How to assess, treat Wernicke's encephalopathy
What does vitamin B1 deficiency mean in the prehospital environment?
Updated January 6, 2017
One of your favorite professional drinkers presents as usual: unstable on his feet, confused as to place and time and exhibits involuntary jerking movements of the eyes on lateral gaze (horizontal gaze nystagmus). Transport is uneventful. On return to the receiving facility several days later, you are informed that your patient was hospitalized and subsequently died. Autopsy revealed he suffered from Wernicke's encephalopathy.
If you're like me, you have to refresh your memory on this one as it is an uncommon condition, and when it does occur it is often unrecognized unless an autopsy is performed; maybe that's why it is thought to be uncommon. Wernicke's encephalopathy is caused by a deficiency of thiamine, Vitamin B1.
The discovery of vitamins evolved in the 1800s and early 1900s as researchers were solving the mysteries of vitamin deficiency diseases such as scurvy, a vitamin C deficiency, and rickets, a vitamin D deficiency. Their research ultimately determined the existence of essential nutritional components that produce disease if inadequate amounts are contained in the diet. Initially the missing culprit was thought to be a nitrogen-containing chemical compound called an amine as these compounds are involved in many cellular functions and structures such as amino acids, the building blocks for protein. These "vital amines" or vitamins turned out to be a variety of not necessarily amine based compounds, but were all vital to maintaining life; the term 'vitamin' stuck.
Dietary thiamin is obtained from food such as fortified breads, cereals, pasta, whole grains, wheat germ, lean meats, fish, dried beans, peas and soybeans, and it is stored in the liver. Medical conditions that can cause thiamine deficiency are those that produce one or more of the following: inadequate dietary intake, decreased absorption from the gastrointestinal tract, and/or reduced storage in the liver.
The patients with potential thiamine deficiency most familiar to us are the ones who suffer from chronic alcohol abuse. They are a triple risk because they frequently don't eat, absorb or store adequate nutrients. Examples of other patient conditions that can lead to thiamine deficiency include HIV/AIDS, cancer, hyperemesis gravidarum, gastric bypass and prolonged parenteral nutrition.
Thiamine is essential for the conversion of glucose into energy in the brain. When thiamine levels are low the cell's metabolic machinery may be unable to meet the energy requirements in the brain, especially in the most active areas of the brain and cell damage may occur. Additionally, low thiamine levels may cause the formation of toxic substances because of the inability of the brain cell to normally process glucose. Increasing the glucose supply to the thiamine deficient brain (as with intravenous D50) may increase the metabolic pollution and induce Wernicke's encephalopathy.
Wernicke's signs and symptoms
The classic Wernicke's patient presentation is a triad of:
- Ocular changes
- Altered mental status
- Difficulty walking or standing (gait ataxia)
Ocular finding are most often nystagmus, those jerking eye movements when the patient looks side to side or up and down. Less common external eye signs include pupil dilation or constriction, and lid droop. The altered mental status may vary from mild confusion to coma. And gait disturbances range from a mild staggering gait or broad based gait to complete inability to get up and go.
The problem with the Wernicke's classic triad is that it only occurs in one third of the cases. So you should be suspicious of any patient at risk for dietary insufficiency and the presence of any symptom included in the triad. Overall, the most common sign of Wernicke's is an altered mental status and the most common ocular sign is nystagmus, most often on horizontal gaze.
Prehospital treatment of Wernicke's
So what does this mean in the prehospital environment? It's all about prevention. Let's not be the ones who push the patient over the thiamine edge. Hypoglycemic patients should receive glucose, and in the patient at risk of thiamine deficiency, they should receive thiamine before or during glucose administration. Does this mean some of our patients will receive thiamine unnecessarily? Yes, but the risk of an adverse reaction is extremely low and the potential benefit if the patient is indeed thiamine deficient may be life preserving.
But what if you don't have thiamine and your patient is hypoglycemic? Titrate glucose to effect and improve the patient's symptoms but don't induce hyperglycemia.
Wernicke's encephalopathy is an acute condition that can be prevented or treated by timely thiamine administration. If thiamine is not provided, provided too late or provided in the wrong route or dose, the patient may die or develop a chronic debilitating condition called Korsakoff's psychosis or syndrome. Korsakoff's is characterized by permanent short term memory loss, apathy and confabulation (making up stories to fill gaps in the memory).
Even in this modern age in a country overwhelmed with vitamin makers, sellers and takers, we encounter patients in the field with the potential for debilitating or fatal vitamin deficiencies. So maintain vigilance, be suspicious and keep your thiamine handy.
1. Donnino MW, Vega J, Miller J, Walsh M. Myths and Misconceptions of Wernicke's Encephalopathy: What Every Emergency Physician Should Know. Ann Emerg Med.2007;50:715-721.
2. Charness ME, SO YT. (2010). Wernicke's encephalopathy. In M. Aminoff (Ed.), UpToDate. Available from www.uptodateonline.com.
3. Lanska, Douglas J. (2009). Chapter 30 Historical aspects of the major neurological vitamin deficiency disorders: the water-soluble B vitamins. Handbook of clinical neurology / edited by P.J. Vinken and G.W. Bruyn, 95. Retreived from www.biomedsearch.com/nih/Chapter-30-Historical-aspects-major/19892133.html.