Cerebral Palsy (CP), Musculoskeletal Pain
Conditions
Keywords
vagus nerve stimulation, musculoskeletal pain, taVNS, cerebral palsy
Brief summary
This randomized, double-blind, sham-controlled clinical trial will evaluate the safety and efficacy of a 30-day home-based transcutaneous auricular vagus nerve stimulation (taVNS) intervention in adults with cerebral palsy (CP) and chronic musculoskeletal pain. Participants will be randomized to receive either active taVNS targeting the auricular branch of the vagus nerve or sham stimulation delivered to the earlobe. The primary outcomes are changes in musculoskeletal pain severity and pain interference, as well as safety assessed through treatment-emergent adverse events. Exploratory outcomes include health-related quality of life, depression, fatigue, spasticity, systemic inflammatory biomarkers, and blinding success.
Detailed description
Chronic musculoskeletal pain is highly prevalent among adults with cerebral palsy (CP) and represents a major contributor to disability, reduced quality of life, and psychological distress. Pain in CP is often persistent, multifactorial, and inadequately controlled with available pharmacologic and rehabilitative treatments. Emerging evidence suggests that chronic low-grade inflammation, altered autonomic regulation, and disrupted central pain modulation may contribute to pain persistence in this population. The vagus nerve plays a key role in regulating descending inhibitory pain pathways and inflammation via the inflammatory reflex. Reduced vagal tone has been associated with chronic pain and mood disturbances, suggesting that interventions targeting vagal activity may offer therapeutic benefit. Transcutaneous auricular vagus nerve stimulation (taVNS) is a noninvasive neuromodulation technique that activates vagal afferent fibers via the external ear and has demonstrated safety and feasibility across multiple clinical populations. This single-site, randomized, double-blind, sham-controlled clinical trial will enroll adults with CP and chronic musculoskeletal pain. Participants will be randomized in a 1:1 ratio to receive either active taVNS targeting the auricular branch of the vagus nerve or sham stimulation delivered to the earlobe. The intervention will consist of a 30-day home-based stimulation protocol. Outcomes will be assessed at baseline and immediately following the intervention period. The primary outcomes of this study are changes in musculoskeletal pain severity and pain-related interference with daily activities, as well as safety as assessed by treatment-emergent adverse events. Secondary and exploratory outcomes include measures of health-related quality of life, mood, fatigue, spasticity, autonomic function assessed via heart rate variability, and systemic inflammatory biomarkers. Findings from this trial will inform the therapeutic potential of taVNS for chronic pain in adults with CP and support the design of future definitive randomized controlled trials.
Interventions
Stimulation will target the auricular branch of the vagus nerve by applying stimulation to the cymba conchae region of the ear using the tVNS R device (taVNS Technologies, Erlangen, Germany). To achieve adequate stimulation while avoiding unpleasant or painful sensations, the stimulation intensity will be gradually increased in increments of 0.1mA (milliamps) until the subjective pain threshold is reached, and then reduced to a stimulus intensity just below the individuals pain threshold (expected range based on prior studies 1 - 3.2mA). Pulse width will be set at 100μs (microseconds) and frequency will be set at 25Hz (Hertz). Parameters will be set for the duration of the intervention consisting of 4 hours of daily stimulation for a period of 30 days.
Stimulation will target the ear lobe using the tVNS R device (taVNS Technologies, Erlangen, Germany). To achieve adequate stimulation while avoiding unpleasant or painful sensations, the stimulation intensity will be gradually increased in increments of 0.1mA until the subjective pain threshold is reached, and then reduced to a stimulus intensity just below the individuals pain threshold (expected range based on prior studies 1 - 3.2mA). Pulse width will be set at 100μs and frequency will be set at 25Hz. Participants will perform 4 hours of stimulation per day for a period of 30 days. Stimulation will be applied to the ear lobe in order to ensure participant feel the stimulation while avoiding activation of the vagus nerve.
Sponsors
London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Intervention model description
This is a randomized, double-blind, sham-controlled, parallel-group study. Thirty-two adults with cerebral palsy and chronic musculoskeletal pain will be randomized in a 1:1 ratio to receive either active transcutaneous auricular vagus nerve stimulation (taVNS) or sham taVNS. Following a baseline visit that includes eligibility confirmation, outcome assessments, and device training, participants will complete a 30-day home-based intervention during which they will use the assigned stimulation device for 4 hours per day. Outcomes will be assessed at baseline and immediately following the 30-day intervention period. Participants, investigators, care providers, and outcome assessors will remain blinded to treatment allocation throughout the study.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Diagnosis of cerebral palsy * Age ≥18 years * Chronic musculoskeletal pain present for ≥1 year * Moderate or greater pain severity (≥4/10 on Numeric Pain Rating Scale) * Stable pain and/or anti-inflammatory medication dosing for ≥6 weeks
Exclusion criteria
* Cardiovascular disease * Pacemaker or implanted electrical device * Cerebral shunt * Pregnancy or intent to become pregnant * Current infection or open wounds at electrode sites
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Musculoskeletal Pain Assessed by the Brief Pain Inventory | Baseline and Day 30 | Musculoskeletal pain severity and pain interference will be assessed using the Brief Pain Inventory (BPI). The BPI pain severity subscale evaluates pain intensity using four 0-10 numeric rating scale items assessing worst, least, average, and current pain. A composite pain severity score will be calculated as the mean of these four items, in accordance with IMMPACT recommendations. Pain interference will be assessed using the BPI interference subscale, which evaluates the extent to which pain interferes with general activity, mood, walking ability, normal work, relationships, sleep, and enjoyment of life using 0-10 numeric rating scales. Higher scores indicate greater pain severity or interference. Assessments will be conducted by trained outcome assessors blinded to group allocation. |
| Change in Musculoskeletal Pain Assessed by the Numeric Pain Rating Scale | Baseline and Day 30 | Musculoskeletal pain severity will also be assessed using the Numeric Pain Rating Scale (NPRS), a simple and widely used self-report measure of pain intensity. Participants will rate their average pain intensity on an 11-point numeric rating scale ranging from 0 (no pain) to 10 (worst imaginable pain). The NPRS will serve as a complementary, standardized measure of pain intensity to enhance the robustness and interpretability of pain assessment. |
| Incidence of Treatment-Emergent Adverse Events During Intervention | 30 days | All treatment-emergent adverse events occurring during the intervention period will be recorded through weekly phone calls and/or study visits. Adverse events will be summarized by type, frequency, severity, and relationship to the study intervention. The number and proportion of participants experiencing at least one adverse event will be compared between the active taVNS and sham taVNS groups. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Health-Related Quality of Life (EQ-5D-5L) | Baseline and Day 30 | Health-related quality of life will be assessed using the EuroQol 5-Dimension 5-Level questionnaire (EQ-5D-5L), a validated self-report measure of health status. The EQ-5D-5L assesses five domains: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, each rated across five levels of severity. Change in health-related quality of life from baseline to the end of the 30-day intervention period will be compared between the active taVNS and sham taVNS groups. Higher index values and visual analogue scale scores indicate better health status. |
| Change in Depressive Symptoms assessed by the Patient Health Questionnaire-9 | Baseline and Day 30 | Depressive symptoms will be assessed using the Patient Health Questionnaire-9 (PHQ-9), a validated self-report questionnaire that measures the severity of depressive symptoms experienced over the past two weeks. Total scores range from 0 to 27, with higher scores indicating greater depressive symptom severity. Change in PHQ-9 scores from baseline to the end of the 30-day intervention period will be compared between the active taVNS and sham taVNS groups. |
| Change in Depressive Symptoms assessed by the Hamilton Depression Rating Scale | Baseline and Day 30 | Depressive symptoms will be assessed using the Hamilton Depression Rating Scale (HAM-D), a clinician-administered measure of depression severity. The HAM-D will be completed by a trained assessor blinded to group allocation. Higher scores indicate greater depressive symptom severity. Change in HAM-D scores from baseline to the end of the 30-day intervention period will be compared between the active taVNS and sham taVNS groups. |
| Change in Fatigue Severity and Impact assessed by the Fatigue Impact and Severity Self-Assessment | Baseline and Day 30 | Fatigue will be assessed using the Fatigue Impact and Severity Self-Assessment (FISSA), a self-report questionnaire developed for individuals with cerebral palsy. The FISSA includes 31 items assessing fatigue severity, the impact of fatigue on daily activities, and fatigue management behaviors. Items are rated on a five-point Likert scale, with higher scores indicating greater fatigue severity and impact. Change in fatigue from baseline to the end of the 30-day intervention period will be evaluated using the FISSA total score and compared between the active taVNS and sham taVNS groups. |
| Change in Spasticity Severity assessed by the Numeric Rating Scale | Baseline and Day 30 | Spasticity will be assessed using a patient-reported Numeric Rating Scale (NRS). Participants will rate the severity of their spasticity over the past 24 hours on an 11-point scale ranging from 0 (no spasticity) to 10 (worst possible spasticity). Higher scores indicate greater spasticity severity. Change in spasticity severity from baseline to the end of the 30-day intervention period will be compared between the active taVNS and sham taVNS groups. |
| Change in Circulating C-Reactive Protein | Baseline and Day 30 | Plasma concentrations of C-reactive protein (CRP) will be measured from fasting blood samples collected at baseline and at the end of the intervention. Concentrations will be reported in milligrams per liter (mg/L), with higher values indicating greater systemic inflammation. Change values will be calculated as post-intervention values minus baseline values and summarized descriptively between the active taVNS and sham taVNS groups. |
| Change in Circulating Interleukin-1 Beta | Baseline and Day 30 | Plasma concentrations of interleukin-1 beta (IL-1β) will be measured from fasting blood samples collected at baseline and at the end of the intervention. Concentrations will be reported in picograms per milliliter (pg/mL), with higher values indicating greater pro-inflammatory activity. Change values will be calculated as post-intervention values minus baseline values and summarized descriptively between the active taVNS and sham taVNS groups. |
| Change in Circulating Interleukin-6 | Baseline and Day 30 | Plasma concentrations of interleukin-6 (IL-6) will be measured from fasting blood samples collected at baseline and at the end of the intervention. Concentrations will be reported in picograms per milliliter (pg/mL), with higher values indicating greater pro-inflammatory activity. Change values will be calculated as post-intervention values minus baseline values and summarized descriptively between the active taVNS and sham taVNS groups. |
| Change in Circulating Interferon Gamma | Baseline and Day 30 | Plasma concentrations of interferon gamma (IFN-γ) will be measured from fasting blood samples collected at baseline and at the end of the intervention. Concentrations will be reported in picograms per milliliter (pg/mL), with higher values indicating greater pro-inflammatory activity. Change values will be calculated as post-intervention values minus baseline values and summarized descriptively between the active taVNS and sham taVNS groups. |
| Change in Circulating Tumor Necrosis Factor Alpha | Baseline and Day 30 | Plasma concentrations of tumor necrosis factor alpha (TNF-α) will be measured from fasting blood samples collected at baseline and at the end of the intervention. Concentrations will be reported in picograms per milliliter (pg/mL), with higher values indicating greater pro-inflammatory activity. Change values will be calculated as post-intervention values minus baseline values and summarized descriptively between the active taVNS and sham taVNS groups. |
| Success of Participant and Investigator Blinding | Day 30 | Blinding success will be assessed after completion of the intervention by asking participants and investigators to indicate which treatment group they believe the participant was assigned to (active taVNS or sham taVNS). Blinding effectiveness will be quantified using the James Blinding Index, calculated separately for participants and investigators. Blinding outcomes will be summarized descriptively. |
Countries
Canada
Contacts
CONTACTDavid J Allison, PhD.
CONTACTJoy Jiang
Outcome results
None listed