The use of a neck brace does not influence visual vertical perception

Abstract

Subjective visual vertical (SVV) evaluates the individual's capacity to determine the vertical orientation. Using a neck brace (NB) allow volunteers' heads fixation to reduce cephalic tilt during the exam, preventing compensatory ocular torsion and erroneous influence on SVV result. Objective: To analyze the influence of somatosensory inputs caused by a NB on the SVV. Method: Thirty healthy volunteers performed static and dynamic SVV: six measures with and six without the NB. Results: The mean values for static SVV were -0.075°±1.15° without NB and -0.372°±1.21° with NB. For dynamic SVV in clockwise direction were 1.73°±2.31° without NB and 1.53°±1.80° with NB. For dynamic SVV in counterclockwise direction was -1.50°±2.44° without NB and -1.11°±2.46° with NB. Differences between measurements with and without the NB were not statistically significant. Conclusion: Although the neck has many sensory receptors, the use of a NB does not provide sufficient afferent input to change healthy subjects' perception of visual verticality.