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

Area of Science:

• Neuroscience
• Ophthalmology
• Vestibular System

Background:

• Subjective visual vertical (SVV) assessment is crucial for evaluating spatial orientation.
• Neck braces (NB) are sometimes used to stabilize the head during SVV testing, aiming to minimize head tilt and ocular torsion.
• The potential influence of somatosensory feedback from the neck on SVV perception remains an area of interest.

Purpose of the Study:

• To investigate the impact of somatosensory inputs, specifically from a neck brace, on the subjective visual vertical (SVV) in healthy volunteers.
• To determine if head fixation using a neck brace affects the accuracy of SVV measurements.

Main Methods:

• Thirty healthy participants underwent static and dynamic SVV testing.
• Measurements were recorded both with and without the application of a neck brace.
• Each condition (with and without NB) included six static and six dynamic SVV trials.

Main Results:

• No statistically significant differences were observed in static or dynamic SVV measurements between conditions with and without the neck brace.
• Mean static SVV values were -0.075º±1.15º without NB and -0.372º±1.21º with NB.
• Dynamic SVV showed minor variations (clockwise: 1.73º±2.31º without NB vs. 1.53º±1.80º with NB; counterclockwise: -1.50º±2.44º without NB vs. -1.11º±2.46º with NB) that were not statistically significant.

Conclusions:

• The application of a neck brace does not significantly alter the subjective visual vertical perception in healthy individuals.
• Despite the presence of numerous sensory receptors in the neck, the afferent input generated by a neck brace is insufficient to modify visual verticality perception.
• These findings indicate that neck proprioception has a limited role in the perception of visual verticality in the absence of head tilt.