Difference Between Meningitis And Encephalitis

There are two major infections at the level of the central nervous system, which are meningitis and encephalitis. They are different in their process of injury to the brain, and also in the treatment that must be instituted.

However, especially at the beginning, they may share similar symptoms. This leads us to have to perform different tests to discern and diagnose them.

Importance of differentiating meningitis and encephalitis

When we have an infection in the central nervous system (CNS), the first step among doctors is to orient themselves to what type of infection we are. This is key, as each requires different management and treatment.

In addition, these diseases have high mortality if the correct therapy is not applied. Therefore, nonspecific symptoms at onset are problematic.

The two diseases start with:

• Fever
• Headache
• Vomiting
• General discomfort

Meningitis

Meningitis infection is located in the layers that line the brain or brain, called the meninges. The main symptom that guides the diagnosis is a stiff neck. We also find the so-called meningeal signs :

• Kernig’s sign: When we lift a straight leg, the person with meningitis will reflexively bend the knee.
• Brudzinsky’s sign:  when we lift the person’s neck, they will flex their knees in a reflexive way.

Importantly, the patient tends to be oriented and conscious, unlike encephalitis. However, there may also be cases with disorientation.

When presenting a stiff neck and meningeal signs with altered consciousness, then we will have before us a picture of meningoencephalitis. Meningoencephalitis is an intermediate disease between meningitis and encephalitis, which combines symptoms of both.

Types of meningitis

There are two types of meningitis, depending on the causative agent:

• Bacterial: it is produced by bacteria, among which are pneumococcus and meningococcus most frequently. This meningitis has a poor prognosis if antibiotic treatment is not applied.
• Viral: they have a good prognosis. They tend to be self-limiting between 1 or 2 weeks and the clinical picture is very acute. In addition to presenting a stiff neck and meningeal signs, the person suffers from general symptoms, as if they had the flu. Treatment is symptomatic.

After performing a lumbar puncture for the differential diagnosis of meningitis, the fluid that comes out is the one that guides. In bacterial meningitis pus comes out, whereas in viral meningitis, the liquid is clear.

Encephalitis

Encephalitis is the inflammation of the brain or encephalon, therefore, the predominant symptoms are related to the impairment of brain function.

Just as meningitis had a stiff neck as its main symptom, encephalitis has its cardinal symptom in the alteration of consciousness. The patient is more asleep, confused and disoriented.

This alteration in consciousness can lead to coma. But earlier, changes in behavior and personality modifications, as well as seizures ,  can occur.

Herpes simplex virus

Encephalitis is a serious and fatal infection. It has a mortality of 50% if left untreated, and the main causative agent is usually a virus. 30% of viral encephalitis are caused by the herpes simplex virus, specifically type 1.

Therefore, when a person has symptoms that can be confusing between meningitis and encephalitis, what doctors tend to do, according to protocol, is to administer the treatment as if it were encephalitis. It is prioritized to stop a possible disease with higher mortality.

The treatment for herpes encephalitis is acyclovir, which is an antiviral that inhibits the synthesis of the virus’ DNA in infected cells, without altering healthy cells. If the person is over 50 years old, alcoholic, or has a chronic underlying disease, an antibiotic called ampicillin is added.

The differences between meningitis and encephalitis are not always clear

The symptoms of meningitis and encephalitis cannot always be precisely distinguished. Furthermore, in routine practice, it is difficult to get an accurate diagnosis right away. Studies, such as lumbar puncture, should be done to be sure.

In the presence of fever, headache, vomiting and general malaise, the consultation cannot wait. It will be the medical team that defines how to approach you and what timely treatment will stop the process that has begun.