What are the acute and chronic effects of alcohol on the central nervous system, and how should intoxication and withdrawal be managed?

Alcohol Effects on CNS

Alcohol causes acute CNS depression through GABA receptor activation and chronic neurotoxicity leading to cognitive impairment, cerebellar degeneration, peripheral neuropathy, and Wernicke-Korsakoff syndrome, with withdrawal potentially causing life-threatening seizures and delirium tremens that require immediate benzodiazepine treatment.

Acute CNS Effects

Intoxication

Alcohol acts as a CNS depressant by activating GABA receptors and inhibiting NMDA receptors 1. This produces:

• Impaired coordination and sluggish reflexes
• Emotional lability and altered judgment
• Cognitive impairment proportional to blood alcohol level
• Risk of acute encephalopathy, coma, and respiratory depression at high levels

Important caveat: Cognitive function, not a specific blood alcohol level, should determine when psychiatric evaluation can begin 2. There is no evidence-based threshold for "medical clearance" based solely on alcohol levels.

Withdrawal Syndrome (AWS)

AWS develops 6-24 hours after cessation in alcohol-dependent individuals due to sudden loss of GABA-mediated inhibition combined with upregulated NMDA excitatory activity 1. This creates dangerous CNS hyperexcitability.

Timeline and progression:

• 6-24 hours: Mild symptoms (tremors, tachycardia, hypertension, sweating, anxiety, nausea)
• 12-24 hours: Hallucinations (2-8% of patients)
• 12-48 hours: Withdrawal seizures (up to 15% of patients) - these are rebound phenomena from lowered seizure threshold, NOT epilepsy requiring anticonvulsants 3
• 72 hours (peak at 3-5 days): Delirium tremens (3-5% of patients) - altered mental status, disorientation, autonomic instability, with 50% mortality if untreated 1

Chronic CNS Effects

Structural and Functional Damage

Chronic alcohol causes irreversible neurologic injury through 4:

• Direct neurotoxicity
• Thiamine and other nutritional deficiencies
• Hepatic dysfunction
• Neuroinflammation

Clinical manifestations:

• Cerebellar degeneration: Progressive ataxia, gait instability
• Peripheral neuropathy: Sensory and motor deficits
• Cognitive-behavioral disorders: Dementia, executive dysfunction
• Wernicke-Korsakoff syndrome: Acute confusional state (Wernicke's) progressing to irreversible amnesia and confabulation (Korsakoff's)
• Myopathy: Muscle weakness and wasting

Management of Alcohol Withdrawal

Indications for Admission

Admit immediately if 3:

• Delirium tremens or seizures
• History of withdrawal seizures or delirium
• Severe AWS symptoms
• Significant medical or psychiatric comorbidities
• Advanced age, head trauma, liver failure, respiratory failure
• Failed outpatient management

Pharmacologic Treatment

Benzodiazepines are the gold standard 3, 5:

For most patients (long-acting preferred for seizure prevention):

• Chlordiazepoxide 25-100 mg PO every 4-6 hours
• Diazepam 5-10 mg PO/IV/IM every 6-8 hours

For patients with liver failure, advanced age, head trauma, respiratory failure, or obesity (intermediate-acting safer):

• Lorazepam 1-4 mg PO/IV/IM every 4-8 hours, starting at 6-12 mg/day total, then taper 3

Use symptom-triggered dosing rather than fixed schedules to prevent drug accumulation 6.

Critical Thiamine Administration

Give thiamine 100-300 mg/day to ALL patients with AWS 3:

• Prevents Wernicke encephalopathy
• Continue for 2-3 months after withdrawal resolution
• Critical: Administer thiamine BEFORE glucose-containing IV fluids, as glucose can precipitate acute thiamine deficiency 3
• If Wernicke encephalopathy present: increase to 100-500 mg/day for 12-24 weeks

Adjunctive Treatments

For agitation/hallucinations not controlled by benzodiazepines:

• Haloperidol 0.5-5 mg PO every 8-12 hours or 2-5 mg IM 3
• Use cautiously as adjunct only

Alternative agents (when benzodiazepines contraindicated):

• Carbamazepine 200 mg PO every 6-8 hours (effective for seizure prevention) 3
• Baclofen and topiramate show promise for both AWS and relapse prevention 5, 6

Supportive Care

• IV fluids for hydration
• Electrolyte replacement (especially magnesium)
• Comfortable, quiet environment
• Frequent vital sign monitoring 3

Long-Term Management

Abstinence is critical - it improves survival, prevents cirrhosis progression, reduces portal pressure, and reverses histologic damage 3, 7.

Pharmacotherapy for Abstinence Maintenance

Naltrexone or acamprosate reduce relapse risk when combined with counseling 7:

• Naltrexone: Avoid in severe liver disease due to hepatotoxicity risk 5
• Acamprosate: Safe in liver disease, reduces craving and withdrawal symptoms 7
• Baclofen: Only agent tested in cirrhotic patients, shows efficacy but needs confirmation 3, 6

Avoid disulfiram in severe liver disease due to hepatotoxicity 5.

Psychiatric Consultation

Mandatory for AWS patients 3 for:

• Evaluation and acute management
• Long-term abstinence planning
• Assessment of psychiatric comorbidities (anxiety, depression, schizophrenia are highly prevalent) 5

Key Clinical Pitfalls

1. Don't use CIWA-Ar for diagnosis - it's useful for severity assessment but can be falsely elevated in sepsis, hepatic encephalopathy, anxiety disorders 3

2. Don't treat withdrawal seizures with anticonvulsants - they're rebound phenomena, not epilepsy; benzodiazepines prevent recurrence 3

3. Don't delay thiamine - always give before glucose to prevent precipitating Wernicke's 3

4. Don't use benzodiazepines beyond 10-14 days - abuse potential is high in this population 6

5. Monitor for concurrent medical complications: dehydration, electrolyte imbalance, infection, GI bleeding, pancreatitis, hepatic encephalopathy 3