Wernicke encephalopathy and Korsakoff syndrome

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Thiamine is required for cerebral glucose metabolism. Body stores are limited, and prolonged undernutrition, vomiting or impaired absorption can create rapid deficiency. Alcohol contributes through reduced intake, impaired intestinal absorption, reduced hepatic storage and disturbed utilisation. High carbohydrate delivery increases thiamine demand, which is why emergency replacement accompanies feeding. Wernicke disease also occurs without alcohol, and anchoring on alcohol history misses people after hyperemesis, bariatric surgery or prolonged critical illness.

The clinical phenotype is broader than the textbook triad. Mental change includes inattention, disorientation, apathy, drowsiness, agitation or coma. Eye findings include nystagmus, bilateral abduction weakness, ophthalmoplegia and gaze palsy. Gait dysfunction ranges from mild broad-based instability to inability to stand and can coexist with peripheral neuropathy or vestibular impairment. Hypothermia, hypotension and autonomic dysfunction may occur in severe disease. A serum thiamine result or normal MRI cannot exclude the diagnosis.

Korsakoff syndrome represents chronic injury to memory networks, classically involving mammillary and thalamic circuits. Immediate registration or conversational fluency can mask profound inability to retain new information; confabulation is not deliberate lying. Assessment should occur after intoxication, withdrawal, delirium, infection and hepatic encephalopathy are stabilised. Recovery can continue for months with abstinence, nutrition, repetition and environmental structure, but many people need formal capacity, finance, medication and accommodation support.

Key points

Wernicke encephalopathy is an acute thiamine-deficiency brain disorder and a medical emergency; the complete triad of confusion, eye signs and ataxia is absent in many patients.
Suspect it in alcohol dependence, malnutrition, prolonged vomiting, hyperemesis, bariatric surgery, cancer, starvation, dialysis or another state of depleted intake or increased requirement.
Operational clinical recognition improves when at least two of dietary deficiency, ocular abnormality, cerebellar dysfunction and altered mental state or memory impairment are present.
Give high-dose parenteral thiamine immediately when Wernicke disease is suspected; oral absorption is unreliable in the acute high-risk state and laboratory confirmation must not delay therapy.
If hypoglycaemia is present, treat it immediately and administer thiamine before or alongside carbohydrate as soon as possible; do not withhold life-saving glucose while sourcing thiamine.
Check and replace magnesium because thiamine-dependent enzymes require it, and identify phosphate, potassium, infection, liver disease, head injury and withdrawal occurring at the same time.
Korsakoff syndrome is a persistent amnestic disorder with severe new-learning impairment, variable remote-memory loss, executive dysfunction, apathy and confabulation that often follows inadequately treated Wernicke episodes.
After acute treatment, continue nutrition, alcohol treatment, cognitive rehabilitation, safeguarding and supported-living assessment; thiamine prevents further injury but does not reliably reverse established Korsakoff disability.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Alcohol-related malnutrition

Alcohol dependence combines poor intake, impaired absorption, reduced storage and increased metabolic need, making thiamine deficiency common and often multifactorial.

Prolonged vomiting

Hyperemesis, gastrointestinal disease and recurrent vomiting can rapidly deplete limited thiamine stores, even without alcohol exposure.

Bariatric and malabsorptive disease

Gastric surgery, malabsorption and severe dietary restriction reduce thiamine uptake and can produce acute neurological decline.

Severe systemic catabolism

Cancer, starvation, dialysis and refeeding increase requirements or losses and may expose previously marginal thiamine reserve.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Thiamine cofactor depletion
Loss of thiamine pyrophosphate impairs several enzymes essential for cerebral glucose metabolism, mitochondrial function and cellular energy production.
2
Regional energy failure
Energy failure injures medial thalamic, mammillary, periaqueductal and cerebellar regions, producing the characteristic cognitive, ocular and gait syndromes.
3
Acute network dysfunction
Eye-movement, gait, arousal and memory circuits become dysfunctional, often without all three features of the classic clinical triad.
4
Permanent amnestic injury
Untreated or repeated episodes destroy mammillary and connected memory networks, producing persistent Korsakoff amnesia and confabulation.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Altered mental state

Inattention, disorientation, apathy, behavioural change, drowsiness or unexplained delirium in a depleted patient can be the dominant Wernicke feature.

Ocular motor syndrome

Horizontal gaze-evoked nystagmus, impaired abduction, conjugate gaze palsy or complex ophthalmoplegia may improve within hours or days of treatment.

Gait and stance dysfunction

Broad-based gait, truncal instability or inability to stand may reflect cerebellar vermis injury compounded by neuropathy and general weakness.

Non-alcohol risk setting

Persistent pregnancy vomiting, gastric surgery, prolonged parenteral nutrition without vitamins, malignancy or starvation can produce severe disease without alcohol exposure.

Korsakoff memory pattern

Disproportionate anterograde amnesia, impaired temporal sequencing and poor insight persist despite improving alertness, while social conversation can appear deceptively fluent.

Confabulation

The brain fills memory gaps with inaccurate but sincerely held accounts, which may vary with questioning and should not be interpreted as intentional deception.

Red flags requiring action

Coma, airway compromise, hypothermia, hypotension or severe hypoglycaemia requires simultaneous resuscitation and intravenous thiamine rather than transfer to a routine detoxification setting.
Focal deficit, head trauma, seizure or anticoagulant use requires urgent brain imaging because subdural haemorrhage or stroke can coexist with alcohol-related risk.
Fever, neck stiffness, hypoxia or haemodynamic instability requires infection and critical-illness evaluation alongside empirical Wernicke treatment.
Autonomic hyperactivity, hallucinations and seizure during alcohol cessation can indicate severe withdrawal or delirium tremens requiring a separate monitored benzodiazepine pathway.
Refusal of food, medication or accommodation in profound amnesia requires decision-specific capacity assessment and safeguarding rather than assuming an informed choice.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Clinical diagnostic assessmentFirst step
Why
Identify risk plus mental, ocular, cerebellar and nutritional features and initiate treatment immediately.
Interpretation and limitations
The full classic triad is insensitive; meeting two operational feature groups in a high-risk context strongly supports empirical parenteral therapy.
02
Glucose, electrolytes and magnesium
Why
Find hypoglycaemia and magnesium, phosphate, potassium or sodium disturbance that worsens encephalopathy and treatment response.
Interpretation and limitations
Correct life-threatening glucose immediately, replace cofactors through the local protocol and monitor for shifts during nutrition restoration.
03
Full blood count, liver, renal and infection profile
Why
Identify anaemia, sepsis, hepatic decompensation and organ dysfunction contributing to confusion or altering treatment safety.
Interpretation and limitations
Abnormal liver tests do not prove hepatic encephalopathy and normal indices do not exclude thiamine depletion; diagnose concurrent conditions on their own evidence.
04
MRI brain
Why
Support an uncertain diagnosis and investigate alternative structural disease when the patient is stable enough.
Interpretation and limitations
Symmetric medial thalamic, mammillary-body, periaqueductal or tectal abnormalities are supportive, but sensitivity is insufficient to withhold treatment after a normal scan.
05
CT brain
Why
Urgently exclude haemorrhage, trauma, hydrocephalus or a large stroke when focal signs, injury or reduced consciousness warrant it.
Interpretation and limitations
CT does not exclude Wernicke disease and imaging must occur alongside thiamine rather than before it.
06
Thiamine measurement
Why
Provide supportive biochemical evidence or investigate unusual recurrent deficiency when a suitable assay is available.
Interpretation and limitations
Draw before replacement only if immediately possible; circulating concentration and assay delay cannot determine emergency treatment.
07
Neuropsychological assessment
Why
Characterise memory, executive, attention and functional deficits after acute delirium and withdrawal have settled.
Interpretation and limitations
Use repeated supported assessment and collateral history because severe new-learning impairment undermines self-report and one early result may improve with abstinence.
08
Alcohol and nutrition assessment
Why
Define dependence, withdrawal risk, intake, weight loss, vitamin access, liver disease and the social drivers of recurrent depletion.
Interpretation and limitations
A low alcohol report does not exclude a non-alcohol cause; conduct the conversation non-judgementally and corroborate only with consent or safeguarding justification.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Alcohol intoxication or withdrawal

Ataxia, confusion and tremor can reflect alcohol state, but this cannot safely exclude simultaneous thiamine-deficiency brain injury.

Hepatic or metabolic encephalopathy

Asterixis, organ failure and biochemical disturbance support a systemic encephalopathy, although this may coexist with malnutrition and thiamine deficiency.

Encephalitis or stroke

Fever, focal deficit, seizure and structural or inflammatory findings require neurological emergency assessment beyond empirical thiamine.

Degenerative or pressure-related gait disorder

Slow gait-cognitive decline with ventriculomegaly or parkinsonism differs from an acute nutritional encephalopathy, though histories may be unreliable.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01SUSPECTPossible Wernicke encephalopathyFirst stepA nutritionally vulnerable patient has confusion, eye signs, gait dysfunction or memory change.

1Perform ABC assessment, check capillary glucose and temperature, identify ocular and gait findings and seek trauma, infection, withdrawal and liver clues.
2Administer high-dose intravenous thiamine immediately through the local Wernicke protocol and give glucose without delay if hypoglycaemic.
3Check magnesium, phosphate, potassium, renal and liver function and replace important abnormalities while planning controlled nutrition.
4Admit and reassess frequently; continue parenteral therapy for the guideline-defined course unless the diagnosis is excluded and investigate competing causes in parallel.

02PREVENTHigh risk without current encephalopathyAlcohol dependence, malnutrition, decompensated liver disease, prolonged vomiting or planned feeding creates major thiamine risk.

1Assess intake, weight loss, vomiting, neuropathy, cognition and eye and gait signs carefully so early Wernicke disease is not misclassified as prophylaxis.
2Provide oral or parenteral prophylactic thiamine according to the NICE and national alcohol guideline risk category and route reliability.
3Give vitamin support before and during withdrawal treatment or nutrition and manage magnesium and refeeding risk.
4Create a discharge supply, alcohol-treatment referral, dietary plan and follow-up responsibility rather than ending replacement at hospital discharge.

03WITHDRAWALWernicke risk with alcohol withdrawalA dependent drinker is reducing alcohol and has tremor, autonomic symptoms, hallucination or seizure risk.

1Treat suspected Wernicke disease independently with parenteral thiamine and do not assume confusion is explained solely by withdrawal.
2Use a monitored symptom-triggered or fixed-dose benzodiazepine regimen from the local withdrawal protocol according to severity, liver function and setting.
3EscalationMonitor observations, consciousness, fluid and electrolytes and escalate delirium tremens, seizure, arrhythmia or respiratory depression to higher-acuity care.
4Link acute detoxification to relapse-prevention treatment, psychosocial support, nutrition and housing or safeguarding needs.

04KORSAKOFFPersistent amnestic syndromeSevere new-learning difficulty persists after acute encephalopathy, intoxication and withdrawal improve.

1Continue thiamine and nutrition and exclude subdural disease, hepatic encephalopathy, dementia, depression and ongoing substance effects.
2Obtain collateral history and formal cognitive and functional assessment over time, including medication, finance, cooking and vulnerability risks.
3Provide abstinence support, errorless learning, repetition, written or electronic cues and a stable structured environment through neurorehabilitation.
4Complete decision-specific capacity, safeguarding, benefits, accommodation and carer planning and reassess recovery over months before assuming a fixed endpoint.

Key medicines and prescribing safety4 treatments · regimens, roles and cautions

Rapidly supplies the cofactor required for cerebral energy metabolism and limits preventable death, permanent amnesia and neurological disability.

Intravenous thiamine

For suspected Wernicke encephalopathy, use the current hospital high-dose regimen, commonly 300–500 mg intravenously three times daily for 3–5 days, then continue guided by clinical response and national guidance.

Give in a monitored setting with anaphylaxis treatment available, but recognise that serious reactions are rare and the risk of undertreatment is substantial.

Maintains thiamine availability during nutritional recovery and reduces recurrence after acute parenteral treatment.

Oral thiamine after stabilisation

Continue an oral dose and duration from the local alcohol or nutrition pathway after the parenteral course, often in divided daily dosing while malnutrition or alcohol risk persists.

Oral absorption is limited in alcohol dependence and is not adequate initial therapy for suspected Wernicke encephalopathy; ensure supply and adherence at discharge.

Restores an essential cofactor for thiamine-dependent enzymes and treats arrhythmia, weakness and seizure risk from hypomagnesaemia.

Magnesium replacement

Replace documented magnesium deficiency orally or intravenously according to severity, ECG, renal function and the current electrolyte protocol.

Intravenous replacement requires monitoring and dose reduction in renal impairment; also correct potassium and calcium abnormalities that may be difficult to resolve until magnesium improves.

Prevents or treats alcohol-withdrawal seizure and delirium but does not treat the thiamine-deficiency brain lesion itself.

Benzodiazepine for concurrent withdrawal

Use chlordiazepoxide or a liver-appropriate alternative at the symptom-triggered or fixed dose specified by the supervised alcohol-withdrawal protocol, with frequent sedation review.

Adjust for liver disease, age and respiratory risk, avoid stacking with alcohol or opioids and do not let sedation obscure worsening encephalopathy or head injury.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Korsakoff syndrome

Severe new-learning failure, remote-memory loss, apathy and confabulation can persist permanently after the acute neurological signs improve.

Aspiration, falls and injury

Ataxia, abnormal eye movements and confusion can cause falls, fractures, head injury, unsafe swallowing and aspiration pneumonia.

Refeeding and cardiac complications

Associated phosphate, magnesium, potassium and fluid shifts can cause arrhythmia, heart failure, respiratory weakness and seizures.

Coma and death

Continuing energy failure and coexisting infection, hypoglycaemia or withdrawal can progress to profound unconsciousness and fatal multi-organ illness.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Repeat mental state, eye movements, gait or truncal stability and peripheral neurology daily during acute treatment and document the direction of change.
Monitor glucose, magnesium, phosphate, potassium, renal function, fluid balance and ECG when depletion or refeeding risk is substantial.
Observe during intravenous administration according to local policy and distinguish rare hypersensitivity from undertreated sepsis or withdrawal deterioration.
Track food intake, weight and dietetic goals and ensure vitamins are included in any enteral or parenteral nutrition plan.
Assess alcohol withdrawal severity, seizures, sedation and respiratory rate separately from the Wernicke neurological examination.
For suspected Korsakoff syndrome, reassess memory and real-world function after weeks and months of abstinence and medical stability.
Confirm discharge thiamine supply, alcohol-service contact, accommodation safety and capacity or safeguarding actions rather than relying on verbal recall alone.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

The triad is insensitive

Waiting for confusion, ophthalmoplegia and ataxia to coexist misses many patients and allows a reversible biochemical lesion to become structural injury.

Fluency can conceal amnesia

A person with Korsakoff syndrome may converse socially yet forget the meeting, plan or clinician within minutes.

Confabulation is not deceit

Inaccurate narratives arise from disordered memory monitoring and are often believed by the speaker, changing how staff should communicate and assess risk.

MRI supports but cannot veto

Characteristic thalamic and mammillary changes increase confidence, but normal imaging is common enough that treatment remains a clinical decision.

Glucose is not withheld

A hypoglycaemic patient needs immediate carbohydrate; the safe principle is to give thiamine promptly before or concurrently, not to prolong neuroglycopenia.

More than one delirium can coexist

Withdrawal, sepsis, liver failure, subdural bleeding and Wernicke disease may all contribute, so response to one treatment does not exclude the others.

11Common pitfallsFrequent interpretation and management errors.

01
Do not wait for the complete classic triad or a serum thiamine result before treating a high-risk clinical presentation.
02
Do not use oral thiamine alone as initial treatment for suspected Wernicke encephalopathy.
03
Do not withhold emergency glucose from a hypoglycaemic patient while waiting for an intravenous vitamin preparation.
04
Do not call all confusion in alcohol dependence withdrawal or hepatic encephalopathy without assessing ocular and gait signs and nutrition.
05
Do not forget head injury, subdural bleeding, infection and stroke when focal signs or reduced consciousness occur.
06
Do not declare memory impairment permanent during intoxication, active delirium or the first days of withdrawal.
07
Do not discharge a person with profound new-learning difficulty using verbal instructions alone or without capacity and safeguarding review.