Subjective visual vertical and visual dependency in patients with multiple sclerosis

•We identified greater visual dependence in patients with MS compared to controls.•Increased visual dependence in MS is related to increased disability.•The virtual reality SVV paradigm can be used in neurological patients.•Identifying increased visual dependence in MS opens targeted rehabilitation strategies. Spatial orientation is an inherent ability governed by the complex integration of visual, vestibular and proprioceptive inputs. The degree to which an individual relies upon visual cues, as opposed to the vestibular or proprioceptive cues, is termed visual dependence. Although abnormal visual dependence has been documented in other neurological disorders, it is not known whether MS leads to visual dependence, and if so whether this is related to disease progression, clinical disability, or neuro-inflammatory burden in the central nervous system. To evaluate SVV and visual dependence using a novel mobile virtual reality-based system for subjective visual vertical assessment (VIRVEST) and evaluate its relationship with the Expanded Disability Scale Score (EDSS), MS course and clinical findings. The study included 59 patients with MS and 59 controls. Four tests were integrated in VIRVEST system and performed by each patient: a static SVV, dynamic SVV with clockwise and counter-clockwise background stimulus rotation, and SVV in a virtual reality background – a boat floating in the wavy water - to be adjusted vertically. Visual dependence was evaluated as a function of dynamic SVV. Patients with MS manifest larger biases in both static and dynamic SVV than healthy controls (p