Effects of Transcutaneous Vagus Nerve Stimulation in Parkinson´s Disease

NCT07588191 | Recruiting DMC

• 1 other identifier: 2025/295_II
• Study Type: interventional
• Target: 46
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Transcutaneous Vagal Nerve Stimulation (tVNS); Parkinson Disease (PD)

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

Outcome Measures

Primary Outcomes (3)

• 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.

  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.

  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.

  Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)

Secondary Outcomes (22)

• Voice fundamental frequency (F0)

  Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)

• Harmonic to Noise Ratio (HNR)

  Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)

• Maximum phonation time (MPT)

  Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)

• Maximum expiratory time during sustained /s/

  Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)

• Index s/a

  Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)

Other Outcomes (4)

• Effectiveness of blinding

  Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2)

• Adverse effects

  All days of intervention (up to 4 weeks)

• Tolerance to auricular TENS

  Baseline and week-4

Study Arms (2)

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.

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.

Other: Conventional Physical therapy; Other: Conventional Speech Therapy; Device: Sham Transcutaneous Electrical Stimulation of Vagus Nerve

Interventions

Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve DEVICE

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.

Also known as: tVNS, taVNS, transcutaneous auricular vagus nerve stimulation

Active tVNS paired with conventional Speech Therapy and Physical Therapy

Conventional Physical therapy OTHER

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.

Active tVNS paired with conventional Speech Therapy and Physical Therapy; Sham tVNS paired with Speech Therapy and Physical Therapy

Conventional Speech Therapy OTHER

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.

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 Nerve DEVICE

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.

Also known as: Sham location, sham-tVNS, sham- taVNS, sham transcutaneous vagus nerve stimulation

Sham tVNS paired with Speech Therapy and Physical Therapy

Eligibility Criteria

• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Universidade da Coruña: lead
• Parkinson´s Association Galicia-Coruña: collaborator

Study Sites (1)

Association of Parkinson´s Disease Galicia- Coruña

A Coruña, 15008, Spain

RECRUITING

MeSH Terms

Conditions

Parkinson Disease; Communication Disorders; Tremor; Cough; Sialorrhea; Xerostomia; Voice Disorders

Interventions

Transcutaneous Electric Nerve Stimulation

Condition Hierarchy (Ancestors)

Parkinsonian Disorders; Basal Ganglia Diseases; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Movement Disorders; Synucleinopathies; Neurodegenerative Diseases; Neurobehavioral Manifestations; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Neurodevelopmental Disorders; Mental Disorders; Dyskinesias; Respiration Disorders; Respiratory Tract Diseases; Signs and Symptoms, Respiratory; Salivary Gland Diseases; Mouth Diseases; Stomatognathic Diseases; Laryngeal Diseases; Otorhinolaryngologic Diseases

Intervention Hierarchy (Ancestors)

Electric Stimulation Therapy; Therapeutics; Physical Therapy Modalities; Rehabilitation; Analgesia; Anesthesia and Analgesia

Study Officials

• Alicia Martínez-Rodríguez, Lecrurer

  Universidade da Coruña

  PRINCIPAL INVESTIGATOR

• Olalla Bello, Lecurer

  Universidade da Coruña

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Alicia Martínez-Rodríguez alicia.martinez@udc.es, Lecturer

CONTACT

+34 881015851; alicia.martinez@udc.es

Olalla Bello, Lecturer

CONTACT

+34 881015852; olalla.bello@udc.es

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Lecturer; Faculty of Physical Therapy. Researcher; Psychosocial Intervention and Functional Rehabilitation Group

Model Details: stratified by sex and stage on the Hoehn \& Yahr scale

Study Record Dates

• First Submitted: April 23, 2026
• First Posted: May 14, 2026
• Study Start: May 1, 2026
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): November 1, 2026
• Last Updated: May 19, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: SAP
• Time Frame: Beginning 1 year after publication and with no ending while Zenodo keep the data
• Access Criteria: The results will be included in a document that will be shared on Zenodo with all investigators interested in them via direct access.

Locations

ES (1)