Well shielded from harmful influences, the “gray cells” lie in their solid bone shell. Nevertheless, some pathogens manage to overcome the numerous protective barriers and penetrate right into our control center. The immune system reacts with an inflammatory response, often with fatal consequences. Inflammation of the brain tissue is a serious disease that is not infrequently fatal. Its name is derived from “encephalon”, the Greek term for brain. Often there is simultaneous inflammation of the meninges or the spinal cord – this is then referred to as meningoencephalitis or encephalomyelitis.
Causes of encephalitis
Triggers are almost always pathogens, especially viruses. The elderly and children, as well as people with a weakened immune system, are particularly at risk. However, even in otherwise healthy individuals, concomitant encephalitis can occur as part of a general infection such as influenza, measles, or mumps infection (parainfectious encephalitis) or as a reaction of the immune system to a vaccination (postvaccinal encephalitis). Bacteria (e.g. meningococci, pneumococci) – and, even more rarely, parasites and fungi are also possible pathogens – usually as a result of blood poisoning or a poor immune situation, e.g. in AIDS patients. Particularly feared here are the cytomegalovirus and herpes virus, as well as cryptococci and toxoplasmas. Viruses (early summer meningoencephalitis = FSME) and bacteria (Lyme disease) can also be transmitted via a tick bite. More rarely, inflammation in the brain can be caused by other processes instead of pathogens, for example, in the context of multiple sclerosis or autoimmune diseases.
Symptoms of encephalitis
Whether tiny viruses, somewhat larger bacteria, or branching fungi have gained access to the brain, the consequences are basically the same. The immune system sends its defenses to the site to render the invaders harmless, resulting in swelling of the brain tissue. This, in turn, quickly has fatal consequences: Because of the tight, solid skull bone, the tissue doesn’t have many opportunities to spread. The intracranial pressure increases and severe headaches, nausea and vomiting occur. Later, disorders of consciousness, memory and orientation, confusion or hallucinations occur. Depending on where the pathogens have settled, functional deficits may become apparent. These include numbness, paralysis, visual and speech disorders, but also seizures. If the meninges are also affected, there is also neck stiffness. In addition, those affected usually have a high fever and feel very ill. Important: Affected persons must seek medical treatment as soon as possible. An ambulance should be called or an emergency room should be visited!
Diagnosis of encephalitis
The symptoms are usually so typical that the physician can very quickly make a tentative diagnosis, arrange for specific examinations, and initiate treatment. In particular, poisoning, which can cause very similar symptoms, must be ruled out. In addition to the physical examination, blood is taken, in which one can find signs of inflammation and pathogens or immune cells. It is important to examine the cerebrospinal fluid (CSF puncture), which can provide information about the type of inflammation. Imaging procedures such as magnetic resonance imaging or computer tomography can be used to detect brain swelling and abscesses (settlement of the pathogens) and to rule out other causes of the symptoms such as a hemorrhage or a tumor. In some cases, it is also necessary to look for another source of disease in the body, from where the pathogens move out and enter the brain. In cases of seizures, brain waves are measured by EEG.
Treatment of encephalitis
Treatment is started as soon as possible in the intensive care unit. Depending on the patient’s condition, treatment may include circulatory stabilization, pain-reducing and fever-reducing measures, ventilation, infusions, and/or placement of a catheter. In addition, a specific therapy is initiated to combat pathogens, whereby the physician selects the medications according to the type of germs, immune status and previous illnesses, among other factors. Antibiotics are administered for bacteria, antimycotics for fungi, and so-called virustatics for viruses. However, not all viruses can be combated with these drugs, so in some cases only general measures remain to combat symptoms and prevent complications.
Course and prognosis in encephalitis
It is difficult to make general statements about the course of encephalitis because it depends greatly on the type of pathogen and the general condition of the affected person, as well as on how quickly therapy was started. Estimates assume that in the case of TBE about 2 % of the ill persons die, in the case of encephalitis caused by the herpes virus still about 20 % despite specific therapy – in former times it was more than 80 %! It is not uncommon for the scars to cause permanent damage such as seizures or paralysis. Especially from this point of view, it is important to remember that vaccinations can be used to prevent a number of viral diseases that can cause brain inflammation, as well as some meningococci and pneumococci.
