Wernicke Korsakoff syndrome - Disorders of consciousness and memory

Wernicke-Korsakoff syndrome

Definition

Wernicke’s encephalopathy is a triad of confusion, ophthalmoplegia and ataxia. Korsakoff syndrome is a loss of short-term memory and disinhibition, leading to confabulation. These result from thiamine (vitamin B1) deficiency.

Aetiology

Usually seen in alcoholics, but may also be seen in starvation, malnutrition, parenteral feeding without vitamin supplements and chronic vomiting, e.g. hyperemesis gravidarum. Thiamine is present in fortified wheat flour (the natural thiamine is removed by milling, so it is replaced by law in most countries), fortified breakfast cereals, milk, eggs, yeast extract and fruit.

Pathophysiology

Thiamine is an essential factor for the maintenance of the peripheral nervous system and the heart. It is involved in glycolytic pathways, mediating carbohydrate metabolism. Deficiency leads to ischaemic damage to the brainstem.

If patients are given a large dose of sugar, the increased thiamine requirement to process this may precipitate the syndrome, so thiamine should be given together with intravenous glucose in a hypoglycaemic alcoholic.

Clinical features

Wernicke’s presents with confusion, double vision and unsteadiness, with an acute or chronic onset of nystagmus. Other signs include ptosis, abnormal pupillary reactions and altered consciousness. It may present with headache, anorexia, and vomiting. Untreated Wernicke’s can lead to irreversible Korsakoff ’s syndrome and/or death with coma within 2 weeks.

Occasionally, patients present with Korsakoff ’s, with a relatively selective although profound deficit in ability to acquire new memories. This leads to confabulation. Other intellectual functions are relatively well-preserved. Patients may have a peripheral neuropathy due to other nutritional deficiencies.

Investigations

Diagnosis is usually clinical, and on response to thiamine. Erythocyte transketolase activity and blood pyruvate are increased, but treatment should not be delayed whilst waiting for results.

Management

Urgent thiamine i.v. or p.o. Treatment of Wernicke’s encephalopathy may unmask Korsakoff ’s syndrome.

Prognosis

Recovery is prompt in most cases, occurring within 24–48 hours. There is more residual impairment in chronic cases when the diagnosis is delayed.