Don't seek, don't find: The diagnostic challenge of Wernicke's encephalopathy

Abstract

Wernicke's encephalopathy is caused by thiamine deficiency and has a range of presenting features, including gait disturbance, altered cognitive state, nystagmus and other eye movement disorders. In the past, Wernicke's encephalopathy was described almost exclusively in the alcohol-dependent population. However, in current times, Wernicke's encephalopathy is also well recognized in many other patient groups, including patients following bariatric surgery, gastrointestinal surgery, cancer and pancreatitis. Early recognition of Wernicke's encephalopathy is vital, as prompt treatment can restore cognitive or ocular function and can prevent permanent disability. Unfortunately, Wernicke's encephalopathy is often undiagnosed - presumably because it is relatively uncommon and has a variable clinical presentation. Clinical biochemists have a unique role in advising clinicians about potential nutritional or metabolic causes of unexplained neurological symptoms and to prompt consideration of thiamine deficiency as a potential cause in high-risk patient groups. The aim of this review is to summarize the clinical features, diagnosis and treatment of Wernicke's encephalopathy and to highlight some non-traditional causes, such as after bariatric surgery.

Keywords: Wernicke’s encephalopathy; bariatric surgery; deficiency; nutrition; nystagmus; obesity; ophthalmoplegia.

Figure 1.

Epidemiology of WE. (a) Incidence of WE is estimated to be less than 1% in the general population and 12.5% in alcohol-dependent patients. (b) The ratio of males and females with WE differs depending on cause of the disease. For non-alcohol-related causes, females outnumber males 1.69:1, while males with alcohol-related WE outnumber females 1.84:1. (c) Australia, Austria, Brazil, France, Germany, Norway and the United States have documented the prevalence of WE based on autopsies with average ranges from 0.6 to 2.2%.

Figure 2.

The bioactive form of thiamine is necessary for several cellular processes. TPP is the bioactive form of thiamine. It is a necessary cofactor in the pentose phosphate pathway, glycolysis and the TCA cycle. Additionally, it plays a role in maintaining equilibrium between pyruvate and lactate. TCA: tricarboxylic acid; TPP: thiamine pyrophosphate.

Figure 3.

Modification and transport of thiamine from food. Thiamine derived from food sources is hydrolysed into free thiamine in the lumen of the intestine. Free thiamine is passed through the intestinal wall to erythrocytes where it is converted to the bioactive form of thiamine – TPP. Blood carries TPP to organs such as the liver, heart, etc. To pass into the brain, TPP must cross the blood–brain barrier into the cerebrospinal fluid of the central nervous system before it diffuses throughout the brain. CSF: cerebrospinal fluid.