Definition

Encephalitis: inflammation of the brain parenchyma

• Limbic encephalitis: inflammation of brain tissue that primarily affects the limbic system in the medial temporal lobes

• Cerebellitis: inflammation of the cerebellum

• Brainstem encephalitis: inflammation of the brain tissue that primarily affects the brainstem and adjacent regions

• Meningoencephalitis: concurrent inflammation of meninges (meningitis) and brain parenchyma (encephalitis)

Encephalomyelitis: concurrent inflammation of the brain (encephalitis) and spinal cord (myelitis)

Infectious encephalitis: inflammation of the brain parenchyma caused by pathogens

• Viral encephalitis: inflammation of the brain parenchyma caused by viruses (most common type of infectious encephalitis)

• Bacterial encephalitis: inflammation of the brain parenchyma caused by bacteria

• Other: fungal (e.g., Cryptococcus neoformans), parasitic (e.g., Naegleria fowleri)

Autoimmune encephalitis: inflammation of brain tissue mediated by autoimmune antibodies

• According to its association with neoplasms

  • Paraneoplastic encephalitis: mediated by antibodies targeted against intracellular and extracellular neuronal proteins

  • Non-paraneoplastic: idiopathic, postinfectious (e.g., acute disseminated encephalomyelitis, anti-NMDAR encephalitis post herpes simplex encephalitis infection)

• According to the targeted neuronal antigens

  • Intracellular antigens (commonly tumor-associated)

  • Surface antigens