Wernicke Encephalopathy

What happens in Wernicke encephalopathy

Thiamine is needed by brain cells to turn glucose into energy. The body stores only a few weeks' supply, so a period of poor intake, poor absorption or increased need can run stores down. Without thiamine, brain cells in regions with high energy demand, such as the mammillary bodies, the thalamus and areas around the brainstem, swell and are damaged.

Giving glucose (sugar) to a thiamine-deficient person can use up the last thiamine and trigger or worsen Wernicke encephalopathy. That is why hospitals give thiamine before or with glucose in people at risk, although low blood sugar must still be treated immediately.

Causes and risk factors

• Alcohol use disorder: the most common cause in high-income countries. Alcohol reduces thiamine absorption and storage, and diets are often poor.
• Prolonged vomiting: hyperemesis gravidarum, bowel obstruction, chemotherapy
• Weight-loss (bariatric) surgery, especially with vomiting in the first months
• Eating disorders and starvation, and malnutrition from poverty or neglect
• Cancer, AIDS, kidney dialysis and long-term intravenous feeding without vitamins
• Refeeding after a long period of poor intake (refeeding syndrome)

Wernicke encephalopathy symptoms

The classic triad

Only about 1 in 10 to 1 in 5 people show all three, so doctors use broader criteria. Many cases are missed, especially in people who are intoxicated or in withdrawal.

Other signs

• Low body temperature and low blood pressure
• Memory loss
• Signs of other nutritional deficiencies or of heart failure (wet beriberi), in severe deficiency
• In advanced cases, stupor, coma and death

Diagnostic criteria

Doctors often use the Caine criteria in people with alcohol use disorder. Wernicke encephalopathy is likely if two or more of these are present:

1. Dietary deficiency
2. Eye movement abnormalities
3. Cerebellar problems, such as unsteadiness
4. Altered mental state or mild memory impairment

Diagnosis

Wernicke encephalopathy is a clinical diagnosis. Because harm can happen within hours and treatment is safe, thiamine is given as soon as it is suspected.

• Blood tests: thiamine levels can be sent before treatment, but results take days and a normal level does not exclude it. Magnesium, glucose, electrolytes, liver function and alcohol level are checked.
• MRI brain: may show symmetrical changes around the third ventricle, the mammillary bodies and the thalamus. A normal MRI does not rule it out.
• Other causes of confusion are considered, such as alcohol withdrawal, low blood sugar, head injury, liver encephalopathy, infection and stroke.

Treatment

• High-dose intravenous thiamine, given several times a day for several days, then thiamine by mouth for months. Thiamine by mouth alone is too poorly absorbed for acute treatment.
• Magnesium replacement, because thiamine cannot work properly when magnesium is low.
• Nutrition and fluids, with glucose given alongside thiamine, not before it.
• Management of alcohol withdrawal where relevant.
• Rehabilitation with physical and occupational therapy for balance and walking.

Thiamine is very safe. Serious allergic reactions to IV thiamine are rare, and the benefit far outweighs the risk.

Recovery and Korsakoff syndrome

• Eye signs often improve within hours to days of treatment.
• Unsteadiness and confusion usually improve over days to weeks, but walking problems can persist.
• Memory: many people, especially those whose treatment was delayed, develop Korsakoff syndrome, a lasting problem with forming new memories, sometimes with confabulation (filling memory gaps with invented stories). The combination is called Wernicke-Korsakoff syndrome.

Some people improve gradually over a year with abstinence from alcohol and good nutrition. Others need long-term support. Untreated Wernicke encephalopathy carries a significant risk of death.

Prevention

• Thiamine supplements for people who drink heavily, are malnourished or have had weight-loss surgery
• Thiamine before glucose-containing fluids for at-risk patients in hospital
• Early treatment of prolonged vomiting, including in pregnancy
• Support to reduce or stop drinking

Frequently asked questions

What are the three symptoms of Wernicke encephalopathy?

The classic triad is confusion, abnormal eye movements (such as nystagmus or eye muscle weakness causing double vision) and ataxia, an unsteady, wide-based walk. Most patients have only one or two of these, so any of them in someone at risk of thiamine deficiency should prompt urgent treatment.

Can Wernicke encephalopathy be reversed?

Often, if treated quickly. Eye signs usually improve within days and confusion and walking within weeks after high-dose thiamine. Delayed treatment raises the chance of permanent damage, including Korsakoff syndrome, which causes lasting memory problems and may improve only partly.

What is the difference between Wernicke encephalopathy and Korsakoff syndrome?

Wernicke encephalopathy is the acute, emergency phase of thiamine deficiency, with confusion, eye problems and unsteadiness. Korsakoff syndrome is the chronic result, with severe difficulty forming new memories and sometimes confabulation. Together they are called Wernicke-Korsakoff syndrome.

Can you get Wernicke encephalopathy without drinking alcohol?

Yes. It can follow any severe thiamine deficiency, such as prolonged vomiting in pregnancy, weight-loss surgery, eating disorders, cancer, long-term dialysis, or intravenous nutrition without vitamins. Non-alcohol cases may be missed because doctors do not always suspect it.

How quickly does Wernicke encephalopathy develop?

It can appear over days once thiamine stores are depleted, often triggered by an illness, a bout of vomiting, or receiving glucose without thiamine. Body stores last only a few weeks, so people with poor intake or high losses can become deficient surprisingly quickly.