Differential Diagnosis: Acute Alcohol Intoxication vs. Delirium vs. Toxic-Metabolic Encephalopathy
The constellation of symptoms you describe—nausea, confusion, slurred speech, disorientation, drowsiness, fatigue, lack of coordination, poor judgment, reduced inhibition, mood swings, flushed face, and pressured speech—is most consistent with acute alcohol intoxication, though delirium and toxic-metabolic encephalopathy must be urgently excluded as they represent medical emergencies. 1, 2
Primary Diagnostic Consideration: Acute Alcohol Intoxication
The symptom cluster strongly suggests acute alcohol intoxication, which presents with:
- Slurred speech (dysarthria), lack of coordination (ataxia), and drowsiness are classic CNS depressant effects 3, 4, 2
- Reduced inhibition, poor judgment, mood swings, and flushed face reflect alcohol's disinhibitory effects on frontal lobe function 2, 5
- Pressured speech, humming or grunting may represent paradoxical excitation or mixed intoxication 2
- Acute alcohol intoxication accounts for a significant proportion of altered mental status presentations in emergency settings 2, 5
Critical Pitfall
50% of patients with acute alcohol intoxication deny or downplay their alcohol consumption, making blood alcohol concentration (BAC) measurement essential rather than relying on patient history alone 5
Life-Threatening Alternative: Delirium
Delirium is a medical emergency with twice the mortality if missed, and must be actively excluded 1. Key distinguishing features include:
- Acute onset over hours to days with fluctuating course (symptoms wax and wane throughout the day with possible lucid intervals) 1
- Inattention as cardinal feature (inability to focus, maintain, or shift attention) 1
- Altered level of consciousness (not just behavioral changes) 1
- Disorganized thinking (rambling, irrelevant conversation, unclear flow of ideas) 1
When to Suspect Delirium Over Intoxication
- Symptoms persist beyond expected timeframe for substance clearance 1, 6
- Presence of underlying medical illness, recent surgery, or hospitalization 1
- Patient is elderly or has pre-existing cognitive impairment 1
- Fever, infection symptoms, or metabolic derangements present 1
Other Critical Differentials
Toxic-Metabolic Encephalopathy
46% of patients with apparent psychiatric symptoms have underlying medical illnesses directly causing their presentation 7. Consider:
- Medication-induced causes: Benzodiazepines cause identical symptoms (drowsiness, slurred speech, ataxia, confusion) 3, 4
- Metabolic disturbances: Hypoglycemia, hyponatremia, hyperammonemia, uremia 8, 9, 10
- Vitamin B12 deficiency: Can present with organic mental disorders, atypical psychiatric symptoms, and fluctuating symptomatology, particularly in elderly, vegetarians, alcoholics, or those with malabsorption 11
Stroke Mimic
Alcohol intoxication mimics posterior circulation stroke with shared symptoms of dysarthria, gait disturbances, and altered mental status 5. However:
- Stroke typically lacks the global disinhibition and mood changes seen here 5
- Flushed face and reduced inhibition favor intoxication 2
Diagnostic Algorithm
Step 1: Immediate Assessment
- Measure blood alcohol concentration (BAC) regardless of patient's reported alcohol use 5
- Check fingerstick glucose immediately to exclude hypoglycemia 1, 7
- Assess for delirium using Confusion Assessment Method (CAM): acute onset, fluctuating course, inattention, disorganized thinking 1
Step 2: Targeted History from Collateral Source
Since patient reliability is compromised 5:
- Timing: Acute (hours) suggests intoxication; subacute (days) suggests delirium or metabolic cause 1
- Fluctuation: Waxing/waning throughout day strongly suggests delirium 1
- Medication review: Complete list including over-the-counter drugs, benzodiazepines, anticholinergics 7, 3, 4
- Baseline cognition: Pre-existing dementia increases delirium risk 1
Step 3: Physical Examination Focus
- Vital signs: Fever suggests infection-triggered delirium 1
- Neurological exam: Focal deficits suggest stroke; symmetric findings favor metabolic/toxic cause 1, 7
- Asterixis or myoclonus: Suggests metabolic encephalopathy over intoxication 1
- Signs of chronic liver disease: Suggests hepatic encephalopathy 6
Step 4: Selective Laboratory Testing
Do not order routine screening labs without clinical indication as false positives lead to unnecessary workups 7. Order only if clinically indicated:
- Basic metabolic panel: If dehydration, renal dysfunction, or electrolyte disturbance suspected 7, 8
- Ammonia level: If cirrhosis present (normal ammonia in cirrhotic patient with delirium mandates search for other causes) 6
- Urinalysis and culture: If infection suspected 1
- Vitamin B12 and methylmalonic acid: If risk factors present (elderly, vegetarian, alcoholic, malabsorption) 11
Step 5: Neuroimaging Decision
Brain imaging (CT or MRI) is indicated when 1, 6:
- Diagnostic doubt exists after initial workup
- Focal neurological signs present
- No response to treatment of presumed cause
- New onset seizures occurred
- Concern for structural lesion (trauma, stroke, mass)
Management Approach
If Acute Alcohol Intoxication Confirmed
- Supportive care with observation in safe environment during recovery phase 2
- Monitor for complications of chronic alcoholism (Wernicke's encephalopathy, withdrawal) 2
- Serial reassessment to ensure symptom resolution matches expected BAC clearance 2, 5
If Delirium Identified
- Treat underlying cause immediately (infection, metabolic derangement, medication toxicity) 1, 6
- Non-pharmacological interventions first: Reorientation, cognitive stimulation, sleep hygiene 6
- Pharmacological management only if severe: Antipsychotics (quetiapine, olanzapam, haloperidol) for agitation; avoid benzodiazepines unless alcohol withdrawal 6