Different Types of Mastoid Process Vibrations Affect Dynamic Margin of Stability Differently.

Area of Science:

• Neuroscience
• Biomechanics
• Human Locomotion

Background:

• The vestibular system is crucial for maintaining balance and stable locomotion.
• Deterioration of the vestibular system leads to gait instability, often measured by spatial-temporal parameters.
• Current gait measurements may not fully capture the complexities of motor control adjustments.

Purpose of the Study:

• To investigate the effects of different types of mastoid vibrations on gait control using the margin of stability (MOS).
• To test the hypothesis that MOS can reveal additional aspects of motor control altered by vestibular stimulation.
• To determine if mastoid vibrations induce asymmetric MOS patterns.

Main Methods:

• Twenty healthy adults participated in the study.
• Electromechanical vibrotactile transducers applied bilateral, unilateral, or no vibration to the mastoid processes.
• A motion capture system recorded margin of stability in the anterior-posterior (MOSap) and medial-lateral (MOSml) directions, along with their variabilities.

Main Results:

• Both bilateral and unilateral mastoid vibrations significantly increased MOSap, MOSml, and their variabilities compared to no vibration.
• Unilateral vibrations resulted in significantly larger MOSml, MOSml variability, MOSap, and MOSap variability than bilateral vibrations.
• A significant difference in MOSml was observed between dominant and non-dominant legs, with unilateral vibrations inducing greater MOSml symmetry.

Conclusions:

• Different mastoid vibration types differentially affect the margin of stability, indicating distinct motor control strategies under sensory conflict.
• Vestibular stimulation via mastoid vibrations alters dynamic gait stability, necessitating greater postural control.
• Medial-lateral balance control appears more actively engaged than anterior-posterior control during unilateral vestibular perturbation.