Exploring Mild Electrical Vestibular Stimulation as a New Treatment for Dizziness and Migraine Symptoms

Vestibular migraine (VM) is a neurological disorder in which recurrent vestibular symptoms such as vertigo, dizziness, and imbalance occur in association with migraine features. VM can produce persistent motion sensitivity, activity restriction, and functional impairment, and many individuals report incomplete relief of dizziness or imbalance with current pharmacologic strategies. Proposed mechanisms implicate altered multisensory integration across vestibular and migraine-related nociceptive networks, including abnormal brainstem and thalamocortical processing, trigeminal vestibular interactions, neuropeptide mediated neuroinflammation, cortical spreading depression, and central sensitization. These features motivate evaluation of non drug neuromodulation approaches that target vestibular pathway excitability and integration.

Electrical vestibular stimulation (EVS) is a non invasive neuromodulation technique that applies low amplitude electrical current through surface electrodes positioned over the mastoid and upper cervical region to modulate vestibular afferent activity and downstream central vestibular processing. Stochastic "noisy" wideband waveforms can provide continuous vestibular afferent input while remaining below thresholds for overt vestibular reflexes when delivered at subthreshold intensities. Prior balance focused studies have delivered repeated subthreshold stochastic EVS without serious adverse events, supporting evaluation of EVS as a portable and scalable intervention for vestibular conditions. This study is designed as a pilot randomized sham controlled trial to evaluate the feasibility safety and tolerability of repeated EVS delivery in adults with a confirmed clinical diagnosis of VM and to generate preliminary estimates of symptom and functional change to inform the design of a future fully powered randomized controlled trial.

Approximately 50 adults with VM will be recruited through the Calgary Headache Assessment and Management Program and affiliated clinics. Following informed consent and completion of baseline assessments participants will be randomized in a one to one ratio to receive either active EVS or sham EVS using a pre specified allocation schedule. Where feasible randomization will be stratified by sex to promote balance between groups given known sex differences in VM prevalence and symptom expression. The study will use a quadruple masking such that participants, care providers administering stimulation, investigators, and outcome assessors will remain blinded to group assignment throughout the study. Allocation concealment will be maintained by separating roles between personnel responsible for intervention delivery and those conducting outcome assessments. Procedures for unblinding will be after the data has been cleaned and groups need to be separated for comparisons.

Participants will attend six stimulation sessions scheduled across a two week intervention period. Stimulation will be delivered while seated using a wideband noisy waveform at a subthreshold intensity intended to avoid overt vestibular sensations while providing continuous vestibular afferent input. Each visit will include two 20 minute stimulation bouts separated by a 5 minute rest period. Standardized electrode placement skin preparation and impedance checks will be performed at each visit to ensure consistency across sessions. Participants will be allowed to read, rest, or use personal electronic devices during stimulation. Investigators will document session timing adherence and any deviations from the protocol as well as participant reported sensations during and after stimulation.

Participants assigned to the sham condition will undergo identical electrode placement and session structure as the active group. At the beginning of each stimulation bout the device will briefly ramp to mimic cutaneous sensation associated with stimulation onset and will then deliver zero current for the remainder of the bout while maintaining device indicators. This approach preserves participant expectations, staff interaction, and visit structure while withholding therapeutic vestibular stimulation. Study personnel will follow identical scripted procedures and monitoring protocols for both groups to support masking integrity.

Safety and tolerability will be monitored throughout the study period. Investigators will document the onset, duration, severity, and perceived relatedness of all reported events. Criteria for pausing or discontinuing stimulation during a session will be applied if participants experience concerning symptoms. Adverse events will be summarized by frequency severity and relatedness to inform safety characterization and protocol refinement.

Study assessments will be conducted at baseline immediately following completion of the two week intervention period and approximately one month after the final stimulation session. At each assessment, visit participants will complete validated patient reported measures capturing vestibular migraine related symptom impact, migraine related disability dizziness, related functional burden balance confidence, and motion sensitivity susceptibility. Structured symptom provocation procedures relevant to visually and vestibular triggered symptoms will also be completed to characterize changes in symptom sensitivity over time. Objective evaluation of postural control and functional gait will be performed using wearable inertial measurement units (IMUs). IMUs placed on the head trunk and feet will capture kinematic data during quiet standing performed under systematically varied sensory conditions and during standardized functional mobility tasks. These measures will be complemented by computerized dynamic posturography to quantify sensory integration during stance. Standardized task instructions, sensor placement, and trial timing will be used across visits to support consistency and data quality.

To capture day to day variability typical of vestibular migraine and to evaluate the feasibility of longitudinal symptom monitoring participants will complete daily symptom diaries for 30 days before and 30 days after the two week stimulation period. Diaries will record vestibular episode characteristics migraine features perceived symptom severity sleep and medication use. Completion rates and patterns of missing data will be tracked to inform feasibility and to guide protocol optimization for future trials. Among participants who menstruate daily tracking of menstrual bleeding will be included to support exploratory evaluation of symptom patterning.

The primary focus of this pilot trial is feasibility and tolerability, including recruitment and retention adherence to the six session intervention and acceptability of the intervention and assessments. Clinical and functional outcomes will be analyzed using longitudinal approaches appropriate for repeated measures to estimate the direction and variability of change over time between stimulation and sham groups. Effect sizes and confidence intervals will be reported rather than definitive hypothesis testing to support sample size estimation and design refinement for a future definitive randomized controlled trial.

• Change in Dizziness Handicap Inventory (DHI) score [Time frame: Baseline, immediately post intervention, and one month post intervention]
• Change in Activities specific Balance Confidence (ABC) scale score [Time frame: Baseline, immediately post intervention, and one month post intervention]
• Change in Migraine Disability Assessment (MIDAS) scores [Time frame: Baseline and one month post intervention]
• Change in Motion Sickness Susceptibility Questionnaire (MSSQ) scores [Time frame: Baseline and one month post intervention]
• Change in Vestibular Ocular Motor Screening (VOMS) symptom provocation scores [Time frame: Baseline and immediately post intervention]
• Change in modified Motion Sensitivity Test (mMST) score [Time frame: Baseline and immediately post intervention]
• Change in IMU derived postural sway metrics during standing balance tests [Time frame: Baseline, immediately post intervention, and one month post intervention]
• Change in gait performance during 25-foot walking test [Time frame: Baseline, immediately post intervention, and one month post intervention]
• Change in gait performance on Timed Up and Go (TUG) [Time frame: Baseline, immediately post intervention, and one month post intervention]
• Change in Sensory Organization Test (SOT) equilibrium and sensory ratios [Time frame: Baseline, immediately post intervention, and one month post intervention]