Encephalitis vs. Meningitis

Encephalitis and meningitis are both infections of the brain, but they affect different parts of the brain. Meningitis is an infection in the membranes surrounding the brain and spinal cord, called the meninges, while encephalitis is inflammation of brain tissues.

Both conditions could be caused by viruses and bacteria, but encephalitis could also be triggered by an autoimmune response and meningitis could also be caused by injuries, cancer, lupus, and certain drugs.

Encephalitis and meningitis cause similar symptoms, but symptom onset varies between different types of encephalitis and meningitis. Both conditions may be treated with antibiotics and antiviral medications, but encephalitis may require a different set of treatments if it's caused by an autoimmune response.

Symptoms

Encephalitis and meningitis are both characterized by inflammation and swelling. They share some symptoms, but they also have some different symptoms.

Encephalitis Symptoms

Infectious encephalitis, which is encephalitis caused by a virus, often starts with flu-like symptoms or headache and evolves to altered mental status and problems with thinking, remembering, and reasoning.

On the other hand, autoimmune encephalitis, which is caused by an autoimmune response, typically progresses over the course of weeks. This type of encephalitis occurs when the immune system mistakenly attacks the brain.

Symptoms of encephalitis vary according to the area of the brain affected and, in autoimmune encephalitis, they can be different depending on the associated antibody, a protein produced by the immune system in response to a specific virus.

Physical symptoms of encephalitis can include:

• Fever
• Seizures
• Headache
• Movement disorders
• Sensitivity to light (photophobia)
• Sensitivity to sound
• Neck stiffness
• Loss of consciousness
• Weakness or partial paralysis in the arms and legs
• Double vision (diplopia)
• Impairment of speech or hearing
• Coma

Cognitive symptoms can include:

• Excessive sleepiness
• Confusion and disorientation
• Irritability
• Anxiety
• Psychosis
• Hallucinations
• Memory loss
• Other behavioral changes
• Cognitive impairment

Meningitis Symptoms

There are two types of meningitis: viral and bacterial meningitis. Viral meningitis is serious, but often less severe than bacterial meningitis.

In both types, symptoms can start suddenly, and include headache, fever, and a stiff neck. There are often other symptoms as well, including:

• Nausea
• Vomiting
• Photophobia
• Confusion
• Cold hands and feet
• Vomiting
• Fast breathing
• Muscle and joint pain
• Pale, mottled, or blotchy skin
• Spots or a rash
• Being very sleepy or difficult to wake
• Seizures

An infant with encephalitis or meningitis may have the following symptoms:

• Fever
• Lethargy
• Not waking for feedings
• Vomiting
• Stiffness in body
• Irritability
• Full or bulging soft spot on the head

Symptoms of bacterial meningitis can appear quickly or over several days. Typically they develop within three to seven days after exposure.

Causes

Viral meningitis is the most common cause of meningitis, and infectious encephalitis is the most common type of encephalitis.

Meningitis can be caused by other things as well, including bacteria, fungi, parasites, and medications, while encephalitis could also be a result of an autoimmune response.

Encephalitis Causes

Vaccines for measles, mumps, rubella, and chickenpox have reduced the rate of encephalitis from these diseases, but other viruses can cause encephalitis. The most common causes of infectious encephalitis are the herpes simplex viruses, varicella zoster virus, or enteroviruses, which also cause gastrointestinal diseases.

Encephalitis can also result from certain viruses carried by mosquitoes, ticks, and other insects or animals such as:

• West Nile virus
• Japanese encephalitis virus
• La Crosse virus
• St. Louis virus
• Equine viruses
• Powassan virus
• Zika
• Chikungunya

Bacteria, fungi, and parasites can rarely cause encephalitis.

Encephalitis can also be autoimmune. While the causes of autoimmune encephalitis are not well understood, it can sometimes result from a tumor. Some cases may be triggered by an infection.

Meningitis Causes

Meningitis can be caused by bacteria, viruses, fungi, and parasites. Viral meningitis is the most common type of meningitis, with nonpolio enteroviruses being the main cause.

Other viruses that can cause meningitis include:

• Mumps virus
• Herpes viruses, including Epstein-Barr virus, herpes simplex viruses, and varicella-zoster virus
• Measles virus
• Influenza virus
• West Nile virus
• Lymphocytic choriomeningitis virus

Meningitis can also be caused by bacteria. Several types of bacteria can cause meningitis. Leading causes in the United States include:

• Streptococcus pneumoniae
• Group B Streptococcus
• Neisseria meningitidis
• Haemophilus influenzae
• Listeria monocytogenes

Fungus- and parasite-related cases of meningitis are much less common. Parasites can cause rare forms of meningitis called eosinophilic meningitis.

Diagnosis

Encephalitis and meningitis require similar diagnostic tests. Testing will likely include:

• Neurological exam
• Blood or urine tests to check for signs of an infection
• Imaging tests including CT scan or MRI scan to look at abnormalities in the brain
• Lumbar puncture (spinal tap) to test the cerebrospinal fluid

If your doctor suspects that you have encephalitis, they will also order an electroencephalogram, which monitors the electrical activity in the brain.

Treatment

Both encephalitis and meningitis require immediate attention and treatment.

Encephalitis Treatment

Encephalitis can be treated with:

• Antiviral medications to fight viral infections affecting the brain
• Antibiotics to address underlying bacterial infections causing encephalitis
• Immunotherapy, such as steroids, intravenous antibodies, or plasma exchange, to address certain types of autoimmune encephalitis
• Medications or other therapies to control seizures
• A breathing tube, urinary catheter, or feeding tube may be necessary if the person’s encephalitis has caused loss of consciousness

Meningitis Treatment

Bacterial meningitis and viral meningitis are treated differently. While all bacterial meningitis is treated in hospital, only some viral meningitis requires a hospital stay.

There is no specific treatment for viral meningitis. Antiviral medicine may help people with meningitis caused by viruses such as the herpes viruses and influenza viruses. Mild meningitis generally resolves on its own within seven to 10 days.

Bacterial meningitis needs to be treated with antibiotics as soon as possible.

Prognosis

Due to the many variables related to these two conditions, the prognosis varies. It is critical to seek medical help as soon as signs are recognized and symptoms set in, as early treatment is best.

In most cases, people with mild encephalitis or meningitis can make a full recovery. For those who have severe cases, permanent impairment or death is possible. Even mild cases can take weeks or months to recover fully.

Summary

Encephalitis and meningitis can both cause inflammation and swelling in the brain. Bacterial meningitis and encephalitis require immediate medical attention as soon as symptoms appear, while viral meningitis usually resolves on its own within seven to 10 days.