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Wernicke Encephalopathy

By Amay

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Etiology

Thiamine plays a vital role in the metabolism of carbohydrates as cofactor for several essential enzymes in the Krebs cycle & the pentose phosphate pathway (include alpha-ketoglutarate dehydrogenase, pyruvate dehydrogenase, & transketolase).

At thiamine deficiency, thiamine-dependent cellular systems begin to fail, resulting eventually in cell death.

Thiamine-dependent enzymes essential role in cerebral energy utilization propagate brain tissue injury by inhibiting metabolisme in brain regions with hirger metabolic demands & high thiamine turnover.

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Causes

Chronic alcoholisme, because it affects thiamine uptake & utilization

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Prolonged starvation2

Hyperemesis gravidarum3

Bariatric surgery4

Thiamine deficiency cause of :

Hemodialysis-induce thiamine deficiency in px with end stage renal disease.

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Causes

The most common inciting factor precipitating Wernicke encephalopathy in the setting of thiamine deficiency is infection (pneumonia, meningitis)

Iatrogenic exacerbation of Wernicke encephalopathy can occur with prolonged glucose or carbohydrate loading in the setting of thiamine deficiency.

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Epidemiology

The incidence can be as high as 12,5% in a population of alcoholics.

The prevalence approximately 2%. The male-to-female ratio is 1.7 : 1 Average age at onset is 50 years. Wernicke encephalopathy typically occurs

in adults with risk factors (alcoholism, post bariatric surgery, malnutrition), but can occur even in formula-fed infants if their formula lacks thiamine supplementation.

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Prognosis

Wernicke encephalopathy is a significantly disabling & potentially lethal condition that can be prevented or reserved if treated early.

Administration of thiamine improves the patient’s condition

Among patients surviving, develop Korsakoff psychosis, only about 20% eventually recover completely during long-term follow-up care.

Typical residual finding : nystagmus, gait ataxia, Korsakoff syndrome

A worse outcome may be expected in late-stage Wernicke encephalopathy, which is associated with elevated spinal fluid protein levels & diffuse slowing of postsinaptic potentials on EEG.

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Anamnesis

The classic triad: encephalopathy, ataxic gait, & some variant of oculomotor dysfunction.

There was any evidence of long-term alcohol abuse or malnutrition and any of the following acute confusion, ataxia, opthalmoplegia, memory disturbance, hypothermia with hypotension, & delirium tremens.

Korsakoff syndrome : potentially irreversible retrograde amnesia (inability to recall information) and anterograde amnesia (inability to assimilate new information), with varying degrees of other cognitive deficits.

Others risk factors: alcohol abuse, AIDS, malignancy, hyperemesis gravidarum, prolonged total parenteral nutrition, iatrogenic glucose loading in any predisposed patient, & other disorders associated with grossly impaired nutritional status

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Physical Examination

Ocular abN : nystagmus, bilateral lateral rectus palsies, conjugate gaze palsies, sluggishly reactive pupils, ptosis, scotomata, anisocoria.

Encephalopathy : global confusional state, disinterest, inattentiveness, agitation, mental status changes, stupor or coma (rare).

Gait ataxia : combination of polyneuropathy, cerebellar damage, & vestibular paresis.

Thiamine deficiency often affects the temperature-regulating center in the brainstem the classic triad : hypotermia, hypotension, & coma.

Hypotension because of thiamine deficiency-induced autonomic dysfunctions or cardiovascular systems (wet beriberi).

Manifestation in infants : constipation, agitation, apathy, vomiting, lack of appetite, and later, diarrhea, grunting, nystagmus, convulsions, unconciousness, & cardiomyopathy.

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Differential diagnostic

Psycosis NPH Cerebrovascular

accident Chronic hypoxia Closed-head injury Hepatic

encephalopathy Postictal state

Alcohol & substance abuse evaluation

Alcoholic ketoasidosis

Delirium tremens Delirium,

dementia, & amnesia

Stroke ischemic Withdrawal

syndromes

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Work Up

No spesific lab testComplete blood levels rules out

severe anemias or leukemiasSerum glucose levels exclude

hypoglycemia or hyperglycemiaPulseoxymetry &/ ABG exclude

hypoxia/hypercarbiaToxic drug screeningLP exclude CNS infections

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Work Up

Erythrocyte transketolase levels (0-15% is normally, 15-25% indicated thiamine deficiency, >25% severe deficiency).

Blood pyruvate & lactate measurements. Not spesific, but sensitive.

EEG.

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Work Up

Biomarker: assay for thiamineSerum electrolyte levels: hyperNa,

hyperCa must be excluded.Metabolic acidosis is secondary to

thiamine’s role in aerobic metabolism & the Krebs Cycle.

CT scan, MRI

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Treatment

Administration of thiamine can improves the patient’s condition to some degree in almost all cases; hwever, persistent neurologic dysfunction is common.

Doses 2 mg, 2-3 times daily parenterally. For alcoholic, given 500mg, 2-3 times daily. For infant, 50mg/day, for 2 weeks.

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L O G O

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