Positional Alcohol Nystagmus occurs due to what factor in the vestibular system?

Positional Alcohol Nystagmus (PAN) is specifically associated with the effects of alcohol on the vestibular system, particularly the impact of alcohol on the endolymph fluid in the inner ear. The correct answer highlights that PAN occurs due to unequal concentrations of alcohol in the blood, which influences the density of the endolymph. Alcohol can create a differential concentration in the blood and associated structures, leading to altered vestibular responses and causing the eyes to demonstrate nystagmus when the head is in specific positions.

This phenomenon is further intensified when the body is in a vertical position, as the alcohol impacts the fluid dynamics within the inner ear. As a result, individuals may experience spontaneous eye movements that are not aligned with typical functioning due to these concentration variations. Understanding this helps clarify why certain individuals exhibit nystagmus in response to specific head positions when consuming alcohol.