1. Measuring optokinetic after-nystagmus: potential for detecting patients with signs of visual dependence following concussion
- Author
-
Fausto Romano, Dominik Straumann, Katharine Keller, Nina Feddermann-Demont, Giovanni Bertolini, Antonella Palla, University of Zurich, and Bertolini, Giovanni
- Subjects
Adult ,medicine.medical_specialty ,Visual perception ,Neurology ,Self-motion perception ,Adolescent ,Clinical Neurology ,Sensory system ,610 Medicine & health ,Audiology ,Nystagmus, Pathologic ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Nystagmus, Physiologic ,Concussion ,Psychophysics ,Medicine ,Animals ,Humans ,10064 Neuroscience Center Zurich ,Sensory cue ,Brain Concussion ,Velocity storage ,Retrospective Studies ,Vestibular system ,Original Communication ,Vestibulo-ocular reflex ,business.industry ,030229 sport sciences ,Optokinetic reflex ,medicine.disease ,Macaca mulatta ,10040 Clinic for Neurology ,2728 Neurology (clinical) ,10076 Center for Integrative Human Physiology ,2808 Neurology ,Female ,Neurology (clinical) ,Vestibule, Labyrinth ,Vestibulo–ocular reflex ,business ,030217 neurology & neurosurgery ,Human - Abstract
Concussed patients with chronic symptoms commonly report dizziness during exposure to environments with complex visual stimuli (e.g. supermarket aisles, busy crossroads). Such visual induced dizziness is well-known in patients with vestibular deficits, in whom it indicates an overreliance on visual cues in sensory integration. Considering that optokinetic after-nystagmus (OKAN) reflects the response of the central network integrating visual and vestibular self-motion signals (velocity storage network), we investigated OKAN in 71 patients [17 (23.9%) females, 30.36 ± 9.05 years old] who suffered from persistent symptoms after a concussion and presented clinical signs suggesting visual dependence. Data were retrospectively compared with 21 healthy individuals [13 (61.9%) females, 26.29 ± 10.00 years old]. The median values of the slow cumulative eye position and of the time constant of OKAN were significantly higher in patients than in healthy individuals (slow cumulative eye position: 124.15 ± 55.61° in patients and 77.87 ± 45.63° in healthy individuals—p = 0.012; time constant: 25.17 ± 10.27 s in patients and 13.95 ± 4.92 s in healthy individuals—p = 0.003). The receiving operating curve (ROC) estimated on the time constant had an overall area under the curve of 0.73. Analysis of the ROC suggests that a test measuring the OKAN time constant could obtain a sensitivity of 0.73 and specificity of 0.72 in determining the origin of the visual-related disturbances in those patients (threshold 16.6 s). In a subset of 43 patients who also performed the Sensory Organization Test (SOT), the proposed OKAN test was twice as sensitive as the SOT. This study suggests that concussed patients with persisting visual symptoms may have an underlying impairment of the velocity storage mechanism and that measuring the OKAN time constant can objectify such impairment.
- Published
- 2021