Types of Encephalitis

  • Types of Encephalitis

    Main types

    Infectious encephalitis (Acute Viral Encephalitis)
    Post-infectious encephalitis (Autoimmune)

    Types of Infectious encephalitis – in many cases the viral cause is not identified

    Herpes Simplex encephalitis
    West Nile encephalitis (or West Nile fever)
    Japanese encephalitis
    Tick borne encephalitis
    Mycoplasma encephalitis
    California encephalitis
    St Louis encephalitis
    Western equine encephalitis
    Eastern equine encephalitis
    Colorado tick fever

    Types of Post-infectious encephalitis (autoimmune) encephalitis
    Acute disseminated encephalitis (ADEM)
    Hashimoto’s encephalitis
    Encephalitis Lethargica
    Rasmussen’s encephalitis
    Paraneoplastic encephalitis
    Potassium channel antibody encephalitis

    Chronic types of encephalitis
    Subacute Sclerosing Panencephalitis
    Rubella Panencephalitis

    Types of encephalitis by area
    Brainstem encephalitis
    Limbic encephalitis
    Cerebellitis
    Meningoencephalitis

Encephalitis simply means inflammation of the brain.  It is usually caused by a viral infection but can also be caused by parasites, bacteria and fungi.  Inflammation of the brain can also result from metabolic disturbances, be a side effect of some drugs and a symptom of a type of cancer.

They are two mechanisms by which a viral infection can cause encephalitis:

  • Infectious encephalitis (Acute Viral Encephalitis)- invasion of the brain parenchyma (substance) by a virus, example herpes simplex encephalitis
  • Post-infectious encephalitis (Autoimmune) - inflammation triggered by the immune system, example is ADEM

A number of different viruses can cause encephalitis, examples include the herpes simplex virus (in the UK), japanese virus (in the far east), west nile virus (in Africa and North America) and tic-borne (in forested areas of Europe). Others include herpes simplex types 5 and 6 (in children), varicella-zoster virus (chicken pox), Enteroviruses (tummy bugs), Influenzaviruses, Measles, Mumps and Rubella. However in most cases in the UK the causative agent is not found.

Some types of encephalitis have very distinctive patterns and include Rasmussen’s encephalitis, Brain Stem Encephalitis, Hashimoto’s encephalitis and SSPE (Sub-Sclerosing Pan Encephalitis).

Acute Disseminated encephalomyelitis (ADEM) is also called post-infectious encephalitis or para-infectious encephalitis. Nerve cells themselves are not the major target of damage but rather their "electrical insulation coat" (myelin sheath) which results in abnormal brain function.

Last modified: 27/06/2006