When we want to refer to the inflammation of the brain tissue we talk about encephalitis . As with any other organ, this infection can have multiple origins. However, it is the most lethal of infections.

What is encephalitis?

Inflammation of the central nervous system can have serious consequences that leave permanent sequelae. For this reason it is important to be very clear about the symptoms and what to do if you suspect encephalitis.

Without going into too many details and medical technicalities, we are going to see in a useful way how encephalitis manifests itself, what origins are most likely, and what treatment and prognosis can be expected from the patient who is suffering from it.


It is important to differentiate encephalitis from meningitis . The former consists of inflammation of the tissue of the brain or spinal cord. The second refers to inflammation of the meninges, the layers of tissue that separate the brain from the skull.

Encephalitis produces a clinical picture with symptoms that span a very wide range of severity. The most common mild symptoms include those explained below.

1. Fever

As with any infection, the body defends itself against viral agents through fever. The increase in temperature helps to kill the bacteria or virus that is causing the infection.

2. Headache

When we suffer an infection, the vessels usually dilate so that more blood reaches the infected area and we can better fight off external agents. What happens with this is that the area swells and compresses the tissue against the walls. This is why patients with encephalitis suffer from headaches.

3. Stiff neck

Muscle aches are very common in all kinds of infectious processes, and encephalitis is no exception. Besides pain, it is frequent to find that patients have very rigid neck and upper back muscles.

4. Fatigue

Because of the infection, it is common for the patient to feel exhausted. After all, the body needs all the energy it can get to fight the infection, and rest is beneficial for recovery.

Because these symptoms are very general and frequent in infections, it will not be until the development of more severe and specific symptoms that encephalitis will be suspected. As a principle, the more neurological symptoms reflect a greater severity of the infection and a greater urgency in its treatment. Neurological symptoms include:

  • High fever
  • Confusion
  • Dizziness
  • Hallucinations
  • Motor slowness
  • Irritability
  • Seizures
  • Coma

Naturally, in the presence of any of these manifestations the guideline for action is to go to the medical emergency room. Neurological symptoms indicate severe involvement of the nervous system and may be potentially disabling, if not lethal.

The diagnosis will be made through a lumbar puncture , which will allow the analysis of the contents of the cerebrospinal fluid to confirm the presence of signs of infection, through neuroimaging such as a magnetic resonance imaging (MRI) or a computerized axial tomography (CT). Other methods include electroencephalograms, blood tests, or even a brain biopsy, where a tiny sample of brain tissue is removed to examine its contents.

Common causes

Our body is built in a surprisingly intelligent way. Especially when it comes to the nervous system, there are more obstacles and safety measures than one might suspect. There is a reason why most infectious processes do not extend to the brain. In order to keep toxic substances in the blood from coming into contact with the cerebrospinal fluid in the brain and spinal cord, the body builds a barrier between the two.

However, when some harmful agents carried in the blood manage to penetrate the barrier a problem occurs : the body’s natural defences cannot get through either and the infection becomes difficult to treat. This is why many of the treatments are administered directly on the cerebrospinal fluid as they cannot pass the body’s own defences.

Common viral infections

Although encephalitis can be caused by both viruses and bacteria, most often a viral infection is found . The virus most frequently associated with encephalitis in developed countries is herpes. Although this virus normally only travels from the nerve to the skin, it sometimes reaches the brain, dangerously affecting the nervous system. Other common viruses include cytomegalovirus, Epstein-Barr, and human immunodeficiency virus (HIV).

There is a percentage of children who, because they do not get vaccinated when they should, suffer from encephalitis due to virus infection against which they should be protected. These viruses include chickenpox and rubella. For this reason, among others, it is essential to comply with the vaccine portfolio and protect the youngest from these types of infections.


In addition to common viruses, viruses transmitted through insect bites are another common cause of encephalitis. Mosquito bites and ticks are the most common means of transmitting these viruses , in the urban world and especially when travelling to tropical areas where insects proliferate. For this reason, as a preventive measure it is necessary to be vaccinated against these viruses.

Treatment and prognosis

Viruses that cause encephalitis are treated with antiviral drugs , normally from the entrance to the emergency room so as not to waste time. Once the diagnosis is confirmed, treatment will continue, unless infection by bacteria is found, in which case the patient will be switched to antibiotics. In addition, intravenous fluids, anticonvulsants, antipyretics and oxygen will be administered through a mask.

The prognosis depends on the extent of brain damage. The longer the infection has lasted and the more severe it is, the more damage there will be and the less function there will be over time. If the patient is not severely affected, problems with memory, executive functions, swallowing, mood disorders, concentration difficulties, and all kinds of neurological symptoms caused by the destruction of nerve cells may be found and remain until after the infection. Similar to patients with dementia, it is possible to recover some of the functions through cognitive rehabilitation and training.