
The Sialorrhea Clinical Scale for Parkinson´s Disease assesses sialorrhea; drooling severity, drooling frequency and impact on daily life,. It is a Likert-type 7-item. Each item is ranked on a scale of 0 to 3, with a maximum score of 21. Higher scores correspond to greater disability.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Cough Peak Flow (CPF)
It measures the maximum amount of air exhaled by coughing after taking a deep breath, using the best of three attempts. The A CPF above 270 L/min is associated with an effective cough and good ability to expel secretions. In contrast, a CPF below 160 L/min is considered an ineffective cough, with a higher likelihood of respiratory complications.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow
Cognitive ability to concentrate and inhibit responses- Flanker test
The Flanker test is designed to assess selective attention and inhibitory function, indicating the direction of a central row, flanked by non-target stimuli, which can be congruent (matching the target) or incongruent (opposite to the target). It will be done using an app (C2 Flanker Task) on a tablet with both thumbs at the same time. The reaction time is measured, with higher times indicating less ability to suppress responses to distracting stimuli while focusing on a target stimulus.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Hand tremor
The tremor in left hand will be measured with the app (G-Sensor Logger) for a minute, using a mobile phone secured to the hand.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Static balance- distances
For static balance, a baropodometric platform will be used, and the centre of pressure area (mm), the ellipse area (mm2), and the displacements in the axes of space (mm) will be measured, with eyes open, twice.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Static balance- velocity
For static balance, a baropodometric platform will be used, and the speed (mm/s) of displacements along the axes of space will be measured, with eyes open, twice.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Dynamic balance and functional mobility
The Timed Up and Go test (TUG) represents a measure of global ambulation skills. The patient sits back in a standard chair and, on the command "go", the patient rises, walks 3 meters at a comfortable and safe pace, turns, walks back to the chair and sits down. Time for each attempt is recorded. The best result from 3 attempts will be selected. The longer it takes to complete, the worse the situation becomes, with 12 seconds being the cutoff point for the risk of falling.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Heart Rate Variability (HRV)- frequency domain
Heart Rate Variability (HRV) using Kubios app and H10 polar heart rate monitor chest strap in periods of 5 minutes:
Frequency domain; ratio LF/HF power will be calculated along with normalised LF/HF where baseline values will set to 1; Low frequency (LF, referred to HRV frequency band 0.04-0.15 Hz); High frequency (HF = HRV frequency band 0.15-0.4 Hz); absolute powers of LF, and HF bands (ms2); normalized power (powers of LF and HF bands in normalised units, %)
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Heart Rate Variability (HRV)- time domain
Heart Rate Variability (HRV) using Kubios app and H10 polar heart rate monitor chest strap in periods of 5 minutes:
Time domain: RR (mean values of RR intervals in ms) ; SDNN (Standard deviation of RR intervals); RMSSD (Root mean square of successive RR interval differences, in ms)
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Heart Rate Variability (HRV)- Global measures
Heart Rate Variability (HRV) using Kubios app and H10 polar heart rate monitor chest strap in periods of 5 minutes:
Global measures: Stress Index (SI), square root of Baevsky's stress index; Parasympathetic nervous system (PNS) index; Sympathetic nervous system (SNS) index
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Quality of life in Parkinson´s Disease (PDQ-8)
Quality of life will be assessed using the Parkinson's Disease Questionnaire-8 (PDQ-8), which measures mobility, activities of daily living, emotional well-being, stigma, social support, cognition, communication, and bodily discomfort. Each item is scored on a 0 (= never) to 4 (= always or cannot do at all) range, so the lowest and highest possible scores are 0 and 32, respectively. Greater scores indicate poorer quality of life.
Measured: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 May 2026
- Study start25 May 2026
- Primary completionSep 2026 (estimated)
- Study completionNov 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Transcutaneous Vagal Nerve Stimulation (tVNS)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- stratified by sex and stage on the Hoehn \& Yahr scale
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 46 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Universidade da Coruña
- Sponsor type
- University, hospital or other
- Collaborators
- Parkinson´s Association Galicia-Coruña
- Responsible party
- Principal investigator, Alicia Martínez Rodríguez, Universidade da Coruña
- Investigators
- Alicia Martínez-Rodríguez, Lecrurer, Principal investigator, Universidade da CoruñaOlalla Bello, Lecurer, Principal investigator, Universidade da Coruña
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07588191
- Sponsor's protocol ID
- 2025/295_II
- Acronym
- tVNS_PD
- Status last verified
- May 2026
- First submitted
- 23 Apr 2026
- Last updated
- 7 Aug 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: The IPD that underlie the results included in the publication will be shared on Zenodo, with a description of the codes and the information needed to understand them.
Study at a glance
From the registry record, last updated by the sponsor on 7 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Transcutaneous Stimulation of the Auricular Branch of the Vagus Nerve in Parkinson´s Disease
- ClinicalTrials.gov ID
- NCT07588191
- Acronym / sponsor ID
- tVNS_PD / 2025/295_II
- Keywords
- transcutaneous electrical nerve stimulation, Vagus Nerve, Parkinson Disease, Speech Therapy, Physical Therapy Modalities, Deglutition, Tremor, Posture
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 46 participants (estimated)
- Lead sponsor
- Universidade da CoruñaUniversity, hospital or other
- Collaborators
- Parkinson´s Association Galicia-Coruña
- Study start
- 25 May 2026 (actual)
- Primary completion
- Sep 2026 (estimated)
- Study completion
- Nov 2026 (estimated)
- First posted
- 14 May 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study aims to determine whether electrical stimulation of the ear, when combined with physical and speech therapy, can improve symptoms in subjects diagnosed with Parkinson´s disease, by comparing two different application sites.
Each subject will undergo an initial in-person screening and provide consent before participating in the study.
The main questions to answer are:
- Does transcutaneous electrical nerve stimulation (tVNS) in the ear paired with physical and speech therapy improve speech and voice-related problems, airway protection, salivation, and swallowing?
- Does tVNS paired with physical and speech therapy improve tremor, walking speed, and balance in people with PD?
- Does tVNS paired with physical and speech therapy improve heart rate and heart rate variability in people with PD?
- Do its effects persist at 8 weeks?
Participants will:
Attend 12 rehabilitation sessions over 4 weeks (three per week). During each session, participants received either active or sham tVNS, accompanied by speech therapy (once per week), physical therapy (once per week), or conducted alone (once per week).
Undergo speech, voice, swallowing, respiratory, gait, balance, tremor, heart rate variability, and cognitive testing, as well as questionnaires regarding the quality of life, before and after treatment.
Return for a follow-up visit eight weeks after therapy to check how long the effects last.
Detailed description
Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. Most people with PD will experience dysfunction of the autonomic nervous system (ANS), although the severity of this dysfunction can vary widely, affecting both physical and mental well-being. Symptoms are typically classified as motor or non-motor. Prominent motor symptoms of PD include bradykinesia, rigidity, tremor, and abnormalities in gait, balance, and posture. These symptoms are associated with falls and have a very negative impact on quality of life. In addition, impaired fine motor skills, combined with respiratory and other problems, significantly affect voice, speech, and swallowing, as well as other non-motor disorders, such as neuropsychiatric, sleep, sensory, and digestive disorders.
This study is a double-blind, randomized, controlled trial designed to evaluate the efficacy of transcutaneous auricular vagus nerve stimulation on the motor and non-motor effects of Parkinson´s Disease (PD). Investigators will recruit up to 46 patients. The volunteers will be randomized by sex and the Hoehn and Yahr stage. Clinical information and, specifically, Unified Parkinson's Disease Rating Scale (UPDRS) -III (section III) will be assessed initially.
The primary variable of the study will be voice variables, such as volume, jitter, and shimmer. The remaining dependent variables will be other voice and acustic measures; the presence and severity of dysphagia; the presence and severity of xerostomia and sialorrhea; swallowing efficiency, peak cough flow; the level of tremor; the severity of gait dysfunction; balance; cognitive ability regarding concentration and response inhibition; heart rate and heart rate variability; quality of life in PD; adverse effects; and the degree of effectiveness of blinding.
Over the course of 4 weeks, participants will receive 30-minute stimulation sessions three times weekly, along with physiotherapy and speech therapy once per week. One group will be assigned to stimulation in the cymba concha (where the vagus nerve is placed) and the other (sham) in the earlobe.
Data collection will occur at baseline (T0), post-intervention (T1- 4 weeks), and 8 weeks after finishing the intervention (T2), except for the intensity required to administer electrical stimulation and adverse effects, which will be studied during the whole intervention. Tolerance will be assessed on day 1 of stimulation and on day 12 (4 weeks). Statistical analyses will employ mixed-model approaches to evaluate changes in outcome measures over time and between interventions.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
- Model description
- stratified by sex and stage on the Hoehn \& Yahr scale
| Arm | Type | Receives |
|---|---|---|
| Active tVNS paired with conventional Speech Therapy and Physical Therapy | Active comparator | Device: Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve, Other: Conventional Physical therapy, Other: Conventional Speech TherapyParticipants in this arm will receive transcutaneous electrical stimulation applied to the concha of the left ear for 30 minutes, three times a week, over a 4-week period. This location is known to be innervated by the auricular branch of the vagus nerve. In addition, a speech therapy session and a physical therapy session will be added once a week each, while receiving the electrical stimulation. |
| Sham tVNS paired with Speech Therapy and Physical Therapy | Sham comparator | Other: Conventional Physical therapy, Other: Conventional Speech Therapy, Device: Sham Transcutaneous Electrical Stimulation of Vagus NerveParticipants in this arm will receive the same transcutaneous electrical stimulation as the active group, but applied to the earlobe, a site not innervated by the vagus nerve. The procedure, the appearance of the device, and the parameters are identical to those of the active condition to maintain participant blinding. In addition, a speech therapy session and a physical therapy session will be added once a week each, while receiving the electrical stimulation. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (5 listed)
- Being a member of the Association or be interested in joining;
- Idiopathic PD diagnosis, stages 2-3 according to the Hoehn \& Yahr scale; confirmed by neurologist
- Ability to walk independently for at least 1 minute ant turn 180° without assistance;
- Exhibiting symptoms of hypokinetic dysarthria;
- On stable dopaminergic therapy for at least 1 month prior to the experiment
Key exclusion criteria (8 listed)
- Any contraindication for taVNS (e.g., ear lesions, pacemakers, defibrillators, or other electronic devices)
- Previous vagotomy or previous application of electrical stimulation to the ear or brain, or treatment with high-intensity focused ultrasound (HIFU)
- Voice or speech disorders caused by other medical conditions
- MoCA score below 21
- Psychotic symptoms or hallucinations; a diagnosis of psychiatric illness
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus NerveAlso: tVNS, taVNS, transcutaneous auricular vagus nerve stimulationThe tVNS will be performed at 200 microseconds, with frequencies ranging from 20 to 200 Hz (30 seconds/30 seconds) for 30 minutes, in the area innervated by the auricular branch of the vagus nerve (cymba concha and concha). The individually titrated intensity will be set above the sensory threshold (intense tingling sensation) but below the level of discomfort. | Device | Active tVNS paired with conventional Speech Therapy and Physical Therapy |
| Conventional Physical therapyPhysical therapy delivered to both groups consists of exercises aimed at posture alignment and body coordination, static and dynamic balance improvement, and gait quality. It will be delivered once a week, during a session of electrical stimulation. | Other | Active tVNS paired with conventional Speech Therapy and Physical Therapy, Sham tVNS paired with Speech Therapy and Physical Therapy |
| Conventional Speech TherapyIt will focus on the orofacial muscles, the acquisition of a diaphragmatic-abdominal breathing pattern that integrates breathing with vocal production, voice training with exercises that enhance vocal quality and prosody, articulation exercises to improve speech clarity, and swallowing training. It will be administered once a week, during one of the three electrical stimulation sessions. | Other | Active tVNS paired with conventional Speech Therapy and Physical Therapy, Sham tVNS paired with Speech Therapy and Physical Therapy |
| Sham Transcutaneous Electrical Stimulation of Vagus NerveAlso: Sham location, sham-tVNS, sham- taVNS, sham transcutaneous vagus nerve stimulationThe sham- tVNS will be performed at 200 microseconds, with frequencies ranging from 20 to 200 Hz (30 seconds/30 seconds) for 30 minutes, with electrodes placed on the earlobe, which lacks vagus nerve innervation. The individually titrated intensity will be set above the sensory threshold (intense tingling sensation) but below the level of discomfort. | Device | Sham tVNS paired with Speech Therapy and Physical Therapy |
Primary outcome
Voice intensity
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
The PRAAT software will be used to test the voice twice, when sustaining till 10 seconds the vowel "a" and when reading a text at their usual volume. The intensity (voice volume, measured in decibels) will be recorded.
Voice- Jitter
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
It is derived from the sustaining till 10 seconds the vowel "a". Then, PRAAT software will be used to test the voice, discarding the beginning and the end. The Jitter is defined as the variation in frequency from cycle to cycle, a measure of vocal instability, expressed as a percentage. The higher the percentage, the more irregularities the voice will have.
Voice- Shimmer
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
It is derived from the sustaining till 10 seconds the vowel "a". Then, PRAAT software will be used to test the voice, discarding the beginning and the end. The Shimmer refers to the variation in the amplitude of the sound wave. It is a measure of vocal instability, expressed as a percentage. The higher the percentage, the more irregularities the voice will have.
22 secondary outcomes
Voice fundamental frequency (F0)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Harmonic to Noise Ratio (HNR)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Maximum phonation time (MPT)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Maximum expiratory time during sustained /s/
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Index s/a
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Diadihokinetic rates (DDK)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Self-perceived handicap associated with dysphonia: Voice Handicap Index (VHI-10)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Salivation
Time frame: Baseline (T0), post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Swallowing- dysphagia
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Cookie Swallow Test
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Timed Water Swallow Test (TWST)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Sialorrhea
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Cough Peak Flow (CPF)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow
Cognitive ability to concentrate and inhibit responses- Flanker test
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Hand tremor
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Static balance- distances
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Static balance- velocity
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Dynamic balance and functional mobility
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Heart Rate Variability (HRV)- frequency domain
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Heart Rate Variability (HRV)- time domain
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Heart Rate Variability (HRV)- Global measures
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Quality of life in Parkinson´s Disease (PDQ-8)
Time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Aug 2026.
- Individual participant dataSharing planned: Yes. The IPD that underlie the results included in the publication will be shared on Zenodo, with a description of the codes and the information needed to understand them.
Related trials for Transcutaneous Vagal Nerve Stimulation (tVNS)
Not yet recruiting
Slow-Paced Breathing and Electrical Vagus Nerve Stimulation as Add-on Treatments for Depression
Depression - Major Depressive Disorder
Recruiting
Fatigue in Sjögren's Syndrome: 3 Therapeutic Strategies
Sjogren Syndrome
Not yet recruiting
Effects of Transcutaneous Vagus Nerve Stimulation on Pain and Brain Activity in Healthy Adults
Acute Pain, Pain Perception
Active, not recruiting
Transcutaneous Vagus Nerve Stimulation (tVNS) for Improved Recovery After Exertion.
Post-COVID-19 Syndrome
Recruiting
The Effect of Transcutaneous Vagal Nerve Stimulation (tVNS) on Cerebral Vasospasm Secondary to Aneurysmal Subarachnoid Hemorrhage
Aneurysmal Subarachnoid Hemorrhage, Vasospasm, Cerebral
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Alicia Martínez-Rodríguez, Lecrurer principal investigator
Universidade da Coruña
Olalla Bello, Lecurer principal investigator
Universidade da Coruña
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve, Conventional Physical therapy and Conventional Speech Therapy in people with Transcutaneous Vagal Nerve Stimulation (tVNS) and Parkinson Disease (PD), run by Universidade da Coruña at 1 site in Spain.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 7 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Spain. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Voice intensity (time frame: Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Aug 2026.