Encephalitis

Picture of encephalitis (inflammation of the brain)

• Encephalitis is inflammation of the brain.
• Bacteria or viruses, and rarely a fungus, or be noninfectious in origin can cause encephalitis.
• Symptoms of encephalitis include fever and headache, in addition to lethargy and confusion.
• Health care professionals make a diagnosis of encephalitis by performing a spinal tap to examine the cerebral spinal fluid. A CT scan or MRI of the brain may also be of use.
• The underlying cause of the encephalitis determines the treatment. If bacteria cause the encephalitis, then a doctor will prescribe antibiotics.
• Anyone experiencing encephalitis symptoms should seek medical treatment immediately.
• Close contacts can contract encephalitis also and will need medical evaluation.

• Encephalitis is a rare condition that is most often caused by viruses (viral encephalitis).
• It can also be caused by noninfectious diseases, such as systemic lupus erythematosus and Behçet's disease (an autoimmune disorder).
• The leading cause of severe encephalitis is the herpes simplex virus.
• Other causes include enterovirus infections or mosquito-borne viruses.
  • Eastern equine encephalitis (EEE),
  • Western equine encephalitis (WEE),
  • Venezuelan equine encephalitis (VEE),
  • Japanese encephalitis, and
  • Zika virus.
• The very young and the elderly are more likely to have more severe encephalitis.

Exposure to viruses can occur through breathing in respiratory droplets from infected people, certain insect bites, and direct skin contact.

Patients with suppressed immune systems (due to medications or diseases) have an increased risk for encephalitis.

Infectious forms of encephalitis are contagious. Viral and many bacterial forms of encephalitis are contagious. Several forms of bacterial encephalitis can be spread by respiratory and throat excretions. Encephalitis can also be caused by an infection in the body that spreads to the brain. Noninfectious encephalitis, such as from diseases systemic lupus erythematosus and Behçet's disease, are not contagious.

The signs and symptoms of encephalitis can range from very mild flu-like symptoms to potentially life-threatening events. Signs and symptoms of encephalitis include

• sudden fever,
• headache,
• vomiting,
• visual sensitivity to light,
• stiff neck and back,
• confusion,
• drowsiness,
• unsteady gait,
• irritability,
• loss of consciousness,
• poor responsiveness,
• seizures,
• muscle weakness,
• sudden severe dementia, and
• memory loss.

Anyone experiencing symptoms of encephalitis should see a doctor immediately.

People with encephalitis usually need treatment in the hospital. A family practice or general internal-medicine physician or an infectious-disease specialist will usually treat someone with encephalitis.

A health care professional diagnoses encephalitis after performing a thorough history and exam. The exam will incorporate special techniques to look for signs of inflammation of the membranes that surround the spinal cord and brain (meninges). The doctor will order specific tests to help determine the diagnosis.

Tests that evaluate individuals suspected of having encephalitis include cerebrospinal fluid analysis, brain scanning (such as CT scan or MRI scan), and an evaluation of the blood for infection and the presence of bacteria.

The most common method of obtaining a sample of cerebrospinal fluid (or CSF) for examination is a spinal tap. A spinal tap, or lumbar puncture (LP), involves the insertion of a needle into the fluid within the spinal canal. The needle goes between the spine's bony parts until it reaches the CSF. A medical professional then collects a small amount of fluid to send to the laboratory for exam. Evaluating the CSF is necessary for a definitive diagnosis of encephalitis and to decide on the best treatment options.

Abnormal spinal fluid results confirm the diagnosis and, in the event of an infection, by identifying the organism that caused the infection.

People require urgent treatment with antibiotic and/or antiviral medications if a physician suspects that person has encephalitis. Patients may need to take sedatives for irritability or restlessness. Doctors may administer other medications to decrease the fever or treat headaches.

The prognosis for encephalitis varies. Some cases are benign and patients recover fully. Other cases are severe. The type of infection present and how quickly treatment starts determine the prognosis. The acute phase of encephalitis may last for one to two weeks, with gradual or sudden resolution of fever and neurological symptoms. Neurological symptoms may require many months before full recovery occurs. Some patients will not fully recover.

Basic steps to avoid spread of infections (hand washing, covering mouth when coughing, etc.) can help prevent encephalitis.

Some vaccinations for bacterial or viral diseases can help prevent encephalitis.