General description

Wernicke encephalopathy is a neurological disorder caused by a deficiency of vitamin B1 (thiamine), often associated with chronic alcoholism, malnutrition, severe infections, pregnancy hyperemesis, malignancies, and other conditions that lead to poor thiamine intake or absorption. It is characterized by a classic triad of symptoms: altered mental status, ocular motor dysfunction, and gait ataxia. In severe cases, untreated WE can progress to Korsakoff syndrome, marked by memory impairment, retrograde amnesia, and confabulation, often regarded as part of a spectrum called Wernicke-Korsakoff syndrome.

Thiamine plays a vital role as a coenzyme in carbohydrate metabolism and supports cell membrane integrity. Its deficiency impairs glucose oxidation, leading to cellular edema, particularly in regions with high metabolic activity such as around the third and fourth ventricles and the aqueduct. Chronic alcohol use is a significant risk factor as it impedes thiamine absorption in the gut and decreases thiamine storage in the liver, while poor nutrition associated with alcoholism further limits intake.

Other risk factors include conditions causing long-term malnutrition or vitamin deficiencies, such as dialysis, prolonged vomiting, starvation, gastric surgery, cancer, and AIDS. A sudden increase in carbohydrate intake, such as refeeding after starvation or glucose administration in at-risk patients, can precipitate WE by depleting thiamine levels.

In WE, symptoms can appear abruptly and include ocular abnormalities, such as horizontal or vertical nystagmus, partial ophthalmoplegia (e.g., lateral rectus palsy), and sluggish or unequal pupillary responses. Vestibular dysfunction without hearing loss is common, affecting gait stability, leading to a slow, wide-based gait. Patients may present with confusion, disorientation, apathy, inattentiveness, drowsiness, or stupor, and in advanced cases, coma or death can occur if untreated. Peripheral neuropathy is often present, along with autonomic dysfunction, which can manifest as tremor, agitation, hypothermia, orthostatic hypotension, or syncope. Genetic factors, such as abnormalities in the thiamine-processing enzyme transketolase, may also contribute to susceptibility.

Early treatment with thiamine can improve prognosis, but delays can lead to persistent memory deficits or Korsakoff syndrome.

Radiographic features

In Wernicke encephalopathy, MRI findings on diffusion-weighted imaging (DWI), T2-weighted imaging, and FLAIR sequences often show symmetrical high-signal intensities and contrast enhancement in specific brain regions. These regions include the medial thalami, periventricular areas around the third ventricle, periaqueductal gray matter in the midbrain, mammillary bodies, the tectum of the midbrain, and the anterior gray matter surrounding the fourth ventricle. Additional high-signal areas may be observed in the frontal cortex, dentate nuclei of the cerebellum, red nuclei, cranial nerve nuclei extending from the pons to the medulla (such as the abducens, facial, medial vestibular, and hypoglossal nuclei), and the basal ganglia. Basal ganglia involvement is more commonly seen in pediatric cases.

Hemorrhage can also occur in Wernicke-Korsakoff syndrome, especially in severe cases, and is associated with a poor prognosis.