Citations

Purpose: Chronic dizziness and imbalance is often difficult to rehabilitate based on the complex set of systems involved. Recently, transcutaneous vagus nerve stimulation (tVNS) has been investigated as a noninvasive means to reduce symptoms associated with vestibular impairment, chronic dizziness, and neurological conditions affecting balance control. The purpose of this integrative review is to examine available data describing therapeutic efficacy and proposed mechanisms of tVNS in adult patients with dizziness and imbalance. Method: PubMed, Europe PMC, and Google Scholar searches were conducted using the following search terms from 1987 to 2024: “vagal nerve stimulat*” OR “vagus nerve stimulat*” OR “transcutaneous vagus nerve stimulat*” OR “tVNS” AND “dizziness,” “vertigo.” Articles were imported for screening and review through Rayyan. Articles discussing the use of tVNS to study metrics related to vestibular and balance function in adult humans were selected for full-text review. Results: Eleven articles were identified as meeting the inclusion criteria and are classified according to the neurotological class studied and level of evidence provided. Available data show that tVNS may benefit patients with dizziness and imbalance based on subjective metrics including quality of life and reduction in dizziness handicap. Less-controlled case study evidence suggests that additional benefit from tVNS may manifest in changes to vestibulo-ocular reflex function. Conclusion: Although tVNS exposure has provided variable degrees of benefit in both subjective (e.g., quality of life) and objective (e.g., changes in vestibulo-ocular reflex function and gait) contexts, the degree to which distinct mechanisms can explain these benefits is unclear.

Abstract Background Vestibular migraine (VM) is one of the common causes of episodic dizziness, but it is underdiagnosed and poorly understood. Previous research suggests that otolith reflex pathway performance is often impaired in this patient group, leading to altered perception of roll plane stimuli. Clinically, this perception can be measured with subjective visual vertical (SVV) testing. Purpose The aim of this study is to compare static SVV performance (absolute mean SVV tilt, variance) in a cohort of patients diagnosed with VM to results obtained from clinically derived normative data. Study Design Retrospective case review. Study Sample Ninety-four consecutive patients between 18 and 65 years of age diagnosed with VM were included in this comparison to clinically derived normative data. Data Collection and Analysis Retrospective chart review was completed. Demographic data, symptom report, and vestibular laboratory results were documented. SVV performance was documented in terms of absolute mean SVV tilt and response variance. Results Abnormal mean SVV tilt was described in 54% (n = 51) of patients with VM. Including abnormal response variance increased those identified with abnormal presentation to 67% (n = 63). Laboratory findings were insignificant for semicircular canal function, but of those with abnormal ocular vestibular myogenic potential results (n = 30), 77% (n = 23) demonstrated both abnormal SVV and utriculo-ocular reflex performance. There were no associations noted for SVV performance and demographic or other self-report variables. Conclusion Absolute mean SVV tilt and response variance are often abnormal in patients diagnosed with VM. These findings support theories suggesting atypical intralabyrinthine integration within the vestibular nuclei and cerebellar nodular pathways.

Objective: The purpose of this study was to provide empirical data describing the relationship between behavioral responses to dynamic visual motion in adults with chronic dizziness symptoms with and without clinically identifiable peripheral vestibular impairment. Design: Prospective, quasi-experimental study including individuals with chronic dizziness symptoms with identified unilateral peripheral vestibular impairment (n=27), and individuals with chronic dizziness symptoms without identified vestibular impairment (n=26). We measured (a) visual perception of verticality in a dynamic background, (b) postural displacement in a dynamic background, (c) eye movement behaviors in various visual contexts, and (d) self-rating degree of anxiety. Results: Status of peripheral vestibular function was not a significant predictor of behavioral responses to visual motion. The data show that the ability to fixate on a visual target was predictive of postural control in a dynamic visual background. Trial-to-trial variability in verticality responses and degree of self-rated anxiety were also associated with postural control. Conclusions: Apart from vestibular function, oculomotor control is important for maintaining control of whole-body motor responses during exposure to a dynamic visual stimulus. Vertical perception precision—not accuracy—may be more important for understanding real-world consequences of visual motion sensitivity. Traditional diagnostic evaluations focusing exclusively on characterizing the peripheral vestibular system may not provide insight into the behaviors associated with visual motion sensitivity.