Dizziness Due to Visual Stimuli in Patients With Concussion and Other Causes of Dizziness: Examination of Balance Behaviour

Sport-related concussion (SRC) refers to traumatic head injuries caused by direct biomechanical forces to the head, neck or body during physical activity. Due to very heterogeneous clinical patterns in concussed patients including multiple clinical profiles and subtypes, standardised diagnosis for SRC is still in scope of research. Thus, diagnostic procedures are currently based on clinical examination and subjective complaints using questionnaires, while objective assessments supporting a diagnosis for concussed patients are lacking. Only some functional limitations are recorded via objective methods, but no quantification and no diagnosis are possible.

Common questionnaires to assess VID in concussed patients and for vestibular disorders are the visual vertigo analogue scale (VVAS), and the situational vertigo questionnaire (SVQ), though there exist more. The dizziness handicap inventory (DHI) is used to classify the general aspect of dizziness. Other methods to support VID diagnosis have been developed including subjective visual vertical assessment or balance screenings with optokinetic stimulation. Such objective findings are essential for a reliable diagnosis supporting subjective complaints. However, determined parameters and observed pathologies vary among studies and thus, a classification via objective assessments in VID patients is still in scope of research. Nevertheless, symptom assessment is still considered as one of the best and reliable method to support diagnosis and success in treatment.

Outcomes of previously discussed and used questionnaires to assess VID rely on patients' compliance. Subjective evaluations on dizziness are challenging for patients and may therefore diverge from objective measurements. In addition, questionnaires do not explicitly distinguish between vertigo and dizziness. Moreover, self-reported symptoms showed moderate correlation to objective findings. This highlights the importance of realising objective methods such as balance assessments.

Some objective assessments to identify VID, and to discriminate among patient groups and healthy subjects have been introduced. But most of the studies investigating VID examined a broad variety of vestibular disorders, rarely including concussion.

Concerning balance assessment combined with optokinetic stimulation, several studies found significant differences among control groups and patients with vestibular disorders and dizziness, but findings varied across calculated parameters. Overall, mean deviations on sway path tended to be more predictive than lean sway, and significant effects are supposed to be in stimulated planes. Additionally for path length, there exists two quotients representing the balance response ratio between eyes open and eyes closed (Romberg quotient), and the ratio between eyes open and optokinetic stimulation (optokinetic quotient), which both showed significant effects comparing healthy subjects and visual vertigo patients. However, parameters evaluated from velocity were often in favour compared to path length. Furthermore, prolonged exposure to optokinetic stimulation triggered symptoms in patients with visual vestibular mismatch but not in control subjects, supporting the hypotheses of symptom exacerbation by visual motion. Regarding defined triggers for VID, one could assume that triggers are based on an individual level and therefore include various visual motion conditions such as complex, large-field or moving elements in order to conflict one's sensory integration. Given those multidimensional conditions for an assessment, the use of VR environments for this project benefits a broad and flexible range in VID assessment. Regarding the mentioned studies, one could assume that balance evaluation on multiple optokinetic stimuli and comparison to reference values based on healthy subjects has the potential to increase the sensitivity of the balance screening for VID subjects, and in particular concussed patients.

This project aims to generate greater reliability using a more differentiated balance assessment with optokinetic stimulation. Findings are assumed to help identifying potential VID on a more individual basis and support accurate classification.

Inclusion criteria

• Age between 18 and 60 years
• Binocular vision
• Recent concussion/mTBI within 4 weeks to 18 months post-injury for concussed patients
• Diagnosis related to dizziness or VID within 4 weeks to 18 months for non-concussed dizzy patients (including vestibular migraine)
• Signed ICF for included participants or signed general consent for retrospectively included patients if an ICF cannot be obtained.

Exclusion criteria

• BMI greater than 30
• Acute vestibular syndrome lasting at least 24 hours
• Severe non-correctable visual impairment
• Balance issues not dizziness-related, including:

• Neurological conditions (e.g., migraine)
• Orthopaedic conditions (e.g., lower extremity injury)
• Infectious diseases
• Other medical contexts
• Dizziness attributed to prescribed drugs, substance abuse, or mental disorders
• Cognitive impairments compromising task comprehension
• Preceding history of traumatic brain injury in the last 12 months
• History of severe traumatic brain injury with persisting impairments
• Other potentially confounding problems (e.g., psychiatric disease)
• Frequent episodes of rotatory vertigo