Encephalitis

Description:
Encephalitis is inflammation of the brain. There are several causes, but the most common is viral infection. Severity is variable. Encephalitis often causes only mild flu-like signs and symptoms — such as a fever or headache — or no symptoms at all.It may include headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.

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Encephalitis can also cause confused thinking, seizures, or problems with senses or movement.

Rarely, encephalitis can be life-threatening. Timely diagnosis and treatment are important because it’s difficult to predict how encephalitis will affect each individual.

Symptoms:
Most people with viral encephalitis have mild flu-like symptoms, such as:

  • Headache
  • Fever
  • Aches in muscles or joints
  • Fatigue or weakness
  • Sometimes the signs and symptoms are more severe, and might include:

Confusion, agitation or hallucinations:

  • Seizures
  • Loss of sensation or paralysis in certain areas of the face or body
  • Muscle weakness
  • Problems with speech or hearing
  • Loss of consciousness

In infants and young children, signs and symptoms might also include:

  • Bulging in the soft spots (fontanels) of an infant’s skull
  • Nausea and vomiting
  • Body stiffness
  • Poor feeding or not waking for a feeding
  • Irritability

Causes:
The exact cause of encephalitis is often unknown. But when a cause is known, the most common is a viral infection. Bacterial infections and noninfectious inflammatory conditions also can cause encephalitis.

There are two main types of encephalitis:

  1. Primary encephalitis. This condition occurs when a virus or other agent directly infects the brain. The infection may be concentrated in one area or widespread. A primary infection may be a reactivation of a virus that had been inactive after a previous illness.
  2. Secondary encephalitis. This condition results from a faulty immune system reaction to an infection elsewhere in the body. Instead of attacking only the cells causing the infection, the immune system also mistakenly attacks healthy cells in the brain. Also known as post-infection encephalitis, secondary encephalitis often occurs two to three weeks after the initial infectio.

Viral causes:

Viral encephalitis can occur either as a direct effect of an acute infection, or as one of the sequelae of a latent infection. The majority of viral cases of encephalitis have an unknown cause, however the most common identifiable cause of viral encephalitis is from herpes simplex infection. Other causes of acute viral encephalitis are rabies virus, poliovirus, and measles virus.

Additional possible viral causes are arbovirus (St. Louis encephalitis, West Nile encephalitis virus), bunyavirus (La Crosse strain), arenavirus (lymphocytic choriomeningitis virus), reovirus (Colorado tick virus), and henipaviruses. The Powassan virus is a rare cause of encephalitis.

Bacterial and other causes:
It can be caused by a bacterial infection, such as bacterial meningitis,[12] or may be a complication of a current infectious disease syphilis (secondary encephalitis).

Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Lyme disease or Bartonella henselae may also cause encephalitis.[citation needed]

Other bacterial pathogens, like Mycoplasma and those causing rickettsial disease, cause inflammation of the meninges and consequently encephalitis. A non-infectious cause includes acute disseminated encephalitis which is demyelinated.

Limbic encephalitis:
Limbic encephalitis refers to inflammatory disease confined to the limbic system of the brain. The clinical presentation often includes disorientation, disinhibition, memory loss, seizures, and behavioral anomalies. MRI imaging reveals T2 hyperintensity in the structures of the medial temporal lobes, and in some cases, other limbic structures. Some cases of limbic encephalitis are of autoimmune origin.

Autoimmune encephalitis:
Autoimmune encephalitis signs can include catatonia, psychosis, abnormal movements, and autonomic dysregulation. Antibody-mediated anti-N-methyl-D-aspartate-receptor encephalitis and Rasmussen encephalitis are examples of autoimmune encephalitis. Anti-NMDA receptor encephalitis is the most common autoimmune form, and is accompanied by ovarian teratoma in 58 percent of affected women 18–45 years of age.

Encephalitis lethargica:
Encephalitis lethargica is identified by high fever, headache, delayed physical response, and lethargy. Individuals can exhibit upper body weakness, muscular pains, and tremors, though the cause of encephalitis lethargica is not currently known. From 1917 to 1928, an epidemic of encephalitis lethargica occurred worldwide.

Diagnosis:
People should only be diagnosed with encephalitis if they have a decreased or altered level of consciousness, lethargy, or personality change for at least twenty-four hours without any other explainable cause. Diagnosing encephalitis is done via a variety of tests:

  • Brain imaging. MRI or CT images can reveal any swelling of the brain or another condition that might be causing your symptoms, such as a tumor.
  • Spinal tap (lumbar puncture). A needle inserted into your lower back removes cerebrospinal fluid (CSF), the protective fluid that surrounds the brain and
  • spinal column. Changes in this fluid can indicate infection and inflammation in the brain. Sometimes samples of CSF can be tested to identify the virus or other infectious agent.
  • Other lab tests. Samples of blood, urine or excretions from the back of the throat can be tested for viruses or other infectious agents.
    Electroencephalogram (EEG). Electrodes affixed to your scalp record the brain’s electrical activity. Certain abnormal patterns may indicate a diagnosis of encephalitis.
  • Brain biopsy. Rarely, a small sample of brain tissue might be removed for testing. Brain biopsy is usually done only if symptoms are worsening and treatments are having no effect.

Treatment:
Treatment (which is based on supportive care) is as follows:

  • Antiviral medications (if virus is cause)
  • Antibiotics, (if bacteria is cause)
  • Steroids are used to reduce brain swelling
  • Sedatives for restlessness
  • Acetaminophen for fever
  • Occupational and physical therapy (if brain is affected post-infection)
    Pyrimethamine-based maintenance therapy is often used to treat Toxoplasmic Encephalitis (TE), which is caused by Toxoplasma gondii and can be life-threatening for people with weak immune systems. The use of highly active antiretroviral therapy (HAART), in conjunction with the established pyrimethamine-based maintenance therapy, decreases the chance of relapse in patients with HIV and TE from approximately 18% to 11%. This is a significant difference as relapse may impact the severity and prognosis of disease and result in an increase in healthcare expenditure.

Prognosis:
Identification of poor prognostic factors include cerebral edema, status epilepticus, and thrombocytopenia. In contrast, a normal encephalogram at the early stages of diagnosis is associated with high rates of survival.

Prevention:
The best way to prevent viral encephalitis is to take precautions to avoid exposure to viruses that can cause the disease. Try to:

  • Practice good hygiene. Wash hands frequently and thoroughly with soap and water, particularly after using the toilet and before and after meals.
  • Don’t share utensils. Don’t share tableware and beverages.
  • Teach your children good habits. Make sure they practice good hygiene and avoid sharing utensils at home and school.
  • Get vaccinations. Keep your own and your children’s vaccinations current. Before traveling, talk to your doctor about recommended vaccinations for different destinations.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
https://en.wikipedia.org/wiki/Encephalitis
https://www.mayoclinic.org/diseases-conditions/encephalitis/symptoms-causes/syc-20356136

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