What is it about ?
Encephalitis is an acute (that is, sudden) inflammation of brain tissue. Usually the meninges, which are in close contact with brain tissue, are also inflamed (meningitis).
Usually the cause of the disease is an infection caused by a virus, and more rarely by bacteria. The possible causes are:
- herpes simplex virus
- virus that causes chickenpox and shingles (varicella zoster virus)
- the virus that is transmitted after a tick bite (tick-borne encephalitis),
- The bacteria Borrelia causing Lyme disease, which is spread after an infected tick bite
- Epstein-Barr virus (trigger of infectious mononucleosis)
- viruses that cause respiratory infections, such as adenoviruses, influenza viruses (influenza viruses)
- sexually transmitted diseases (STDs), such as HIV infection, syphilis, Chlamydia infection
- …
What is its frequency?
We do not have precise figures for Belgium. In the Netherlands, encephalitis occurs in about 2 to 4 in 100,000 people per year. By far the most common causative agent is herpes simplex virus type 1. However, there is no link between the appearance of a cold sore (cold sore) and encephalitis.
How to recognize it?
On the one hand, there are symptoms linked to the infection, and on the other hand, signs of damage to the brain tissue.
The infection usually causes mild flu-like symptoms, such as sudden headaches, joint and muscle pain, fatigue, and fever.
Damage to brain tissue can cause the following symptoms:
- decreased state of consciousness or confusion,
- changes in personality and / or intellectual abilities,
- convulsions,
- difficulties in speaking,
- paralysis on one side of the body,
- vision problem or trouble with eye movement
- inability to lift the corners of the mouth,
- ….
When the meninges are also affected (meningoencephalitis), there is stiffness in the neck. This stiffness prevents the chin from being brought to the chest. But this sign can also be absent.
How is the diagnosis made?
The diagnosis of encephalitis is mainly based on the symptoms and signs that the brain tissue is functioning less well. The doctor will also ask you questions to find out how you were exposed to the pathogen (for example while traveling abroad).
As this is a serious and complex illness, the doctor will send you to the hospital for further examinations. A lumbar puncture and a blood test will usually be performed there. Lumbar puncture and cerebrospinal fluid analysis can see if it is a viral or bacterial infection.
In some types of encephalitis, specific antibodies are also found in the blood. If the disease has already progressed for several days, abnormalities may also be seen on a CT scan of the brain.
What can the doctor do?
Encephalitis is usually treated in the hospital. Bed rest is necessary. In addition, the cause is treated where possible.
In case of encephalitis caused by a virus, treatment with antiviral drugs is usually started, although it is not yet clear what the cause is. If the herpes virus is fought early, the chances of recovery increase.
Antibiotics are indicated if the encephalitis is caused by bacteria.
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