Pathology / Vestibular / Nystagmus / Alcohol
Alcohol
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clinical name = positional alcohol nystagmus (PAN) -
alcohol changes the relative density of the cupulae and the endolymph
- WHILE BLOOD ALCOHOL LEVELS ARE RISING, alcohol preferentially enters the cupulae (due to the nature of the blood supply), making them LESS DENSE than the endolymph è cupulae tend to float away from stereocilia è perception of movement
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opposite is true when blood concentrations are falling
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for example,lying with the RIGHT EAR DOWN è stereocilia deflection to the left in the right horizontal canal and to the right in the left horizontal canal (same direction as a head movement to the right) è slow eye movement to the left, followed by rapid eye movement to the right è RIGHTBEATING NYSTAGMUS
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when cupulae and endolymph densities equilibrate è PERIOD OF NO NYSTAGMUS
- AS BLOOD ALCOHOL LEVELS FALL, alcohol leaves the cupulae first, making them more dense than endolymph è POSITIONALLY DEPENDENT NYSTAGMUS IN THE OPPOSITE DIRECTION to what was originally observed