anti-leucine-rich glioma inactivated 1 (LGI1) encephalitis

Etiology

• CSF antibody to leucine-rich glioma-inactivated protein 1 (LGI1)

Clinical manifestations

• confusion, psychosis, agitation, delusions, hallucinations
• hyponatremia
• drug-resistant seizures
  • may present as refractory temporal lobe epilepsy complicating convulsive status epilepticus

Laboratory

• LGI1 Ab in CSF
• oligoclonal bands in CSF (variable)
• serum sodium: hyponatremia

Diagnostic procedures

• electroencephalography (EEG): temporal lobe seizures

Radiology

• MRI neuroimaging
  • temporal lobe hyperintensity

Complications

• may be associated with cancer (10%), thymoma most common

Differential diagnosis

• anti-NMDA receptor encephalitis
• Herpes simplex encephalilitis

Management

• empiric IV acyclovir for Herpes simplex encephalitis until diagnosis is clarified
• immunosuppressive therapy:
  • combination of plasmapheresis, intravenous gamma-globulin & glucocorticoids
    • rituximab or cyclophosphamide for long-term therapy

More general terms

• paraneoplastic limbic encephalitis
• temporal lobe (psychomotor) epilepsy