Effects of Transcutaneous Stimulation of the Auricular Branch of the Vagus Nerve in Parkinson´s Disease
Trial Snapshot
- Phase
- Not Applicable
- Status
- Active, not recruiting
- Sponsor
- Universidade da Coruña
- Enrollment
- 46
- Locations
- 1
- Primary Endpoint
- Voice intensity
Study Overview
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.
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
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Treatment
- Masking
- Double (Participant, Outcomes Assessor)
Eligibility Criteria
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •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
Exclusion Criteria
- •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
Arms & Interventions
Active tVNS paired with conventional Speech Therapy and Physical Therapy
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.
Intervention: Conventional Speech Therapy (Other)
Sham tVNS paired with Speech Therapy and Physical Therapy
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.
Intervention: Conventional Physical therapy (Other)
Sham tVNS paired with Speech Therapy and Physical Therapy
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.
Intervention: Conventional Speech Therapy (Other)
Active tVNS paired with conventional Speech Therapy and Physical Therapy
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.
Intervention: Transcutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve (Device)
Active tVNS paired with conventional Speech Therapy and Physical Therapy
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.
Intervention: Conventional Physical therapy (Other)
Sham tVNS paired with Speech Therapy and Physical Therapy
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.
Intervention: Sham Transcutaneous Electrical Stimulation of Vagus Nerve (Device)
Outcomes
Primary Outcomes
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.
Secondary Outcomes
- Voice fundamental frequency (F0)(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Swallowing- dysphagia(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))
- Diadihokinetic rates (DDK)(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Timed Water Swallow Test (TWST)(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)(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Salivation(Baseline (T0), post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Cookie Swallow Test(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Sialorrhea(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Cough Peak Flow (CPF)(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow)
- Heart Rate Variability (HRV)- Global measures(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Cognitive ability to concentrate and inhibit responses- Flanker test(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Hand tremor(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Static balance- distances(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Static balance- velocity(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Dynamic balance and functional mobility(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Heart Rate Variability (HRV)- frequency domain(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
- Heart Rate Variability (HRV)- time domain(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)(Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2))
Investigators
Alicia Martínez Rodríguez
Lecturer; Faculty of Physical Therapy. Researcher; Psychosocial Intervention and Functional Rehabilitation Group
Universidade da Coruña