Subjective visual tilt and lateral instability after vestibular deafferentation

Area of Science:

• Neuroscience
• Vestibular System Research
• Human Physiology

Background:

• Patients with unilateral vestibular deafferentation (uVD) often experience chronic unsteadiness.
• The underlying reasons for varying degrees of unsteadiness in uVD patients remain unclear.
• Utricular compensation is a potential factor influencing balance after vestibular loss.

Purpose of the Study:

• To investigate if impaired utricular compensation, indicated by the subjective visual horizontal and vertical (SVH-V) test, impacts lateral postural control in uVD patients.
• To test the hypothesis linking SVH-V abnormalities to postural instability.

Main Methods:

• The study involved 28 patients who underwent translabyrinthine surgery for unilateral vestibular schwannoma.
• The subjective visual horizontal and vertical (SVH-V) test was administered six months post-surgery.
• Posturography data was collected and correlated with SVH-V test results.

Main Results:

• No significant increase in lateral or anterior-posterior postural sway was observed with increasing SVH-V tilt.
• Quotients for sway and Romberg quotients did not correlate with the degree of SVH-V tilt.
• These findings suggest that utricular function, as measured by SVH-V, is not directly associated with increased lateral sway in uVD.

Conclusions:

• Defective utricular function, indicated by deviations in perceived visual orientation, does not solely account for increased lateral postural sway in patients with unilateral vestibular deafferentation.
• Postural control in the lateral direction after uVD may depend on factors other than the degree of utricular compensation assessed by the SVH-V test.