Encephalitis of the Brain: Short and Long-Term Effects

A Rare and Serious Brain Condition

Encephalitis is a rare condition characterized by brain inflammation. Causes of encephalitis include infections, medication toxicity, or immune disorders.

Inflammation and swelling throughout the brain can cause confusion, headaches, and fatigue. Sometimes symptoms associated with inflammation are experienced in certain regions of the brain. Symptoms include vision changes, weakness of one side of the body, or seizures.

The symptoms of encephalitis can often be treated if the condition is detected right away. However, encephalitis can rapidly worsen, and serious long-term complications can result—including lifetime learning difficulties. This article describes the causes, effects, treatment, prognosis, and recovery of encephalitis.

<p>Illustration by Mira Norian for Verywell Health</p>

Illustration by Mira Norian for Verywell Health

Encephalitis vs. Meningitis: Differences and Similarities

Encephalitis is similar to meningitis, but there are some major differences. Encephalitis is an infection or inflammation of the brain tissue. Meningitis is infection or inflammation of the meninges, which are the three layers of tissue that protect the brain.

Differences between encephalitis and meningitis include:

  • Encephalitis is considered more severe than meningitis.

  • Encephalitis is more likely to be life-threatening than meningitis.

  • Meningitis is more common than encephalitis.

  • Meningitis is usually caused by contagious viral or bacterial infections.

  • Encephalitis is usually caused by an unusual reaction to a virus, bacterium, or fungus that is not usually otherwise harmful.

  • While it’s not a common outcome of meningitis, untreated meningitis can worsen and cause encephalitis, but encephalitis cannot develop into meningitis.

Learn More: Encephalitis vs. Meningitis

Role of Inflammation

Inflammation is a key component of meningitis and encephalitis. All causes of meningitis or encephalitis produce inflammation. Sometimes, the inflammation is secondary to an infection or medication, and sometimes, the inflammation is the primary cause of meningitis or encephalitis.

Immunosuppression can cause infectious encephalitis, and some medications, including some chemotherapy medications, can cause inflammatory encephalitis.

Causes and Risk Factors

Encephalitis has many different causes. Anyone can develop encephalitis, but having a weak immune system due to human immunodeficiency virus (HIV) or AIDS, advanced cancer, or powerful immune-suppressing therapies can increase the risk.

Causes of encephalitis include:

  • Herpes simplex encephalitis (HSE) is responsible for about 10% of all encephalitis cases.

  • Mosquito transmission can cause several types of encephalitis, including LaCrosse encephalitis, St. Louis encephalitis, and West Nile encephalitis.

  • Central nervous system inflammatory diseases, including multiple sclerosis and acute disseminated encephalomyelitis, can cause encephalitis.

  • Progressive multifocal leukoencephalopathy is a type of encephalitis that develops due to the reactivation of the John Cunningham (JC) virus, a common viral infection. Certain medications can trigger it.

  • Bacterial, fungal, and parasitic infections can cause encephalitis.

  • Autoimmune disorders, such as rheumatoid arthritis and lupus, can cause inflammatory encephalitis.

  • Leptomeningeal encephalitis is the spread of cancer throughout the brain and spinal cord.

  • Radiation treatment to the brain or chemotherapy can cause an inflammatory reaction.

  • Some cancers can cause paraneoplastic syndrome, which displays neurological symptoms caused by cancer-induced antibodies or hormones that target certain cells in the brain.

  • Rasmussen encephalitis is a congenital (present at birth) inflammatory disease of the brain.

According to the National Institute of Health (NIH), no cause is identified in up to 60% of encephalitis cases. Outside the United States, Japanese encephalitis is one of the most common causes of encephalitis worldwide.


Any injury, damage, or infection to the brain causes brain swelling that is described as edema. Inflammation often leads to leakiness of the small blood vessels, which allows fluid to collect in the damaged area.

Edema can include inflammatory cells, fluid, and blood. Edema in the brain causes pressure inside the skull, with symptoms of head pain, neurological symptoms, loss of consciousness, and even death. Treatment of edema is a key component of managing encephalitis.

Symptoms: How Does Encephalitis Start?

Encephalitis can cause a variety of nonspecific symptoms. It may develop and progress gradually if a chronic, inflammatory disease causes it, but it may progress very rapidly when it occurs due to an infection.

Neurological symptoms of encephalitis can include head pain, trouble concentrating, difficulty speaking, dizziness, trouble walking, difficulty concentrating, weakness in one or both sides of the body, impaired coordination, seizures, or loss of consciousness.

In addition to the neurological effects of encephalitis, edema can cause severe dysregulation of breathing, heart function, blood pressure, and kidney function due to disruption of the regions of the brain that regulate control of these functions.

In Children

Young children might not be able to express how they feel and can have more subtle symptoms of encephalitis. This may include excessive sleepiness, not paying attention to sounds and people around them, trouble concentrating, irritability, and lack of appetite.

In Older Adults

Older adults might have subtle symptoms of encephalitis, especially if they are already living with a condition that can make it difficult to communicate, such as dementia.

People who have other health conditions may experience symptoms such as sleepiness, difficulty with walking and balance, unusual behavior, and confusion.

Is Encephalitis Curable?

Encephalitis can be treated or cured in some circumstances. Treatment includes medication that will reduce inflammation and swelling, as well as treatment to manage the underlying cause.

Sometimes, even after receiving effective treatment of the inflammatory phase of encephalitis, people may experience long-term consequences, such as seizures or vision loss.


It is difficult to determine survival and prognosis of encephalitis. The incidence of autoimmune encephalitis in developed countries is approximately 5 to 10 per 100,000 people per year.

The case fatality rate can be as high as 30%, and permanent neurological or psychiatric complications can affect up to 50% of people. A 2023 study found that only 61% of people were able to return to their previous work or school life.

Encephalitis Treatment and Hospitalization

Encephalitis is usually treated in a hospital setting and often includes managing short-term complications, such as blood pressure changes or heart effects.

Treatments may include:

  • Blood pressure management

  • Treatment of edema with medications that reduce excess fluid in the body

  • Respiratory support, which may include oxygen supplementation or intubation

  • Anti-inflammatory medication, such as corticosteroids

  • Medication to treat infections, such as antiviral medication, antibacterial medication, antifungal medication or antiparasitic medication

  • Anti-seizure medication

Some challenges of managing encephalitis include treating conflicting symptoms—for example, some people may have low blood pressure but excess fluid in the brain, and the treatment for each condition could worsen the other.

Additionally, corticosteroids can reduce inflammation but may allow infections to thrive by decreasing the action of the immune system. Managing encephalitis during the inflammatory phase requires close monitoring, with potential adjustments in treatment.

Healing and Rehabilitation

After the acute inflammatory phase of encephalitis, people who survive usually undergo a long rehabilitation period. During this recovery and healing phase, healthcare providers will evaluate your abilities and begin planning your rehabilitation program.

Types of rehabilitation from encephalitis include:

  • Speech therapy: Your speech and understanding of other people's speech may be impaired after an episode of encephalitis. Working with a speech therapist can help you regain some of your language skills.

  • Cognitive therapy: People may experience slowed thinking, confusion, difficulty with memory and decision-making, and other cognitive (thinking) problems after encephalitis. You can work with a specialized therapist who will assess your thinking skills and help you with cognitive exercises to help rebuild as many of these skills as possible.

  • Physical therapy: Physical therapy involves supervised and at-home exercises that can help you regain strength, balance, and coordination.

  • Occupational therapy: You may need help learning to manage self-care, grooming, and getting around safely as you recover from encephalitis. Occupational therapy can help identify the everyday skills you need to work on and provide guidance to help you regain these skills.

  • Swallow evaluation and therapy: Encephalitis can affect your ability to chew and swallow. This can affect your nutrition, and it can also lead to choking hazards. A swallow evaluation can help identify which therapeutic approaches would benefit you.

  • Counseling: It could be helpful to speak with a counselor about how encephalitis has affected your life and emotional well-being. It can be extremely challenging to cope with limitations after recovering from encephalitis. Additionally, sometimes persistent pain can add to distress during the recovery phase. A counselor can help you and your family work through these feelings.

Encephalitis Long-Term Effects

Long-term effects of encephalitis may include a decline in physical or cognitive abilities, vision changes, epilepsy, or hydrocephalus (excess fluid in the brain). After recovery from the acute phase of encephalitis, you would be monitored for these long-term effects.

Complications of encephalitis:

  • Learning challenges: Children may encounter difficulties with learning and behavior after experiencing encephalitis at a young age.

  • Cognitive decline: Thinking difficulties and memory changes can develop due to encephalitis. Your healthcare team can't determine whether these changes are permanent until several months after you recover from encephalitis. You may need some testing to identify which cognitive problems you have, and you may be able to benefit from cognitive therapy.

  • Weakness or coordination difficulties: People can develop weakness on one side of the body or coordination problems affecting both sides of the body. You may have trouble walking or a diminished ability to use your body however you want. You may benefit from physical therapy to help you gain strength and coordination after you've recovered from encephalitis.

  • Vision changes: Loss of vision or decreased vision may be treatable with corrective lenses.

  • Epilepsy: If you have recurrent seizures after encephalitis, you will need to take antiepileptic medication to help reduce the frequency and severity of seizures.

  • Hydrocephalus: Excess fluid can build up in the brain due to blockage from inflammation. This may require a surgical procedure to remove the fluid or the placement of a ventricular shunt in the brain to prevent the fluid from building up repeatedly.

Follow-Up and Minimizing Risks

You will likely need to follow up with a neurologist and possibly a neurosurgeon after recovering from encephalitis. Follow-up evaluations will involve a discussion of your symptoms, a detailed neurological examination with an examination of your vision, blood tests to measure antiepileptic medication levels, and possibly neuroimaging.

If you developed encephalitis due to specific risk factors, such as a weak immune system, your healthcare providers will work with you to improve your immune system. This could include treatment for HIV or adjusting immune modifying medications.

If you are at risk of infections transmitted by ticks or mosquitos, you might need to use protective repellents or wear protective clothes during these exposures. Your treatment will be tailored to your health condition.


Encephalitis is inflammation of the brain tissue. It is a rare, dangerous, and potentially life-threatening condition. Encephalitis causes include a variety of infections, medications, and immune disorders. Some people are more susceptible to encephalitis because of a weak immune system, but anyone can get encephalitis.

Treatments can include medication to reduce inflammation and treatments to manage the symptoms. While encephalitis can be fatal, it can sometimes be curable.

Some people who survive may experience long-term consequences, such as seizures or physical or cognitive disabilities. Rehabilitation can help you regain many skills after recovering from encephalitis.

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