Differences Between Meningitis and Encephalitis

Distinguishing between meningitis and encephalitis is no simple task for any medical team. These infections are similar in their beginnings but affect different structures.
Differences Between Meningitis and Encephalitis

Last update: 14 October, 2021

Meningitis and encephalitis are two major infections in the central nervous system. The way they affect the brain is different and so is the treatment.

They may share similar symptoms at the beginning, and so doctors will conduct various tests to discern and diagnose them properly.

The importance of differentiating between meningitis and encephalitis

The first step a physician will take in light of an infection in the central nervous system is to find out what type of infection it is. This is key as each one of them requires different management and treatment.

Moreover, these diseases have a high mortality rate without the right therapy. Thus, the nonspecific symptoms at onset are problematic.

The first symptoms of both diseases are:

  • Fever
  • Headache
  • Vomiting
  • General malaise

Meningitis

This infection happens in the layers that cover the brain — the meninges, and the main symptom is neck stiffness. There are meningeal signs as well:

  • Kernig’s sign. A person with meningitis will have the reflex of bending the knee when they lift an outstretched leg.
  • Brudzinsky’s sign. A person with meningitis will have the reflex of bending their knees when they lift their neck.

Note that an infected person tends to be oriented and conscious, unlike encephalitis. However, there may also be disorientation in some cases.

Furthermore, a person might have meningoencephalitis if there’s nuchal rigidity and meningeal signs with altered consciousness. Meningoencephalitis is an intermediate disease between meningitis and encephalitis, so it has the symptoms of both.

A man with a headache.
Meningitis causes severe headaches due to the pressure derived from inflamed meninges.

Types of meningitis

These depend on the causative agent:

  • Bacterial. Pneumococcus and meningococcus are the most common. Furthermore, this kind of meningitis has a poor prognosis without antibiotic treatment.
  • Viral. This one has a good prognosis. It tends to last between one to two weeks and the clinical condition is acute. In addition to presenting nuchal rigidity and meningeal signs, the person experiences general symptoms like those of the flu. The treatment depends on the symptoms.

The fluid that comes out of a lumbar puncture for the differential diagnosis of meningitis determines the diagnosis. There’s pus in bacterial meningitis but the liquid is clear in its viral form.

Encephalitis

This is the inflammation of the brain or encephalon; therefore, the predominant symptoms have to do with the affectation of the brain function.

Just as meningitis had a stiff neck as its main symptom, the main symptom of encephalitis is the alteration of consciousness. The patient often becomes groggy, confused, and disoriented.

This alteration of consciousness may lead to a coma. However, behavioral changes and personality changes may occur, as well as seizures beforehand.

A closeup of a virus.
The herpes simplex virus is the leading cause of encephalitis worldwide.

The leading cause of encephalitis worldwide

Encephalitis is a serious and deadly infection and has a 50% mortality rate if left untreated. Moreover, the main causative agent is usually the herpes simplex virus. In fact, thirty percent of viral encephalitis is caused by it, type 1 specifically.

As you can imagine, doctors tend to treat for encephalitis when a person has symptoms that indicate either meningitis or encephalitis — according to protocol. The priority is to stop a possible disease with higher mortality.

The treatment for herpes encephalitis is acyclovir, an antiviral that inhibits the synthesis of the virus DNA in infected cells, without altering healthy cells. The physician will also prescribe ampicillin, an antibiotic, if the person is over the age of 50, is an alcoholic, or has a chronic underlying disease.

The differences between meningitis and encephalitis aren’t always clear

One can’t always precisely differentiate the symptoms of meningitis and encephalitis. Moreover, it’s difficult to immediately make an accurate diagnosis in routine practice. Doctors must conduct studies, such as lumbar puncture, to be sure.

Consult a doctor as soon as possible if you have a fever, headache, vomiting, and general malaise. This is because only a medical team can determine the best approach and suggest timely treatment to stop the process.

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