Transcutaneous Vagal Nerve Stimulation (tVNS), Parkinson Disease (PD)
Conditions
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
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.
Interventions
DEVICETranscutaneous Electrical Nerve Stimulation (TENS) of Vagus Nerve
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.
OTHERConventional Physical therapy
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.
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.
DEVICESham Transcutaneous Electrical Stimulation of Vagus Nerve
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.
Sponsors
Universidade da Coruña
Parkinson´s Association Galicia-Coruña
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Intervention model description
stratified by sex and stage on the Hoehn & Yahr scale
Eligibility
Sex/Gender
ALL
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Voice intensity | 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 | 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 | 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
| Measure | Time frame | Description |
|---|---|---|
| Voice fundamental frequency (F0) | 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 fundamental frequency (F0) is the oscillation originating from the vocal folds. It will be recorded in Hz. |
| Harmonic to Noise Ratio (HNR) | 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 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. |
| Maximum phonation time (MPT) | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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/. |
| Maximum expiratory time during sustained /s/ | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Index s/a | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Diadihokinetic rates (DDK) | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| 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) | 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. |
| Salivation | Baseline (T0), post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Swallowing- dysphagia | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Cookie Swallow Test | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | Time will be measured (velocity), swallow security and efficacy, checking for any residue after swallowing. |
| Timed Water Swallow Test (TWST) | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Sialorrhea | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Cough Peak Flow (CPF) | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow | 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. |
| 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) | 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. |
| Hand tremor | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Static balance- distances | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Static balance- velocity | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| Dynamic balance and functional mobility | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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. |
| 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) 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, %) |
| Heart Rate Variability (HRV)- time domain | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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) |
| Heart Rate Variability (HRV)- Global measures | Baseline (T0), Post-intervention (T1, 4 weeks), along with an 8-week post-trial follow-up (T2) | 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 |
| 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) | 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. |
Countries
Spain
Contacts
CONTACTAlicia Martínez-Rodríguez alicia.martinez@udc.es, Lecturer
CONTACTOlalla Bello, Lecturer
PRINCIPAL_INVESTIGATORAlicia Martínez-Rodríguez, Lecrurer
Universidade da Coruña
PRINCIPAL_INVESTIGATOROlalla Bello, Lecurer
Universidade da Coruña
Outcome results
None listed