RP201 - Utilizing Video Head Impulse Testing (vHIT) in the Diagnosis of Neurological Disorders: Saccadic Abnormalities and Diagnostic Pitfalls

Abstract:
Video head impulse testing (vHIT) is a key tool for assessing vestibulo-ocular reflex (VOR) function. However, interpreting vHIT in patients with neurological disorders can be challenging due to abnormal saccadic movements despite normal VOR gain. This study presents findings from patients with conditions such as vestibular migraine, stroke, acute vestibular syndrome, spinocerebellar ataxias, Friedreich’s ataxia, mitochondrial disorders, CANVAS, and other neurodegenerative disorders, showing how saccadic metrics can improve diagnostic accuracy. Our research demonstrates that integrating vHIT with detailed oculomotor analysis effectively distinguishes between central and peripheral vestibulopathies.

Summary:
Rationale/Purpose
The video head impulse test (vHIT) is widely used to assess vestibulo-ocular reflex (VOR) function, primarily identifying peripheral vestibular deficits. However, in patients with neurological disorders, vHIT interpretation becomes complex due to abnormal saccadic movements despite normal VOR gain. These challenges often lead to diagnostic errors in distinguishing between central and peripheral vestibulopathies. This study aims to investigate how incorporating saccadic metrics in vHIT assessments can improve diagnostic accuracy in patients with various neurological conditions, such as vestibular migraine, stroke, spinocerebellar ataxias, and other neurodegenerative disorders.

Methods
This study involved 120 patients with central neurological disorders, including vestibular migraine, stroke, acute vestibular migraine, spinocerebellar ataxias, Friedreich's ataxia, mitochondrial disorders, CANVAS, and other neurodegenerative disorders. Each patient underwent vHIT testing, and abnormal saccadic eye movements were recorded alongside VOR gain measurements. The study used detailed oculomotor analysis to capture saccadic metrics and assess their impact on vHIT interpretation. Statistical analysis was conducted to evaluate the correlation between the presence of abnormal saccades and the accuracy of vHIT in distinguishing between central and peripheral vestibular causes.

Results & Conclusions
Results showed that in all cases the presence of abnormal saccades (e.g., gaze-evoked nystagmus) impacted the vHIT interpretation. Incorporating saccadic metrics significantly improved the accuracy of diagnosing central vestibular disorders by helping differentiate them from peripheral vestibulopathies. These findings demonstrate the critical role of combining vHIT with detailed oculomotor analysis for accurate neurological diagnoses.

Overall Clarity
The study clearly articulates the limitations of vHIT in neurological patients and presents a compelling case for the inclusion of saccadic metrics in clinical practice.

Importance of Work
This research addresses a critical gap in the clinical application of vHIT in neurological patients. By improving diagnostic accuracy, the findings have the potential to impact clinical practice, improve the education of clinicians on the importance of oculomotor analysis, and inform future research on vestibular testing in neurological populations.

Innovation
The innovation in this study lies in the novel approach of integrating saccadic metrics with vHIT to overcome diagnostic challenges in neurological patients. This methodology provides a more comprehensive diagnostic tool, improving differentiation between central and peripheral vestibular disorders, and is expected to influence both clinical protocols and research methodologies.

Brief Summary of Clinical Takeaways:
The clinical takeaway for this session is that incorporating saccadic metrics into video head impulse testing (vHIT) improves diagnostic accuracy in neurological patients by helping distinguish between central and peripheral vestibular disorders. This approach can optimize patient care by preventing misdiagnoses and ensuring appropriate treatment strategies.