RP306 - Subjective Visual Vertical in Patients with Post-Concussion Syndrome

Abstract:
Concussion, a common form of mild traumatic brain injury is often accompanied by dizziness and balance difficulties. The purpose of this study was to evaluate balance through perception of verticality on the subjective visual vertical (SVV) test in patients with post-concussion syndrome (PCS). SVV assesses verticality via sensory input from the semicircular canals and the otolith organs, making it a reliable measure of structures that are crucial for balance. This study was a retrospective chart review of 470 PCS patients who completed the SVV test during their post-concussion vestibular evaluation.

Summary:
Concussion is the most common type of mild traumatic brain injury (Tator 2013). When not diagnosed and managed properly concussion can have severe consequences. Common symptoms of concussion include headache, changes in vision, dizziness, and balance difficulties. While vision is routinely assessed in the evaluation of patients with post-concussion syndrome (PCS) through exams such as near point convergence, eye tracking, and other bedside tests, balance is rarely assessed thoroughly. Dizziness is the second most common symptom of concussion and studies have shown otolithic function is often impaired following a sustained concussion (Gianoli 2022). Subjective visual vertical (SVV), a test of verticality, assesses otolithic function, and is a valuable assessment within the vestibular test battery. Previous research found that SVV scores were abnormal in over 50% of patients with migraine, a disorder of the central vestibular system (Bogle et al., 2022). This study aimed to determine if SVV scores were abnormal in patients with (PCS).

This study was a retrospective chart review of 470 PCS patients who completed SVV testing during their post-concussion vestibular evaluation at the Mayo Clinic in Arizona. SVV testing was previously completed using the I-Portal Neuro-Otologic Test Center (Neurolign Technologies Inc, Toronto, ON). Each patient completed the test while seated within an enclosure. A red laser line appeared approximately 19” from the patient. Each patient was instructed to use the buttons on their handgrip to rotate the line left or right until it was straight up and down like the number one. The line set between +/- 25 degrees. Once the patient completed the task they were presented with another line. Each patient repeated this task 10 times.

ANOVA were used for within group and control group comparisons. Preliminary data from 30 patients with PCS revealed mean SVV tilt was 1.69 (SD: 1.44; Range: 0.05-5.87). 56.67% (n = 17) of patients demonstrated an abnormal SVV tilt in one or both directions when compared to individuals with normal SVV scores. SVV variance was abnormal in one or both directions in 63% (n=19) of patients. Findings for SVV mean [F(1, 51) = 6.59, P = .01] and variance [F(1, 51) = 4.79, P = .033] were statistically significant. The complete dataset of 470 patients will be analyzed prior to presentation.

Significant findings from preliminary data suggest SVV testing is abnormal in over half of all PCS patients. This finding further suggests integration of otolithic information may be impaired and should be evaluated as part of the post-concussion clinical assessment.

Brief Summary of Clinical Takeaways:
The clinical takeaway for this session is to understand the utility of including an assessment of otolithic function via perception of verticality in the vestibular test battery of patients with post-concussion syndrome.