Direction-changing nystagmus has been seen after the ingestion of ethanol in both animals and man. The direction of the nystagmus is dependent upon the position of the head and is thus called Positional Alcohol Nystagmus (PAN). This article provides information about positionally dependent, direction-changing nystagmus in human beings after the ingestion of glycerol (1.5 g/kg). Electronystagmographic recordings were made and serum glycerol levels were repeatedly determined over a period of 7 hours. The resulting data compliment earlier work done with ethanol. These data provide support for a buoyancy hypothesis to explain positional nystagmus after ingestion of water-soluble molecules with differing specific gravities.
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