Wernicke encephalopathy (WE) is a neurological disorder induced by thiamine, vitamin B1, deficiency. Wernicke's encephalopathy may result from inadequate intake or absorption of thiamine coupled with continued carbohydrate ingestion.
Characteristics of Wernicke's encephalopathy
The characteristic clinical triad is that of ophthalmoplegia, ataxia, and global confusion. However, only one-third of patients with acute Wernicke’s disease presents with the classic clinical triad.
Most patients are profoundly disoriented, indifferent, and inattentive, although rarely they have an agitated delirium related to ethanol withdrawal. If the disease is not treated, stupor, coma, and death may ensue.
Ocular motor abnormalities include horizontal nystagmus on lateral gaze, lateral rectus palsy (usually bilateral), conjugate gaze palsies, and rarely ptosis. Gait ataxia probably results from a combination of polyneuropathy, cerebellar involvement, and vestibular paresis.
The pupils are usually spared, but they may become miotic with advanced disease
The Wernicke-korsakoff syndrome is an important entity characterized by paralysis of the external eye muscles, ataxia, and a confused state that can progress to coma and death.
Most commonly results from chronic alcohol abuse and accompanied by organic amnesia and other nutritional polyneuropathies. It is apparently associated with thiamine deficiency but is rarely seen in the absence of alcoholism.
Wernicke's encephalopathy represents the acute phase of this disease which later blends in with the perceptual and behavioral problems associated with alcohol withdrawal.
A distinguishing feature of Wernicke's encephalopathy is the longer duration of the confusional state and the relative absence of the agitation that would be expected during withdrawal.
Thiamine (vitamin B6) is a cofactor of several enzymes, including transketolase, pyruvate dehydrogenase, and α-ketoglutarate dehydrogenase. Thiamine deficiency produces a diffuse decrease in cerebral glucose utilization and results in mitochondrial damage.
Glutamate accumulates due to impairment of α-ketoglutarate dehydrogenase activity and, in combination with the energy deficiency, may result in excitotoxic cell damage.
Symptoms and signs
The patients may develop acutely.
Patients may become ataxic, confused, drowsy, or stuporous.
Nystagmus and partial ophthalmoplegia are characteristic findings.
Peripheral nerve pain thresholds are often elevated, and many patients develop severe autonomic dysfunction characterized by sympathetic hyperactivity (e.g. tremor, agitation) or hypoactivity (e.g. hypothermia, postural hypotension, syncope).
- Wernicke’s encephalopathy is a medical emergency and requires immediate administration of thiamine, in a dose of 100 mg either IV or IM. The dose should be given daily until the patient resumes a normal diet and should be begun prior to treatment with IV glucose solutions. This is because glucose infusions may precipitate Wernicke’s encephalopathy in a previously unaffected patient or cause a rapid worsening of an early form of the disease.
- The next steps are rehydration to restore blood volume, correction of electrolyte abnormalities, and initiation of general nutritional therapy, including multivitamins.
- Advanced cases require hospitalization and close supervision.
- Because of the importance of thiamine in this pathologic condition, all patients suspected of having Wernicke-Korsakoff syndrome should receive thiamine therapy (50 mg intravenously once and 50 mg intramuscularly repeated daily until a normal diet is resumed).
- Often, the ocular signs, ataxia, and confusion improve upon prompt administration of thiamine.
- However, most patients are left with a chronic disabling memory disorder known as Korsakoff's psychosis.
Patients who recover show improvement in ocular palsies within hours after the administration of thiamine, but horizontal nystagmus may persist.
Ataxia improves more slowly than the ocular motor abnormalities. Approximately half recover incompletely and are left with a slow, shuffling, wide-based gait and an inability to tandem walk.
Apathy, drowsiness, and confusion improve more gradually.
As these symptoms recede, an anamnestic state with impairment in recent memory and learning may become more apparent (Korsakoff’s psychosis).
Korsakoff’s psychosis is frequently persistent; the residual mental state is characterized by gaps in memory, confabulation, and disordered temporal sequencing.