ENCEPHALITIS – Causes and Risk Factors, Causes, Clinical Manifestations, Diagnostic Evaluations, Management
It is an inflammation of the brain may be caused by viral, bacterial infection or it may be part of an allergic response to systematic viral illness or vaccination. Encephalitis is a rare condition. It occurs more often in the first year of life and decreases with age. The very young and the elderly are more likely to have a severe case.
CAUSES AND RISK FACTORS
The cause of encephalitis is often unknown, but the most commonly diagnosed cause is a viral infection. Known causes of encephalitis may include: viruses, bacteria, fungi and parasites.
Common viral causes of encephalitis include: herpes simplex virus, Epstein-barr virus, varicella-zoster virus, enteroviruses (poliovirus and coxsackievirus), arboviruses, or arthropod-borne viruses, tick-borne viruses and rabies virus. Common childhood infections – such as measles (rubeola), mumps, and German measles (rubella) – used to be fairly common causes of secondary encephalitis.
Other causes of encephalitis may include:
- An allergic reaction to vaccinations
- Autoimmune disease
- Bacteria, such as Lyme disease, syphilis and tuberculosis
- Parasites such as roundworms, cysticercosis, and toxoplasmosis in AIDS patients and other people who have a weakened immune system
- The effects of cancer
TYPES OF ENCEPHALITIS
- Infectious Encephalitis: The inflammation occurs as a direct result of an infection which is often viral. Viral encephalitis may develop during or after infection with any of several viral illnesses including influenza, herpes simplex, measles, mumps, rubella, rabies, chickenpox, and arbovirus infection including West Nile virus.
- Post-infectious Encephalitis: The inflammation caused by the immune system reacts to a previous infection or vaccine; this can occur many days, weeks or sometimes months after the initial infection. This likely occurs when disease-fighting proteins enlisted to fight an infection mistakenly attack molecules in the brain. Secondary encephalitis often occurs two to three weeks after the initial infection. Rarely, secondary encephalitis occurs as a complication of vaccination against a viral infection.
- Autoimmune Encephalitis: The inflammation is caused by the immune system reacting to an non-infectious cause, such as a tumor or antibodies. Autoimmune encephalitis is occurs when the immune system mistakes substances inside the brain as a threat and starts attacking them.
- Japanese Encephalitis (JEV): Japanese encephalitis is a viral infection that is spread by mosquitoes. The condition occurs throughout South East Asia, the Far East and the Pacific islands. People who are involved in farming in these parts of the world are most at risk.
- Chronic Encephalitis: The inflammation develops slowly over many months; it can be the result of a condition such as HIV, though in some cases there is no obvious cause. There are two main types of chronic encephalitis.
A. Subacute Sclerosing Panencephalitis – The inflammation occurs as a complication of a measles infection
B. Progressive Multifocal Leukodystrophy (PML) – The inflammation is caused by a usually harmless virus known as the JC virus
CLINICAL MANIFESTATIONS
Encephalitis is inflammation of the brain which is often a life-threatening. It usually begins with flu-like symptoms such as:
- High temperature (fever) of 38 degree celcius (100.4 degree F) or above
- Severe headache
- Nausea and vomiting
- Joint pain
After this initial stage, more serious symptoms can begin to develop, which may include:
- Changes in mental state, such as confusion, drowsiness or disorientation
- Seizures (fits)
- Loss of sensation or paralysis in certain areas of the body
- Changes in personality and behavior
- Loss of consciousness
Other symptoms of encephalitis can include:
- Sensitivity to bright lights (photophobia)
- Inability to speak
- Inability to control physical movements – muscle weakness
- Stiff neck
- Hallucinations – seeing and hearing things that are not actually there
- Loss of sensation in certain parts of the body
- Partial or total vision loss
- Involuntary eye movements, such as moving the eyes from side to side
- Involuntary movements of the face, arms and legs
Some types of autoimmune encephalitis can cause changes to mental health, such as
- Anxiety
- Unusual behaviors
- Delusions – believing things that are obviously untrue
- Paranoia – a belief that people are ‘out to get you’ and are actively plotting against you
DIAGNOSTIC EVALUATIONS
- Brain MRI
- CT scan of the head
- Brain biopsy
- Culture of cerebrospinal fluid (CSF), blood or urine Electroencephalogram (EEG)
- Lumbar puncture and CSF examination
- Tests that detect antibodies to a virus (serology tests)
- Test that detects tiny amounts of virus DNA (polymerase chain reaction – PCR)
MANAGEMENT
The goals of treatment are to provide supportive care (rest, nutrition, fluids) to help the body fight the infection, and to relieve symptoms. Reorientation and emotional support for confused or delirious people may be helpful.
A. Anti-inflammatory drugs – such as acetaminophen (Tylenol, others), ibuprofen (Advil, Motrin, others) and naproxen (Aleve, others) – are administer to relieve headaches and fever
B. Antiviral medications – such as acyclovir (Zovirax) and foscarnet (Foscavir) – to treat herpes encephalitis or other severe viral infections (however, no specific antiviral drugs are available to fight encephalitis)
Autoimmune encephalitis can be treated with corticosteroids, immunoglobulin therapy and plasmapharesis. An additional medication known as an immunosuppressant may also be recommended. Ciclosporin is a widely used immunosuppressant in the treatment of autoimmune encephalitis.
SUPPORTIVE CARE
Additional supportive care also is needed in the hospital for people with severe encephalitis. The care may include:
- Breathing assistance, as well as careful monitoring of breathing and heart function
- An oxygen mask will be used to help with breathing. Feeding tubes will provide nutrition and help to keep the body hydrated
- Intravenous fluids to ensure proper hydration and appropriate levels of essential minerals
- Anti-inflammatory drugs, such as corticosteroids, to help reduce swelling and pressure within the skull
- Anticonvulsant medications, such as phenytoin (Dilantin), to stop or prevent seizures
NURSING INTERVENTIONS FOR ENCEPHALITIS
- Monitoring pupils and vital signs frequently for increased intracranial pressure (ICP; irregular pupils, widening pulse pressure, tachycardia and irregular breathing hyperthermia)
- Monitor the patient’s response to medications and observe for adverse reactions
- Monitor neurologic status closely. Watch for subtle changes, such as behavior or personality changes, weakness or cranial nerve involvement
- To maintain a patient airway, many patients require endotracheal intubation, oxygen therapy, and mechanical ventilation if gas exchange is impaired
- Monitor fluid intake and output to ensure adequate hydration
- Maintain quiet environment and provide care gently, to avoid excessive stimulation and agitation, which may cause increase ICP
- Implement measures to limit the effect of immobility, such as skin care, range-of-motion exercises, and a turning and positioning schedule.
- Maintain seizure precautions; pad side rails of bed and have airway and suction equipment available at bedside
- Maintain standard precautions and additional isolation according to hospital policy to prevent transmission
- Administer antipyretics and other cooling measures as indicated. Provide fluid replacement through I.V. lines as needed
- Reorient patient frequently. Provide supportive care if coma develops; may last several weeks
- Encourage significant others to interact with patient with even while in coma and to participate in care to promote rehabilitation
ENCEPHALITIS – Causes and Risk Factors, Causes, Clinical Manifestations, Diagnostic Evaluations, Management