18.2 Alcohol & Sedative Withdrawal, Wernicke Encephalopathy & Drug-Induced Encephalopathy
Key Takeaways
Symptom-triggered benzodiazepine dosing using a validated scale shortens treatment and lowers total dose compared with fixed-schedule dosing in alcohol withdrawal.
Phenobarbital and propofol act at the GABA-A receptor independent of benzodiazepine binding and are the escalation options for benzodiazepine-refractory delirium tremens.
Dexmedetomidine controls autonomic hyperactivity in alcohol withdrawal but does not prevent seizures, so it is an adjunct rather than a substitute for GABAergic therapy.
Wernicke encephalopathy is treated with thiamine 500 mg intravenously three times daily for 2 to 3 days, given before any glucose load.
ICANS from CAR-T therapy is graded by the ICE score and treated with corticosteroids, with tocilizumab reserved for concurrent cytokine release syndrome because it does not penetrate the central nervous system well.
Alcohol Withdrawal: Timeline and Severity
| Time after the last drink | Syndrome |
|---|---|
| 6 to 24 hours | Minor withdrawal: tremor, anxiety, sweating, tachycardia, hypertension, nausea; sensorium intact |
| 12 to 48 hours | Withdrawal seizures, usually generalized tonic-clonic, often in a brief flurry |
| 12 to 48 hours | Alcoholic hallucinosis: visual or tactile hallucinations with a clear sensorium |
| 48 to 96 hours | Delirium tremens: delirium with disorientation, severe autonomic hyperactivity, hyperthermia, and hallucinations; untreated mortality is substantial |
Risk factors for severe withdrawal: prior delirium tremens or withdrawal seizures, a high blood alcohol level despite being alert, a long heavy-drinking history, concurrent illness or surgery, older age, and electrolyte derangement. The PAWSS score screens for risk at admission.
Treatment
- Benzodiazepines are first-line because they are the only class shown to reduce seizures and delirium.
- Symptom-triggered dosing using a validated scale (CIWA-Ar, or a sedation-agitation-based protocol in intubated patients) shortens duration and lowers total dose compared with fixed schedules. Fixed schedules remain useful where monitoring is limited or the patient cannot be assessed.
- Diazepam and chlordiazepoxide have long-acting active metabolites that self-taper; lorazepam is preferred with significant liver disease because it is glucuronidated without active metabolites.
- Escalate quickly in severe withdrawal: repeated intravenous diazepam 10 mg doses, doubling as needed.
- Benzodiazepine-refractory delirium tremens: patients requiring very large cumulative doses need an agent acting at a different site on the GABA-A receptor.
- Phenobarbital: long half-life, predictable, effective; watch for respiratory depression and hypotension.
- Propofol: requires intubation; it also acts at GABA-A independent of the benzodiazepine site.
- Ketamine is used as an adjunct to reduce benzodiazepine requirements.
- Dexmedetomidine controls autonomic hyperactivity and agitation but does not prevent seizures or treat the underlying GABA deficit, so it is an adjunct only.
- Avoid beta-blockers or clonidine as monotherapy: they blunt the vital-sign markers while the patient remains at risk of seizures and delirium.
- Antipsychotics are adjuncts for hallucinations and agitation and lower the seizure threshold; they never replace GABAergic therapy.
- Supportive care: thiamine before glucose, folate, multivitamins, and aggressive replacement of magnesium, potassium, and phosphate (watch for refeeding syndrome). Treat concurrent illness, which commonly precipitates severe withdrawal, and screen for occult infection, trauma, pancreatitis, and subdural hematoma.
- Sedative-hypnotic withdrawal (benzodiazepines, barbiturates, baclofen, gamma-hydroxybutyrate) looks similar and is treated by substituting and tapering a long-acting agent of the same class. Baclofen withdrawal after pump failure causes severe rigidity, fever, and rhabdomyolysis that mimics neuroleptic malignant syndrome; restore baclofen urgently.
Wernicke Encephalopathy and Korsakoff Syndrome
- Classic triad: encephalopathy, oculomotor abnormalities (nystagmus, bilateral abducens palsy, conjugate gaze palsy), and gait ataxia. All three are present in only a minority, so treat on suspicion.
- At-risk patients: alcohol use disorder, hyperemesis gravidarum, bariatric surgery, prolonged parenteral nutrition without vitamins, malignancy and chemotherapy, dialysis, and refeeding after starvation.
- MRI: symmetric signal change in the mammillary bodies, medial thalami, periaqueductal gray, and tectal plate.
- Treatment: thiamine 500 mg IV three times daily for 2 to 3 days, then 250 mg daily for several days, then oral supplementation. Give thiamine before glucose, because a carbohydrate load consumes the remaining thiamine and can precipitate or worsen the syndrome. Replace magnesium, which is a cofactor for thiamine-dependent enzymes; untreated hypomagnesemia causes thiamine refractoriness.
- Untreated Wernicke encephalopathy progresses to Korsakoff syndrome: irreversible anterograde and retrograde amnesia with confabulation.
Drug-Induced and Metabolic Encephalopathy
| Agent or cause | Signature | Management |
|---|---|---|
| Cefepime (and other beta-lactams) | Myoclonus, encephalopathy, nonconvulsive status; kidney impairment with unadjusted dosing | Stop or dose-adjust; dialysis if severe |
| Ifosfamide | Encephalopathy within 1 to 2 days of infusion, sometimes with seizures | Stop the infusion; methylene blue is used, with thiamine as an adjunct |
| Calcineurin inhibitors (tacrolimus, cyclosporine) | Tremor, seizures, PRES | Reduce the level or switch agents |
| Chemotherapy-related | Methotrexate (stroke-like syndrome, treated with leucovorin and aminophylline), cytarabine (cerebellar toxicity), 5-fluorouracil (with DPD deficiency), cisplatin | Stop the drug; agent-specific measures |
| Serotonin syndrome and neuroleptic malignant syndrome | Hyperthermia with clonus and hyperreflexia, or with lead-pipe rigidity | See the adverse drug reaction section |
| Opioid and sedative accumulation | Reduced level of arousal with miosis; prolonged with kidney or liver failure and obesity | Dose interruption, naloxone when appropriate |
| Lithium, valproate, and antiepileptic toxicity | Tremor, ataxia, encephalopathy, hyperammonemia with valproate | Levels, drug withdrawal, dialysis for lithium |
| Serotonergic antibiotics | Linezolid with SSRIs | Stop and support |
| Uremia, hepatic failure, hyponatremia, hypercapnia, hypoglycemia, hypothyroidism, hypercalcemia | Metabolic patterns | Correct the derangement |
Important
Any ICU patient with unexplained encephalopathy needs an EEG: nonconvulsive status epilepticus accounts for a meaningful share of unexplained coma and is otherwise invisible.
Neurotoxicity of Immune Effector Cell Therapy (ICANS)
- Setting: CAR-T cell therapy and bispecific T-cell engagers, usually within 1 to 3 weeks and typically after cytokine release syndrome begins.
- Presentation: expressive aphasia and dysgraphia first, then confusion, tremor, somnolence, seizures, and in severe cases cerebral edema.
- Grading: the ICE score (immune effector cell-associated encephalopathy) tests orientation, naming, following commands, writing, and attention out of 10 points; grading also uses level of consciousness, seizures, motor findings, and raised intracranial pressure or edema.
- Management:
- Corticosteroids (dexamethasone, escalating to high-dose methylprednisolone for grade 3 or 4) are the mainstay.
- Tocilizumab treats concurrent cytokine release syndrome but penetrates the central nervous system poorly and does not treat ICANS itself; it may even raise CSF IL-6.
- Antiseizure prophylaxis (commonly levetiracetam), EEG monitoring, aspiration precautions, and treatment of cerebral edema.
- Hold oral intake in patients with aphasia or reduced consciousness; many require intubation for airway protection.
- Related entities: immune checkpoint inhibitor encephalitis (treated with steroids and drug discontinuation), and hemophagocytic lymphohistiocytosis with neurologic involvement.
A 52-year-old man with heavy daily alcohol use is admitted after a fall. Sixty hours later he is disoriented and hallucinating, with a heart rate of 136 bpm, blood pressure of 178/98 mmHg, and temperature of 38.3 °C. He has received 180 mg of intravenous diazepam over 6 hours with minimal effect. What is the most appropriate next step?
Start intravenous phenobarbital, with propofol and intubation if control is still not achieved
Start a dexmedetomidine infusion as the primary therapy and stop benzodiazepines
Start intravenous metoprolol and clonidine to control the autonomic signs
Add scheduled haloperidol as monotherapy for the hallucinations
A 41-year-old woman with 10 weeks of hyperemesis gravidarum is admitted with confusion, horizontal nystagmus, and ataxia. Her glucose is 58 mg/dL. Which sequence is most appropriate?
Give dextrose 50% immediately, then thiamine 100 mg intravenously once daily
Give thiamine 500 mg intravenously, then dextrose, and replace magnesium
Give oral thiamine 100 mg daily and treat the hypoglycemia with enteral feeding
Give dexamethasone and arrange MRI before any vitamin replacement
Nine days after CAR-T cell infusion for refractory lymphoma, a 57-year-old man becomes inattentive with expressive aphasia and an ICE score of 4. He is afebrile and normotensive, with no evidence of active cytokine release syndrome. Which treatment is most appropriate?
Tocilizumab alone, because it is the standard therapy for neurotoxicity
Corticosteroids with antiseizure prophylaxis and EEG monitoring
Plasma exchange to remove circulating CAR-T cells
Observation alone, because aphasia after CAR-T therapy resolves without treatment
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