What is the full inpatient workup for a patient presenting with encephalopathy?

Full Inpatient Workup for Encephalopathy

The comprehensive inpatient workup for encephalopathy should include neuroimaging (preferably MRI), lumbar puncture, EEG, and extensive laboratory testing to identify the underlying cause, while initiating empiric treatment for potentially reversible etiologies. 1

Initial Assessment

Neurological Evaluation

• Complete neurological examination focusing on:
  • Level of consciousness
  • Focal neurological deficits
  • Presence of seizures or myoclonus
  • Movement disorders
  • Behavioral and personality changes
  • Neck stiffness

Neuroimaging

• MRI of brain with and without contrast (preferred) 2
  • Include pituitary protocol if indicated
  • Assess for:
    • Bilateral limbic encephalitis
    • Cortical/subcortical changes
    • Striatal, diencephalic, or brainstem involvement
    • Evidence of demyelination
    • Meningeal enhancement
• CT scan if MRI is contraindicated or unavailable 1

Lumbar Puncture

• Measure opening pressure 2
• CSF analysis:
  • Cell count and differential
  • Protein and glucose levels
  • Gram stain and culture
  • Viral PCRs (HSV, other viruses based on clinical suspicion)
  • Oligoclonal bands
  • Autoimmune encephalopathy panel
  • Paraneoplastic antibody panel
  • Cytology 2, 1

Electroencephalography (EEG)

• Evaluate for:
  • Subclinical seizures
  • Encephalopathic changes
  • Specific patterns (triphasic waves, generalized slowing) 2, 1, 3

Laboratory Workup

Basic Metabolic Panel

• Comprehensive chemistry panel
• Complete blood count
• Liver function tests
• Blood glucose
• Electrolytes
• Renal function tests 2, 1

Inflammatory Markers

• Erythrocyte sedimentation rate (ESR)
• C-reactive protein (CRP) 2

Endocrine Assessment

• Morning cortisol and ACTH
• Thyroid panel (TSH, free T4, TPO, thyroglobulin) 2

Autoimmune Workup

• Antinuclear antibody (ANA)
• Anti-neutrophil cytoplasmic antibodies (ANCA)
• Ro/La antibodies
• Aquaporin-4 IgG
• Myelin oligodendrocyte glycoprotein (MOG) antibodies 2

Infectious Disease Testing

• Blood cultures
• HIV testing
• Rapid plasma reagin (RPR) for syphilis
• Viral hepatitis panel 2, 1

Toxicology

• Urine and serum drug screens
• Heavy metal screening if clinically indicated 1, 4

Specific Testing Based on Clinical Suspicion

For Hepatic Encephalopathy

• Ammonia levels
• Liver function tests
• Coagulation profile 2, 5

For Autoimmune Encephalitis

• CSF and serum autoimmune encephalitis panels
• Anti-NMDA receptor antibodies
• Anti-LGI1, CASPR2, AMPA, GABA antibodies 2

For Paraneoplastic Syndromes

• Paraneoplastic antibody panels (anti-Hu, anti-CRMP5-CV2)
• Tumor markers
• Consider whole-body imaging (CT chest/abdomen/pelvis) 2

For Metabolic Encephalopathy

• Blood gases
• Lactate
• Plasma ketones
• Plasma amino acids
• Urinary organic acids 4

For Sepsis-Associated Encephalopathy

• Blood cultures
• Procalcitonin
• Lactate
• Source-specific cultures 3

Treatment Initiation During Workup

Empiric Therapy

• Intravenous acyclovir (10 mg/kg every 8 hours) if viral encephalitis is suspected 2, 1
• Empiric antibiotics if bacterial infection is suspected
• Thiamine administration before glucose in suspected Wernicke's encephalopathy 1
• Correction of obvious metabolic derangements 1

Seizure Management

• Anticonvulsants for clinical or subclinical seizures 1, 6

Supportive Care

• Airway protection if decreased level of consciousness
• Maintenance of adequate cerebral perfusion pressure
• Correction of electrolyte abnormalities 1

Special Considerations

For Immune Checkpoint Inhibitor-Related Encephalitis

• Hold immune checkpoint inhibitor therapy
• Consider high-dose corticosteroids (methylprednisolone 1-2 mg/kg/day)
• For severe cases: pulse steroids (methylprednisolone 1g IV daily for 3-5 days)
• Consider IVIG (2 g/kg over 5 days) or plasmapheresis for severe cases 2

For Hepatic Encephalopathy

• Lactulose administration
• Consider rifaximin as adjunctive therapy
• Protein restriction initially, with gradual increase 2, 5

Common Pitfalls to Avoid

• Delaying empiric treatment while awaiting diagnostic results 1
• Missing metabolic causes of encephalopathy 1, 4
• Performing lumbar puncture without checking for contraindications 1
• Overlooking drug toxicities or withdrawal syndromes 1
• Failing to recognize non-convulsive status epilepticus 1, 6
• Misdiagnosing encephalopathy in elderly patients due to atypical presentation 1

By following this comprehensive workup, clinicians can systematically evaluate patients with encephalopathy, identify the underlying cause, and initiate appropriate treatment to improve outcomes.