Encephalitis is an acute inflammation of the brain that usually results from a viral infection or a dysfunction of the immune system that mistakenly attacks brain tissue. It usually starts with fever and a headache. She is rarely mortal.
Definition of encephalitis
Encephalitis, what is it?
Encephalitis is an inflammation of the brain. Viral infections are the most common cause of the disease.
Encephalitis can cause symptoms similar to those of the flu, such as fever or severe headache. It can also cause confused thoughts, seizures or motor problems. However, many cases of encephalitis cause only mild symptoms or appear without symptoms.
Serious cases of encephalitis, although relatively rare, can be fatal. Since the course of encephalitis is unpredictable, it is important to have timely diagnosis and treatment.
Causes of encephalitis
The exact cause of encephalitis is often unknown, but the most commonly diagnosed cause is a viral infection. Bacterial infections and noninfectious inflammatory diseases can also cause encephalitis.
An infection can lead to one of two conditions affecting the brain:
- Primary encephalitis occurs when a virus or other infectious agent directly affects the brain. The infection can be concentrated in one place of the body or diffuse. Primary infection may be reactivation of an inactive (latent) virus following an earlier disease.
- Secondary encephalitis is a defective reaction of the immune system in response to an infection. Instead of attacking only cells that cause an infection, the immune system also mistakenly attacks healthy cells in the brain.
Secondary encephalitis often occurs two to three weeks after the initial infection. It is rarely a complication of a vaccination.
Common viral causes
The common causes of encephalitis are:
- Herpes virus. There are two types of herpes simplex virus (HSV). Either type can cause encephalitis. HSV type 1 (HSV-1) is usually responsible for colds or cold sores around the mouth, and HSV type 2 (HSV-2) usually causes genital herpes. Encephalitis caused by HSV-1 is rare, but it can cause significant brain damage or death.
- Other herpes viruses can cause encephalitis such as the Epstein-Barr virus, which usually causes infectious mononucleosis, and the chickenpox-zoster virus, which usually causes chicken pox and shingles.
- Enterovirus. These viruses include poliovirus and coxsackievirus, which usually cause illness with flu-like symptoms, eye inflammation and abdominal pain.
- Viruses transmitted by mosquitoes. Arboviruses or viruses transmitted by arthropods are transmitted by mosquitoes or other insects that suck the blood. Mosquitoes transfer the virus from a non-human host – like a bird or a horse – to humans. The symptoms of an infection can appear from a few days to a few weeks after exposure to an arbovirus.
- Virus transmitted by ticks. Powassan virus is a known virus transmitted by ticks that caused encephalitis in the United States and Canada. Symptoms usually appear about a week after exposure to the virus.
- Rabies virus. Infection with the rabies virus, which is usually transmitted by a bite from an infected animal, causes a rapid progression of encephalitis once the symptoms begin. Rabies is a rare cause of encephalitis in the United States.
- Infectious infections. Common childhood infections – such as measles, mumps, and rubella – were fairly common causes of secondary encephalitis. These causes are now rare because of vaccinations against these diseases.
Diagnosis of encephalitis
Questions about symptoms, risk factors, and medical history are important for diagnosing encephalitis. Diagnostic tests that may be required include the following:
- Neurological examination. This examination will detect a confused and sleepy patient.
- Brain imaging. Brain imaging is often the first test if symptoms and history of patients suggest the possibility of encephalitis. Images may reveal brain swelling or other condition that can cause the same symptoms (eg a tumor). The technologies used are magnetic resonance imaging (MRI), which can be useful for detecting changes in brain structure, or even a computed tomography (CT) scan,
- Lumbar puncture. The doctor inserts a needle into the lower back to extract cerebrospinal fluid (CSF), the protective fluid that surrounds the brain and spine. Changes in this fluid may reflect infection and inflammation in the brain. In some cases, CSF samples may be tested to identify the virus or other infectious agent.
- Other laboratory tests. Blood or urine samples or excretions from the back of the throat may be tested for viruses or other infectious agents.
- Electroencephalogram (EEG). The doctor may request an EEG, a test in which a series of electrodes are placed on the scalp. The EEG records the electrical activity of the brain. Abnormal activity may be consistent with a diagnosis of encephalitis.
- Biopsy of the brain. This test, which consists of taking a small sample of brain tissue, is only used when symptoms worsen and treatments have no effect.
Evolution and possible complications
The complications resulting from encephalitis depend on several factors such as the age, the cause of the infection and the time when the treatment started.
Younger patients tend to recover without many problems, while older patients have an increased risk of complications and mortality.
In most cases, people with low-grade encephalitis will not have a long-term complication.
The most serious complications that can persist for months or that may be permanent are:
- Persistent fatigue.
- Weakness or lack of muscle coordination.
- Personality changes (eg mood swings, frustration, anger)
- Memory problems.
- Hearing or visual problems
- Speech disorders.
The person will answer some of the following questions or answer questions about their child:
- When did the symptoms begin?
- Have you recently started taking new medicines? If so, what is the drug?
- Have you been bitten by a mosquito or tick in recent weeks?
- Have you ever traveled? If so, where?
- Have you recently had a cold or flu?
- Have you been vaccinated? Are you up to date with your vaccinations?
- Have you been exposed recently to wild animals or known toxins?
- Have you had unprotected sex with a new sexual partner?
- Do you have an illness or are you taking medications that weaken your immune system?
Symptoms of encephalitis
Most people with viral encephalitis have the following symptoms:
- Muscle aches or joints.
- Fatigue and sleepiness.
- Sensitivity to light.
- Rigidity of the neck.
More serious cases require prompt medical attention. Encephalitis can get worse and cause other signs and symptoms such as:
- Confusion, agitation or hallucinations.
- Loss of sensation or paralysis in certain areas of the face or body.
- Muscular weakness.
- Double vision.
- Perception of bad smells.
- Language or hearing problems.
- Loss of consciousness and memory.
Signs and symptoms in infants and young children may also include:
- Fontanelles dug.
- Nausea and vomiting.
- Body rigidity.
- Continuous crying.
- Bad nutrition.
Immediate care is essential if a person has any of the symptoms associated with more severe cases of encephalitis. Severe headaches, fever and altered consciousness require emergency care.
Anyone can develop encephalitis. Factors that may increase the risk of the disease include:
- Age. Some types of encephalitis are more common or more severe in some age groups. In general, young children and the elderly are more exposed to most types of viral encephalitis. Encephalitis of the herpes virus tends to be more common in people aged 20 to 40 years.
- A weakened immune system. People with AIDS, those taking antidepressant medications, or other immune-compromising conditions are at increased risk for encephalitis.
- Location. Viruses transmitted by mosquitoes or ticks are common in some geographic areas.
- Season of the year. Mosquito and tick-borne diseases tend to be more prevalent in the spring, summer and early fall in many countries such as the United States.
The best way to prevent viral encephalitis is to take precautions to avoid exposure to viruses that can cause the disease:
- Have a good hygiene. Wash your hands frequently with soap and water, especially after using the toilet and before and after meals.
- Teach children good hygiene habits.
- Get vaccinated or update these vaccines, especially before traveling to a country at risk.
Protection against mosquitoes and ticks
To minimize exposure to mosquitoes and ticks, the following tips should be followed:
- Dress for protection, for example by wearing long-sleeved shirts and long pants between dusk and dawn when mosquitoes are most active.
- Apply an anti-mosquito containing a recognized active ingredient (eg DEET, eucalyptus or picaridine).
- Use an insecticide containing eg permethrin. These products, which repel and kill tics and mosquitoes, are sprayed on clothes and tents. Permethrin should not be applied to the skin.
- Avoid mosquitoes. Refrain from unnecessary activities in places where mosquitoes are most prevalent. If possible, avoid being outside twilight until dawn, when mosquitoes are the most active.
- Keep mosquitoes out of your home. Repair holes in windows and mosquito nets.
- Get rid of water sources outside your home. If possible, eliminate stagnant water in your garden, where mosquitoes can put their eggs.
- Look for external signs of viral disease. If you notice sick or dying birds or animals, report it to your local health unit.
Protection for young children
- Insecticides are not recommended for infants less than 2 months old. Instead, cover a baby carrier or stroller with a mosquito net.
- Always help children use a mosquito repellent.
- Spray clothing and exposed skin.
- Apply the insecticide outdoors to reduce the risk of inhalation of the product.
- Spray a repellent on your hands, then apply it on your child’s face. Take care of the eyes and ears.
- Do not use insecticide on the hands of young children as they can put their hand in their mouths.
Treatments of encephalitis
The treatment of mild cases includes:
- Bed rest.
- To drink a lot.
- Anti-inflammatories such as acetaminophen and ibuprofen to relieve headaches and fever.
- Antivirals. Cases of encephalitis due to certain viruses usually require intravenous antiviral treatments. Antiviral drugs commonly used to treat encephalitis include acyclovir and ganciclovir.
Some viruses, such as insect-transmitted viruses, do not respond to these treatments. However, since the specific virus may not be identified immediately or cannot be identified at all, treatment with acyclovir is often started immediately. This medicine can be effective against the herpes virus.
Side effects of antiviral drugs may include nausea, vomiting, diarrhea, and muscle or joint pain. Serious serious problems may include abnormal renal or hepatic function or suppression of bone marrow activity. Appropriate tests are used to monitor serious side effects.
Extra care at the hospital is also needed for people with severe encephalitis. This care may include:
- Respiratory assistance, as well as careful monitoring of breathing and heart functions.
- Intravenous fluids to ensure proper hydration and appropriate levels of essential minerals.
- Anti-inflammatories such as corticosteroids, to reduce the pressure in the skull, especially in cases of post-infectious encephalitis (secondary).
- Anticonvulsant medications such as phenytoin to stop or prevent seizures.
After the treatment of the disease, it may be necessary to receive additional therapy depending on the type and severity of complications. This therapy can include:
- Physiotherapy to improve strength, flexibility, balance, motor coordination and mobility.
- A therapy to develop daily skills.
- A reeducation of speech.
- Behavioral psychotherapy to reduce mood disorders or resolve personality changes, accompanied by medication if necessary.