Bedside Video Oculography-Based Test Tracks Loss of Otolith Function

By Marilynn Larkin

April 01, 2021

NEW YORK (Reuters Health) - A novel bedside test using video oculography detected and tracked loss of otolith function in a case-control study.

"Recent advances in video oculography have made it possible to measure vestibulo-ocular function at the bedside," Dr. Amir Kheradmand of Johns Hopkins University School of Medicine in Baltimore told Reuters Health by email. "Using this novel technology, video head impulse testing (vHIT) is now used widely by clinicians to examine semicircular canal function."

"In this study, we introduce video-oculography-based measurement of ocular counter-roll (vOCR) as a new video method for testing otolith function, which is based on measurement of ocular counter-rolling during head tilt," he said. "The main advantage is that it can be performed with a simple bedside maneuver. The use of high-speed video goggles and automated analysis software can provide immediate results during evaluation of patients with dizziness and balance problems."

"In addition," he noted, "vOCR can be combined with vHIT as one battery of tests for assessment of both otolith and canal functions."

As reported in JAMA Otolaryngology-Head and Neck Surgery, the case-control study included 56 individuals (mean age, 53.5; about half, men) with acute (four or more weeks after surgery), subacute (four weeks-six months after surgery), and chronic (more than six months after surgery) unilateral vestibular loss, plus controls.

The mean time of acute unilateral vestibular loss was nine days in the acute group; 61 in the subacute group; and 985 in the chronic group.

The vOCR test showed a reduction on the side of vestibular loss, and the deficit was greater in patients with acute and subacute vestibular loss than in those with chronic loss and controls: acute versus chronic: −1.81 degrees; acute versus controls: −3.18 degrees; subacute versus chronic: −0.63 degrees; subacute versus controls: −2.01 degrees; acute versus subacute: −1.17 degrees; and chronic versus controls: −1.37 degrees.

The asymmetry in vOCR between the side of vestibular loss and the healthy side was significantly higher in patients with acute versus chronic loss (0.28), but there was no significant difference between the acute and subacute groups (0.22) or between the subacute and chronic groups (0.07).

Overall, the vOCR test performance in discriminating between patients with vestibular loss and controls was 0.83 (area under the receiver operating characteristic curve). The best vOCR threshold to detect vestibular loss at the 30-degree tilt was 4.5 degrees, which had 80% sensitivity and 82% specificity.

"The study findings suggest that the deficit in vOCR can change over time," Dr. Kheradmand noted. "It is not yet known whether this change corresponds with improvement of daily functioning and vestibular symptoms. If such a link is found by future studies, vOCR can be used as a noninvasive and quick method for measuring and tracking recovery in patients with vestibular loss."

Dr. Marie Homsi, Director of the Pediatric Vestibular Program at Hassenfeld Children's Hospital at NYU Langone Health in New York City commented in an email to Reuters Health that the test "is a simple head tilt maneuver that can be easily and safely performed at bedside. The operator can easily complete the task by receiving accurate feedback from the VOG goggles to ensure that the tilt maneuver is being appropriately performed and that the recorded numeric values are accurate. This test can be applied across different settings and for most patients."

The study is well-designed, she said, "and includes patients from different stages of compensation, providing information about otolith function at each stage of loss of vestibular function."

"The concern is that a case-control design was adopted with a small sample size, and all patients who were recruited had unilateral vestibular dysfunction following resection of vestibular schwannoma," she said. "Studying vOCR on different pathologies and different tilt angles will generate further information about the application of this test in diagnosing vestibular dysfunction."

SOURCE: JAMA Otolaryngology-Head and Neck Surgery, online March 25, 2021.