VISUAL FEEDBACK EXACERBATES MOTOR DYSFUNCTION IN FUNCTIONAL NEUROLOGICAL DISORDER: EVIDENCE FROM VIRTUAL AND AUGMENTED REALITY

Virtual and Augmented Reality are increasingly used in medicine and may offer novel interventions for Functional Neurological Disorder (FND), a common neurological disease resulting from brain abnormal functioning, by targeting mechanisms of impaired motor control. However, evidence for the effect of different modalities on movement in FND is limited. Fifteen FND patients and eighteen healthy controls completed a dual motor-cognitive task across three modalities: Augmented Reality (AR), where participants saw their real arm; Virtual Reality (VR), with a virtual arm; and Virtual Reality Improved (VRI), with artificially enhanced movement. FND participants were slower and produced less smooth movements in AR compared to VR (b = 1.09, z = 8.83, P < .001) and VRI (b = 0.85, z = 6.91, P < .001), a difference that hasn’t been found in healthy controls. Across all modalities, FND participants additionally reduced the number of high-velocity peaks, suggesting more efficient movement adjustments (b = −5.40, z = −9.12, P < .001). Eye tracking showed that FND patients looked more at their body than controls (b = 0.0056, z = 3.31, P < .001), and more at their affected hand than unaffected hand (b = 0.0129, t = -3.44, P > 0.001). Visual feedback of their limb appears to exacerbate motor impairments in FND, likely reinforcing maladaptive self-monitoring. Training reduces corrective sub-movements, particularly in the most challenging AR modality. These findings highlight the therapeutic potential of VR/AR interventions and provide the basis for future studies examining longer protocols and implementation in motor rehabilitation.