Principles And Pitfalls in Alcohol Toxicity, Part 8


The affects of alcohol on the vestibular system are demonstrated in measurements which evaluate the ocular motor control. One of these is the eye movements called nystagmus (jerkiness). One of the tests is measuring the eye movements when the head is placed in a sideways position, and it is called Positional Alcohol Nystagmus (PAN). Positional Alcohol Nystagmus I (PAN I) is measurements of eye movements to the right side when the right side of the head is down, then to the left when the left side of the head is down. This occurs during peak BACs beginning at around 40 mg/100 ml (1). Positional Alcohol Nystagmus II (PAN II) typically is observed between 5-10 hours after drinking, and it is characterized by nystagmus in the opposite direction, compared to Positional Alcohol Nystagmus I (2). Both types of PAN are produced by the toxic effects of alcohol on the vestibular system. The literature has shown that the faster the rate of drinking, the faster PAN I appears (3). Another type of nystagmus is Horizontal Gaze Nystagmus (HGN). This is a nystagmus which is jerkiness in eye movements as the gaze is directed to the side when the head is in the upright position. Typically HGN is observed when the blood alcohol contents reach 80 mg/100 ml (4). The Horizontal Gaze Nystagmus appears to be pharmacologically specific to alcohol and therefore should be used to differentiate from the toxic effects of other mind altering drugs and chemicals. (5) Several studies have shown that alcohol leads to an increase in the sway, appearing in drinkers at BACs of 30-50 mg/100 ml (6,7,8,9) Postural control is sensitive, but other factors not related to alcohol must be taken into account such as physical difficulties with walking, pain in the joints or the ankles, physical deformation of the feet and effects of prescription medications.


  1. Money, K.E.; Johnson, W.H.; Corlett, B.M. “Role of semicircular canals in positional alcohol nystagmus” American Journal of Physiology. 208, 1065.
  2. Nito, Y.; Johnson, W.H.; Money, K.E. “The non-auditory labyrinth and positional alcohol nystagmus”. Acta Otolaryngology. 58, 65. 1964. 1964.
  3. Aschan, G.; Gergstedt, M. “Positional alcoholic nystagmus (PAN) in man following repeated alcohol doses.” Acta Otolaryngology, Suppl. 330, 15. 1975.
  4. Aschan, G. “Different types of alcohol nystagmus”. Acta Otolaryngology, Suppl. 140,69. 1958.
  5. Baloh, R.W.; Sharma, S.; Moskowitz, H; Griffith, R “Effect of alcohol and marijuana on eye movements”. Aviation, Space, and Environmental Medicine. P. 18. January, 1979.
  6. Fagan, D; Tiplady, B.; Scott, D.B. “Effects of ethanol on psychomotor performance”. British Journal of Anaesthesia. 59, 961. 1987.
  7. Wilson, J.; Erwin, G.; McClearn, G. “Effects of ethanol, ((. Behavioral sensitivity and acute behavioral tolerance”. Alcoholism: Clinical and Experimental Research. 8, 366. 1984.
  8. Niaura, R.S.; Wilson, G.T.; Westrick, E. “Self-awareness, alcohol consumption, and reduced cardiovascular reactivity”. Psychosomatic Medicine. 50, 360. 1988
  9. Lipscomb, T.R.; Nathan, P.E. Wilson, G.T.; Abrams, D.B. “Effects of tolerance on the anxiety-reducing functions of alcohol”. Archives of General Psychiatry. 37, 577. 1980.

About Nachman Brautbar, M.D., F.A.C.P.

Experienced in internal medicine, toxicology, occupational medicine, alcohol, drugs, and nephrology, with a specialization in toxicology; evaluation, analysis & interpretation of urine drug/alcohol tests; drug/alcohol concentrations in the blood; findings in blood and urine samples; assessment of driving under the influence. His list of academic appointments includes Associate Professor of Pharmacology and Medicine, and Clinical Professor of Medicine at the University of Southern California, School of Medicine. Dr. Brautbar is a peer reviewer for the Department of Human Health Services, earlier Agency for Toxic Substances and Disease Registry (ATSDR). Dr. Brautbar has been on the faculty of the National Judicial College and has lectured to judges on the issue of scientific evidence. He has been a visiting professor at national and international scientific institutions and centers such as Yale, Harvard, Mayo Clinic, and NIH. Dr. Brautbar is a fellow of the Collegium Ramazzini. Dr. Brautbar has testified in the California State Senate and the United States Senate on toxic groundwater contamination.

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