Nystagmus and postural instability after headshake in patients with vestibular dysfunction

Area of Science:

• Neurology
• Ophthalmology
• Vestibular Science

Background:

• Post-headshake nystagmus is a transient eye movement disorder often observed in patients with vestibulopathy.
• It is typically associated with symptoms like dizziness and dysequilibrium.
• The phenomenon is thought to result from persistent asymmetry in vestibulo-ocular reflex pathways after head movement.

Purpose of the Study:

• To investigate the effect of head shaking on postural control and eye movements.
• To determine if vestibular imbalance underlying post-headshake nystagmus correlates with postural instability.
• To compare postural stability changes after head shaking in healthy individuals, patients with vestibulopathy, and those with post-headshake nystagmus.

Main Methods:

• Utilized a dynamic platform device to quantify postural instability.
• Recorded eye movements using electrooculography.
• Assessed 21 patients and 10 healthy controls before and after passive horizontal head shaking (2 Hz for 20 seconds).
• Measured postural stability with eyes closed and modulated floor, focusing on the equilibrium score.

Main Results:

• Normal controls and vestibulopathic subjects without post-headshake nystagmus showed minimal transient postural instability post-headshake.
• Subjects exhibiting post-headshake nystagmus demonstrated a significant and robust decline in postural stability.
• This decline was observed irrespective of underlying caloric asymmetry.

Conclusions:

• Post-headshake nystagmus is a strong indicator of significant postural instability.
• The vestibular imbalance causing post-headshake nystagmus directly impacts balance control.
• Findings suggest a link between vestibulo-ocular reflex dysfunction and impaired postural stability.