Wernickes Encephalopathy

Wernicke's encephalopathy is a major complication of thiamine deficiency. The clinical presentation is highly characteristic and poses a medical emergency, because table 10.1.

Nervous System Manifestations in Major Vitamin Deficiencies

Vitamins

Neurologic Features

Bj thiamine

Wernicke-Korsakoff

*

encephalopathy

Cerebellar atrophy

Polyneuropathy

B6 pyridoxine

Seizures in infancy

Polyneuropathy

Bj2 cobalamine

Combined degeneration of

spinal cord

Polyneuropathy

Vitamin E, a-tocopherol

Spinocerebellar disorder

Degeneration of posterior

and lateral columns of

spinal cord

Axonal spheroids in cuneate

and gracile nuclei of

medulla

Folic acid

Polyneuropathy

Myelopathy

Nicotinic acid; niacin

Polyneuropathy

Myelopathy

Encephalopathy

Chromatolysis of neurons in

cerebral cortex, brainstem,

spinal cord

Dementia

untreated cases have a poor, even fatal, outcome. The onset is acute or subacute. The following cardinal features occur in various combinations:

• Ocular—Retinal hemorrhage, pupillary changes, extraocular muscle palsy, gaze palsy and nystagmus

• Autonomic—Hypo- or hypertension, hypo- or hyper-thermia, cardiac arrhythmias, respiratory failure

• Depression of alertness ranging from obtundation to coma

• Ataxia that is due to vestibular and/or cerebellar dysfunction

Blood transketolase activity is reduced and pyruvate level is elevated. MRI demonstrates the periventricular and thalamic lesions.

Pathology: The distribution of the pathologic process is distinctive and correlates well with the clinical presentation. The lesions are situated, usually symmetri-

Korsakoff Encephalopathy Pics

figure 10.1

Wernicke-Korsakoff encephalopathy. Schematic drawing of distribution of lesions.

figure 10.1

Wernicke-Korsakoff encephalopathy. Schematic drawing of distribution of lesions.

cally, in the walls of the third ventricle, extending into the mammillary bodies and dorsomedial nuclei of the thalami, and continuing caudally to the periaqueductal gray matter and floor of the fourth ventricle (Fig. 10.1, Table 10.2).

Grossly, the affected regions are soft, yellow to brown, finely granular, and contain petechial hemorrhages (Figs. 10.2 and 10.3). The histology is characterized by relative sparing of the neurons, destruction of myelin and, to a lesser degree, the axons; presence of lipid laden macrophages and astrocytic proliferation; prominent capillary endothelial hyperplasia; hemosid-erin pigments; and fresh pericapillary hemorrhages (see Figs. 10.2 and 10.3). In chronic cases, the mammillary bodies are atrophic, spongy, and devoid of myelin and axons (Fig. 10.4).

Wernicke's encephalopathy is often associated with the Korsakoff amnestic syndrome, which is characterized by impairment of recent memory; that is, an inability to form lasting imprints of new information while at the same time the remote memory is retained. The memory impairment includes both verbal and nonverbal material. Learning is greatly impaired or impossible. The sense of time and sequences of events are disturbed. Confabulation is common. Other cognitive functions are variably impaired but less severely than the memory function. Such personality changes as apathy and loss of initiative and insight are frequent.

The Korsakoff amnestic syndrome usually becomes evident after recovery from Wernicke encephalopathy; less frequently, it occurs independently. It is attributed to lesions in the dorsomedial nuclei of the thalamus and/or the mammillary bodies, both important relay stations in the limbic lobe, which provides the anatomic substrate for memory and learning.

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