In this episode, I’ll discuss Wernicke’s encephalopathy.
Wernicke-Korsakoff syndrome is actually a combination of 2 different syndromes, both the result of severe thiamine deficiency. Wernicke’s encephalopathy is an acute disorder that has significant mortality and neurologic morbidity associated with it. Korsakoff syndrome is the chronic neurological disorder that arises if a patient with Wernicke’s encephalopathy is not treated adequately.
Risk factors
According to a review, over 75% of patients with Wernicke’s encephalopathy also abuse alcohol. Disorders associated with prolonged malnutrition account for the majority of non-alcoholic patients with Wernicke’s encephalopathy.
Recognition
There is no objective test for Wernicke’s encephalopathy; it is a clinical diagnosis.
The predominant clinical symptoms of Wernicke’s encephalopathy are encephalopathy (as shown by disorientation and decreased level of consciousness) and gait ataxia. Nystagmus is also traditionally considered a common finding but in a review, it occurred in a minority of the cases.
The Caine criteria can be used to assist in the diagnosis of Wernicke’s encephalopathy. Patients with at least 2 of the following 4 criteria are considered to have Wernicke’s encephalopathy according to the Caine criteria:
- Dietary deficiency
- Oculomotor abnormalities
- Cerebellar dysfunction
- Either altered mental status or mild memory impairment
Treatment
Quickly giving large doses of IV thiamine is the recommended treatment for Wernicke’s encephalopathy.
A regimen recommended by the UK Royal College of Physicians is 500 mg of thiamine IVMB over 30 minutes, three times daily for two days, then 250 mg IVMB or IM once daily for five days.
Administration of glucose without thiamine can precipitate or worsen Wernicke’s encephalopathy. This is because thiamine use requirements depend on the metabolic rate and the greatest need for thiamine is during periods of high glucose intake. Therefore giving glucose before thiamine only exacerbates the thiamine deficiency.
Unfortunately, there are no high-quality studies that have evaluated and elucidated the appropriate dose of thiamine to treat Wernicke’s encephalopathy. Oral thiamine absorption is saturable and only a few milligrams can be absorbed at any one time – not enough to treat Wernicke’s encephalopathy. The large 500 mg thiamine dose recommended by the UK Royal College of Physicians is only because of a few case reports that suggest lower doses of thiamine may not be sufficient to prevent permanent neurological damage.
Because of the generally safe nature of IV thiamine, most recommendations are to have a very low threshold for giving large doses of IV thiamine to potential Wernicke’s encephalopathy patients. For example, any patient with potentially prolonged malnutrition (whether or not from alcohol use) with altered mental status, gait ataxia, or nystagmus or other eye movement disorder is typically considered a candidate for IV thiamine therapy.
Prophylaxis
Prevention of Wernicke’s encephalopathy revolves around two principles:
1. Don’t give glucose to patients at risk of Wernicke’s encephalopathy without also giving thiamine – either at the same time or before glucose AND
2. Give IV thiamine to any patient at risk for Wernicke’s encephalopathy even if they do not have any symptoms of Wernicke’s encephalopathy.
The preventative dose of IV thiamine has not been subjected to prospective study. Most recommendations are to give 100 to 250 mg IV thiamine daily as a preventative measure.
Issues with thiamine administration
Although IV thiamine is considered safe, even in large doses for treating or preventing Wernicke’s encephalopathy, there are a handful of case reports of allergy, anaphylaxis, and sudden death temporally associated with thiamine administration going as far back as 1946. For this reason, I think it is appropriate to only give thiamine to those truly at risk of Wernicke’s encephalopathy and to reserve the highest doses such as 500 mg IV q8 hrs for patients with signs of Wernicke’s encephalopathy.
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