Letter: Vestibular/Ocular Motor Screening as a Novel Test of Cognition at Altitude

Dear Editor,

Altitude-related illness affects multiple organ systems, with some manifestations—particularly neurological—being more insidious and difficult to detect. Hypoxia, a state in which the body’s tissues lack sufficient oxygen supply, is associated with altitude and well known to have negative effects on multiple domains of cognitive ability (Wang, Cui and Ji, 2022). Human exposure to hypoxic environments at high altitude poses a risk of cognitive impairment, making it important for clinicians to be aware of fast, reliable, and accurate methods of assessing cognitive changes in these environments (Bliemsrieder et al., 2022; Fan et al., 2024; Wang, Cui and Ji, 2022). Current nomenclature typically categorizes high-altitude cerebral pathology based on clinical symptomatology (e.g., acute mountain sickness progressing to high-altitude cerebral edema). However, objective assessment of cognitive impairment may offer a more reliable and earlier marker of neurological dysfunction at altitude, especially in operational settings where deficits in executive function or judgment may result in significant morbidity. Three recent reviews found that well over 100 different neuropsychological tests have been used to study cognitive impairment associated with altitude or hypoxia (Bliemsrieder et al., 2022; Fan et al., 2024; Post et al., 2023). One notable absence from these lists was the Vestibular/Ocular Motor Screening (VOMS) test.

The VOMS test was developed as a rapid concussion assessment tool for ambulatory patients that can be administered in less than 10 minutes without advanced technology (Mucha et al., 2014). The test assesses five domains of functioning: smooth pursuits, horizontal and vertical saccades, convergence, horizontal vestibular ocular reflex, and visual motion sensitivity (Mucha et al., 2014). Before and after each domain assessment, patients provide a symptom severity rating from 0 (none) to 10 (severe) for headache, dizziness, nausea, and fogginess (Mucha et al., 2014). It offers rapid administration, strong internal consistency, and minimal equipment requirements, making it an ideal and portable tool for climbers, expedition teams, and others operating in hypoxic conditions and at risk for cognitive impairment. Incorporating VOMS into altitude field research could provide a rapid, low-burden measure of hypoxia-related cognitive change that complements symptom-based scales like the Lake Louise Questionnaire Score. Moreover, given that the VOMS test is performance-based rather than questionnaire-based, it may be less susceptible to practice effects, potentially increasing its reliability. Pilot studies should evaluate feasibility, reliability, and correlation of VOMS results with other altitude-related illness scores and physiological markers such as SpO₂, while larger prospective studies should assess whether early VOMS changes predict the onset or severity of altitude illness.