Encephalitis: trigger, symptoms, diagnosis, prognosis - NetDoktor - Diseases - 2021



The encephalitis is a brain infection, which in most cases is caused by viruses. If encephalitis affects not only the brain, but also the meninges, it is meningoencephalitis. Particularly at risk of developing encephalitis are children and young adults as well as persons with a weakened immune system. Read all important information about encephalitis here.

ICD codes for this disease: ICD codes are internationally valid medical diagnosis codes. They are found e.g. in medical reports or on incapacity certificates. G05G04ArtikelübersichtEnzephalitis

  • description
  • symptoms
  • Causes and risk factors
  • Examinations and diagnosis
  • treatment
  • Disease course and prognosis

Encephalitis: description

encephalitis is the medical term for encephalitis. This is usually caused by viruses. However, encephalitis can also be caused by other pathogens such as bacteria, unicellular organisms or worms, or by a defective immune response.

Since untreated encephalitis is associated with high mortality, it is important to begin treatment as early as possible in the hospital. Since at the beginning of the disease often can not be determined which pathogen is the cause, various drugs are given simultaneously. Once the pathogen has been detected by laboratory tests, only those drugs will be administered that are directed against this particular pathogen. In addition, the symptoms themselves are treated, such as pain or seizures with appropriate preparations. With timely treatment in many cases a cure of encephalitis is possible.

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Encephalitis: symptoms

Depending on the pathogens, the symptoms of encephalitis very different. This is because different pathogens preferentially infect certain brain regions. In viral encephalitis, there are general, flu-like symptoms such as fever, headache, fatigue, muscle aches and nausea. Only then do the specific symptoms of encephalitis develop. Symptoms are:

  • Awareness disorders (eg unconsciousness or confusion)
  • sudden impairment of concentration and memory
  • Behavioral changes (eg conspicuous mood swings, hallucinations, paranoia or disorientation [organic psychosyndrome])
  • Vomit
  • neurological deficits (eg disorders of speech and speech, paralysis of individual extremities or eye muscles)
  • seizures
  • simultaneous irritation of the meninges (meningoencephalitis): neck and / or back stiffness (meningism)

Complications that occur at a encephalitis may be a persistent seizure (status epilepticus) or a swelling of the brain (cerebral edema).

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Encephalitis: causes and risk factors

The encephalitis is usually the result of a viral infection. One differentiates between the primary and secondary form. In the primary form, the viruses cause inflammation directly in the brain. In the secondary form, the body's own immune system derailed in response to a viral infection in the body and subsequently attacked the brain (autoimmune reaction). In the process, structures (autoantibodies) that are directed against specific components in the brain are formed by the body.

Encephalitis is often triggered in Germany by the following viruses:

  • Herpes simplex virus
  • Varicella-zoster virus
  • Epstein-Barr virus
  • measles virus
  • mumps virus
  • rubella virus
  • enteroviruses
  • TBE (Fruhsommer-Meningo-enzephalitis) viruses

There are other viruses worldwide that are considered to be the cause of encephalitis:

  • Lyssaviruses (rabies)
  • West Nile Virus
  • Arboviruses (Japanese Encephalitis)

The TBE viruses (causative agent of early summer meningoencephalitis) are transmitted to humans through tick bites. Animal bites (eg of bats) can infect you with rabies.

In addition to the viruses, there are other triggers of encephalitis. These include various bacteria (eg the causative agents of syphilis, tuberculosis or Lyme disease), unicellular organisms (eg the pathogens of toxoplasmosis), parasites (eg worms), fungi or autoimmune diseases (eg. Multiple sclerosis).

Encephalitis, the cause of which is still unclear, is the so-called European sleeping sickness (encephalitis lethargica). It occurred mainly between the years 1917 to 1928 worldwide and may later lead to Parkinson's disease.

Particularly at risk of developing encephalitis are children and young adults. In addition, individuals with weakened immune systems - such as those infected with HIV - have a greater risk of developing encephalitis. Since some of the viruses mentioned do not occur in our latitudes, long-haul travelers are also at greater risk.

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Encephalitis: examinations and diagnosis

To diagnose encephalitis, the doctor asks about the symptoms and the medical history. Information on general diseases, viral infections or even tick bites help with the diagnosis. In addition to questioning the patient, the doctor attempts to obtain a second description by family members. This is necessary because people with encephalitis are often limited in their perception, thinking and communication skills. Other useful information relates to recent vacation travel, contact with livestock or other people with encephalitis.

The next step is an accurate physical and neurological examination in which the physician tests posture, motor skills, and various nerve-directed responses, among other things. In addition to the described symptoms, skin symptoms or disturbances of the water balance in the body sometimes occur.

If the doctor suspects encephalitis, he also examines the patient's blood and cerebrospinal fluid (cerebrospinal fluid) for signs of inflammation (changes in CSF, pathogen or antibody detection). In order to detect the type of pathogen, the so-called polymerase chain reaction (PCR) is suitable; she identifies even the smallest amounts of virus. The doctor gains a sample of the liquor by means of a lumbar puncture. However, many pathogens of encephalitis can not be detected or only with great effort and often only after days or weeks. For example, in the acute phase of the disease, no pathogens are usually detectable in the CSF. Therefore, at first often only the symptoms can show the way to diagnose encephalitis and its trigger.

As a rule, if there is suspicion of encephalitis, the doctor will immediately perform a computed tomography (CT) to rule out other brain diseases (eg cerebral hemorrhage or brain abscess). Magnetic resonance imaging (MRI) is also possible.

The brain abscess differs from the encephalitis in that it is mostly caused by (other) bacteria. It is spatially limited and consists of a collection of pus, which is surrounded by a connective tissue capsule.

In addition - especially if the encephalitis caused by herpesviruses - an electroencephalography (EEG) performed. Although this can give an indication of the pathogen only in exceptional cases, but make it visible at an early stage, whether and how the inflammation affects the brain function.