Autoimmune Encephalitis

Epidemiology

• Annual incidence of encephalitis: 2/3 per 100,000 ha (Europe)
• 40% infectious / 40% unknown / 20% autoimmune
  • 4% anti-NMDA receptor;
  • 3% anti-VGKC complex (LGl1 and CASPR2);
  • Anti-GABA receptor – the majority of limbic encephalitis cases in patients with small-cell lung cancer.

Immunological Mechanisms

Antibody-associated encephalitis is divided into two groups:

• Anti-neuronal surface antibodies (ANSA)
  • The pathogenic mechanism involves a direct effect on antigens;
  • Antigen-dependent decrease in titer at the synaptic cleft;
  • Intrathecal antibody production;
  • B cells and plasma cells;
  • e.g., NMDAR; VGKC complex; AMPAR; GABAR; DPPX.

Anti-onconeuronal antibodies (intracellular)

• Classic Paraneoplastic Neurological Syndromes;
• Worse prognosis
• Pathogenic mechanisms mediated by cytotoxic T cells and complement activation.
• e.g., HU, Yo, Ri, CV2, Ma2, Ampifisina, Tr

Clinical Spectrum

Encephalitis associated with ANSA almost always presents with a clinical picture of limbic encephalitis:

• Short-term memory loss
• Epileptic seizures
• Behavioral disturbances
• Psychiatric symptoms

Diagnosis of Autoimmune Encephalitis

ANSA - Anti-neuronal surface antibodies

Antibodies directed against antigenic targets located on the surface of neuronal cells, associated with autoimmune encephalitis. The clinical features of the various forms of encephalitis associated with the presence of these ANSA often overlap; therefore, it is recommended that ANSA testing be performed in parallel with testing for anti-paraneoplastic syndrome antibodies.

Download the brochure