an acute inflammation of the brain. The majority of cases are caused by either
a viral infection or the immune system mistakenly attacking brain tissue.
Although encephalitis is a rare disease, it can be life-threatening. Symptoms of encephalitis may be mild, with only mild fever and a general feeling of unwell, or they may be severe: seizures, altered consciousness, personality symptoms, behavior disturbances, memory loss, loss of coordination, paralysis, coma, etc.
In the United States, an estimated 19,000 people are hospitalized for meningitis. Around 15 percent of encephalitis cases occur in the HIV-infected population.
Types & Causes
There are two main types of encephalitis.
- Primary encephalitis. This condition occurs when a virus directly infects the brain and spinal cord.
- Secondary encephalitis. This condition results from a faulty immune system reaction to an infection elsewhere in the body.
The exact cause of encephalitis is often unknown. But the most common one, a viral infection has been widely known. Bacterial infections and noninfectious inflammatory conditions also can cause encephalitis.
The potential viruses that can cause encephalitis are categorized
into three groups: common viruses, childhood viruses, and arboviruses.
- Herpes simplex
- Epstein-Barr virus
These types of encephalitis are rare today, as vaccines can
prevent the childhood viruses that used to cause encephalitis. Some childhood
viruses that can cause encephalitis include:
- chicken pox (very rare)
The type of arbovirus that’s transmitted depends on the insect.
Below are different types of arboviruses:
- California encephalitis
- St. Louis encephalitis
- West Nile virus
- Colorado encephalitis
- Eastern equine encephalitis
- Kyasanur forest disease
causes of encephalitis may include:
- An allergic reaction to vaccinations
- Autoimmune disease
- Bacteria such as Lyme disease and tuberculosis
- Parasites such as roundworms, cysticercosis, and toxoplasmosis
- The effects of cancer
symptoms are usually flu-like symptoms:
- Aches in muscles or joints
- Fatigue or weakness
Less common symptoms:
The individual may also experience:
- Nuchal rigidity (neck stiffness)
- Stiffness of the limbs,
- Slow movements
- Drowsiness, lethargy, and possibly coma
- Photophobia (excessive sensitivity to light).
More serious cases:
Sometimes the signs and symptoms
are more severe, and might include:
- Confusion, agitation or hallucinations
- Loss of sensation or paralysis in certain areas of the face or body
- Weakness in one or more areas of the body
- Problems with speech or hearing
- Loss of consciousness
Symptoms in infants and young people:
In infants and young children,symptoms might also include:
- Bulging in the soft spots (fontanels) of
an infant’s skull
- Nausea and vomiting
- Body stiffness
- Incessant crying
- Poor feeding or not waking for a feeding
- Personality changes, irritability, or
typically made by a combination of clinical, laboratory, neuroimaging, and
Your doctor will start with a thorough
physical examination and medical history.
on different symptoms, doctors will employ different diagnostic methods：
It is used to when the patient feels confused and drowsy.
- A diagnosis of meningitis or
It is considered when the patient’s stiff neck is caused by
irritation of the meninges
Your doctor might also recommend:
- Brain imaging.
MRI or CT images can reveal any swelling
of the brain or another condition that might be causing your symptoms, such as
It might reveal higher-than-normal levels of protein and white
blood cells in the patient.
- Other lab tests
Samples of blood, urine or excretions
from the back of the throat can be tested for viruses or other infectious
- Electroencephalogram (EEG)
Electrodes affixed to your scalp record
the brain’s electrical activity.
- Brain biopsy
Brain biopsy is usually done only if symptoms are worsening and treatments are having no effect.
will depend largely on your age and condition, as well as the form and cause of
For patients with encephalitis caused by a
bacterial infection, antibiotics are usually prescribed.
Antiviral medications commonly used to treat encephalitis
For patients with herpes-related encephalitis,
supportive care and antiviral therapy with drugs are needed.
who are hospitalized with severe encephalitis might need:
- Breathing assistance, and careful monitoring of breathing and heart function
- Intravenous fluids
- Anti-inflammatory drugs
- Anticonvulsant medications
Other treatments may be used to lower fever, provide hydration, treat seizures if they develop, and reduce any pressure in the skull.