Comprehensive Inpatient Workup for Metabolic Encephalopathy
A comprehensive inpatient workup for metabolic encephalopathy must include laboratory testing, neuroimaging, identification of precipitating factors, and specialized testing based on clinical presentation to reduce morbidity and mortality. 1
Initial Assessment and Stabilization
Mental Status Evaluation
- Document level of consciousness using Glasgow Coma Scale
- Assess for asterixis, hyperreflexia, and other neurological findings
- Grade encephalopathy using West Haven criteria (for suspected hepatic encephalopathy):
- Grade I: Mild confusion, impaired attention, irritability
- Grade II: Lethargy, disorientation, inappropriate behavior
- Grade III: Somnolence, confusion, responsive to stimuli
- Grade IV: Coma, unresponsive 2
Essential Laboratory Testing
- Complete blood count
- Comprehensive metabolic panel (including electrolytes, renal and liver function)
- Coagulation studies (PT/INR, PTT)
- Arterial blood gas analysis
- Ammonia levels (particularly for suspected hepatic encephalopathy)
- Blood glucose
- Thyroid function tests
- Toxicology screen (including alcohol level)
- Heavy metal screening when indicated
- Vitamin levels (B12, folate, thiamine)
- HIV testing if risk factors present 1
Neuroimaging
- Brain CT or MRI to rule out structural causes and assess for cerebral edema
- CT should be performed before lumbar puncture if there are clinical contraindications 2, 1
Cerebrospinal Fluid Analysis
- Lumbar puncture (if no contraindications)
- Measure opening pressure
- CSF analysis: cell count, protein, glucose (with serum glucose)
- CSF culture and sensitivity
- CSF PCR for viral pathogens
- CSF lactate
- Consider oligoclonal bands 2
Specialized Testing
- Electroencephalography (EEG) - particularly valuable for:
- Unexplained altered mental status
- Suspected non-convulsive status epilepticus
- Monitoring of encephalopathy severity 2
- Psychometric tests for subtle hepatic encephalopathy:
- Psychometric Hepatic Encephalopathy Score (PHES)
- Critical Flicker Frequency (CFF)
- Continuous Reaction Time (CRT) test
- Inhibitory Control Test (ICT)
- Stroop test 2
Identification of Precipitating Factors
Systematic search for common precipitating factors:
Hepatic-Related
- Gastrointestinal bleeding (endoscopy, rectal exam)
- Infection (cultures, chest X-ray, urinalysis)
- Constipation (abdominal X-ray)
- Excessive protein intake
- Medication effects (particularly sedatives, opioids)
- Dehydration or volume overload 2, 1
Other Metabolic Causes
- Electrolyte disturbances (hyponatremia, hypokalemia)
- Hypoglycemia or hyperglycemia
- Hypoxia (pulse oximetry, arterial blood gas)
- Uremia (BUN, creatinine)
- Thiamine deficiency (Wernicke's encephalopathy)
- Adrenal insufficiency (cortisol level) 1, 3
Infectious Causes
- Sepsis (blood cultures, inflammatory markers)
- Meningitis/encephalitis (CSF analysis)
- Systemic infection (cultures, imaging) 2, 1
Toxic Causes
- Medication review (particularly benzodiazepines, opioids)
- Alcohol withdrawal or intoxication
- Illicit drug use
- Toxin exposure 1, 4
Management Considerations
Hepatic Encephalopathy Management
- Lactulose: First-line therapy (25 mL orally every 12 hours, titrated to achieve 2-3 soft bowel movements daily)
- Rifaximin: Add-on therapy (550 mg twice daily) for reducing recurrence risk
- Daily assessment of mental status
- Monitor serum creatinine, electrolytes, and ammonia levels 1
Critical Care Management
- Airway protection (intubation for Grade III/IV encephalopathy)
- Careful sedation management (avoid benzodiazepines if possible)
- Head elevation at 30 degrees for suspected increased intracranial pressure
- Nutritional support (enteral feeding when possible)
- Treatment of seizures if present 2
Monitoring and Follow-up
- Serial neurological examinations
- Follow-up laboratory testing based on underlying etiology
- Repeat neuroimaging if clinical deterioration occurs 1
Special Considerations
- Ammonia levels correlate poorly with hepatic encephalopathy severity and should not be used in isolation for diagnosis
- Consider liver transplantation evaluation for patients with recurrent or persistent hepatic encephalopathy
- Patients with minimal or covert hepatic encephalopathy may have normal clinical examination but abnormal psychometric testing 1
The workup should be tailored based on clinical presentation, with a focus on identifying and treating the underlying cause while providing appropriate supportive care to reduce morbidity and mortality.