What types of meningoencephalitis are there? | Meningoencephalitis

What types of meningoencephalitis are there?

Meningoencephalitis herpetica is the inflammation of the brain caused by Herpes simplex virus I. Approximately 90% of the population carries the Herpes simplex virus I and many have experienced it at least once through lip herpes. If a person is infected with the virus, they are lifelong carriers of the pathogen.

After the initial infection, it sometimes leads to the classic cold sore (Herpes labiales). After the acute infection has healed, the virus settles in the nerve node of a facial nerve (trigeminal nerve) and can be reactivated if the immune system is weakened. Meningoencephalitis herpetica occurs when the virus is reactivated and travels along the nerve fibers into the brain or when it re-enters the patient from outside.

This occurs via the nasal mucosa, through which it reaches the olfactory nerve (Nervus olfactorius). The olfactory nerve is a direct extension of the brain and allows the virus to infect the front and later also the lateral lobe. The classic symptoms of meningoencephalitis appear.

As focal symptoms, speech disorders, olfactory disorders and (focal) epileptic seizures dominate. Early summer meningoencephalitis (or TBE for short) is an inflammation of the brain and its membranes caused by a virus. This virus is usually transmitted from infected ticks to humans.

The disease often progresses completely asymptomatically. In one third of patients, only flu-like symptoms such as headache, aching limbs and fever initially occur. Typical for the course of the disease is that these symptoms then improve.

After a short period of time (2-3 days), however, high fever occurs with neurological symptoms such as loss of consciousness, seizures or paralysis. Then the patient must be treated with intensive care. However, there is no causal therapy against the virus.

In most patients, however, the disease heals without serious consequential damage. However, there is always a risk of neurological damage. Therefore, if you live in a risk area or are on vacation, it is best to get vaccinated against the TBE virus.

Granulomatous meningoencephalitis is an inflammation of the brain and meninges. In the case of granulomatous inflammation, small nodular cell aggregations (granulomas) are formed. These cell accumulations consist mainly of cells of the immune system such as macrophages (scavenger cells) or specialized white blood cells (monocytes).In granulomatous meningoencephalitis, the brain stem is usually affected.

These granulomatous centres of inflammation can be found along the blood vessels. The symptomatology depends on the location of the disease in the brain. If the brainstem is affected, there are mainly failures of the cranial nerves.

Necrotizing mengingoencephalitis is an inflammation of the brain and meninges. In this form of inflammation, necroses form very quickly in the center of the focus of inflammation, i.e. the brain cells in the center of the focus of inflammation die off. By destroying the brain tissue, the disease can only heal with scarring.

This is called defect healing. The clinical symptoms depend on the localization and severity of the disease. A complete healing rarely occurs, often consequential damages remain.

Primary amoebic meningoencephalitis is a rare and usually fatal disease. It is caused by an infection with amoebae. Amoebae are unicellular organisms that do not have a solid body shape, but can continuously change their body shape by forming pseudopods.

They usually live in stagnant fresh water. By bathing in contaminated water, the amoebae can enter the central nervous system through the mucous membranes and cause an infection there. The inflammation usually spreads quickly and can lead to death within 10 days.

Cryptococcal meningoencephalitis is an infection with an encapsulated fungus, Cryptococcus neoformans. It usually occurs in patients with an immune deficiency, e.g. in the context of AIDS. The fungus is usually absorbed through the respiratory tract by inhalation of contaminated dust.

Therefore the lungs are usually colonized first. If the immune system is weakened, the fungus can also spread to other organs, including the central nervous system. The inflammation of the brain and its membranes usually develops insidiously.

The disease can be treated with special fungal drugs such as Amphotericin B and Fluconazole. Listeria meningoencephalitis is an inflammation of the brain and meninges caused by Listeria. Listeria are gram-positive bacteria.

Most often, one gets infected through contaminated food (especially raw milk products). However, patients with a healthy immune system can usually fend off the bacteria. An infection rarely occurs.

The situation is different in immunocompromised patients, pregnant women or newborns. For these groups there is a higher risk of developing meningoencephalitis due to Listeria. An antibiotic therapy is possible. However, patients at risk should avoid foods potentially containing Listeria.