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Think CANON for signs of alcohol-induced amnesia

Vol. 4, No. 3 / March 2005

Wernicke’s encephalopathy is often missed in clinical practice.1 Left untreated, the alcohol-induced amnestic disorder can progress to Korsakoff’s syndrome, a form of permanent short-term memory loss from which four out of five patients do not recover.2

Why Wernicke’s is missed

Lesions in the medial dorsal nucleus of the thalamus, hippocampus, and mammillary bodies cause signs and symptoms of Wernicke’s. Associated psychotic symptoms—including delusions, confusion, agitation, blunted to apathetic affect, and confabulation—may incorrectly suggest delirium tremens, alcohol-induced psychosis, delusional disorder, or dementia.

Key features of Wernicke’s are remembered with the acronym CANON:

Clouded consciousness with impaired orientation and inability to sustain attention to environmental stimuli.

Ataxia, primarily affecting gait

Nystagmus, mainly horizontal

Ophthalmoplegia accompanied by lateral orbital palsy and gaze palsy, which is usually bilateral. Anisocoria and a sluggish reaction to light also are present.

Neuropathy, mainly peripheral.

Early recognition and treatment is essential as early-stage Wernicke’s responds rapidly to parenteral thiamine, 100 mg/d for 5 to 7 days. Oral thiamine, 100 mg two to three times daily, is then given for 1 to 2 weeks.


1. Muralee S, Tampi RR. Sobering facts about a missed diagnosis. Current Psychiatry 2004;3(10):73-80.

2. Sadock BJ, Sadock VA. Kaplan and Sadock’s synopsis of psychiatry (9th ed). Philadelphia: Lippincott Williams and Wilkins; 2003:406.

Dr. Maju Mathews is attending psychiatrist, Drexel University College of Medicine, Philadelphia, PA.

Dr. Adetunji is attending psychiatrist, Kirby Forensic Psychiatric Center, New York, NY.

Dr. George is a first-year psychiatry resident, Albert Einstein Medical Center, Philadelphia.

Dr. Manu Mathews is a first-year psychiatry resident, Cleveland Clinic Foundation, Cleveland, OH.

Dr. Dandugula is a general practitioner, Dumfries, UK.

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