What is the pathological cause of Wernike encephalopathy? What are the clinical manifestations?

Wernicke encephalopathy is a group of syndromes first described by Wernicke in 1881. It is rare in clinical practice, but because of its severe symptoms and life-threatening nature, some patients have considerable sequelae, so it is extremely harmful and must be taken seriously. So what are the causes and pathogenesis of this disease?

Causes

Wernicke encephalopathy is a serious neurological complication caused by vitamin B1 deficiency.

Patients with hyperemesis gravidarum suffer from severe vitamin B1 deficiency due to frequent vomiting and inability to eat, which leads to a decrease in pyruvate dehydrogenase activity; pyruvate cannot fully enter the trihydroxy acid cycle for complete oxidation.

When the activity of pyruvate dehydrogenase drops below 50% of the normal activity, sugar metabolism cannot proceed smoothly and tissue energy supply is affected.

The brain tissue has a large demand for sugar energy. Once the energy supply is insufficient, it can cause damage to brain cells.

In addition, vitamin B1 is also the main component of the nerve membrane of the nervous system. When it is severely deficient, it can affect the permeability of nerve cells, thereby causing their dysfunction, aggravating the corresponding brain tissue cell damage, and causing neurological and psychiatric symptoms.

Pathological mechanism

The pathogenesis of this disease is still unclear. The disease often affects the third and fourth ventricles and the area around the cerebral aqueduct. The mammillary bodies are the most vulnerable areas.

Its main pathological features are degeneration and necrosis of nerve cells, proliferation of capillaries and astrocytes, and punctate and sheet-like hemorrhage foci.

In the acute phase of Wernicke encephalopathy, fluid accumulates inside and outside cells, and small arteries, veins, and capillaries dilate with endothelial cell swelling and adventitia thickening, but neurons are relatively mildly affected or not affected.

In the subacute phase, patients may experience demyelination and vascular changes, and in some cases, hemorrhagic lesions.

In the chronic stage, neuronal loss may occur in the brain parenchyma, especially in the thalamus, leading to brain atrophy.

Clinical manifestations

The main symptoms of patients are memory loss, disorientation, ataxia and nystagmus. Some may also have amnesia and fictitious syndrome and paralysis of the extraocular muscles, pupil constriction, peripheral neuritis and hyporeflexia of the tendon.

The protein content of cerebrospinal fluid is occasionally increased.

Wernicke encephalopathy is often accompanied by signs of Korsakoff psychosis, which is characterized by marked memory loss, inability to acquire new information, and hyperarousal. These are often irreversible.

About 7%-10% of patients with severe hyperemesis gravidarum suffer from this disease. Once patients with hyperemesis gravidarum develop central nervous system symptoms, this disease should be considered.