EncephalitisSyeda Ayesha Siddiqua

Roll #1051

Introduction Encephalitis is irritation, swelling, or acute

inflammation of the brain most often due to viral infection or when the body’s own immune system attacks brain tissue.

Rare condition that occurs most often in the first year of life and decreases with age.

Around 20,000 cases occur each year in the US

Figure 1 is computed tomography (CT) scan of a normal brain.Figure 2 is a CT scan that shows an accumulation of contrast material in infected areas and around the brain from encephalitis.

Causes of EncephalitisThe exact cause of encephalitis is often

unknown, but the most commonly diagnosed cause is a viral infection.

Primary encephalitis – occurs when a virus or other infectious agent directly infects the brain.

Secondary encephalitis –occurs when a virus first infects another part of your body and secondarily enters your brain.

Common Viral CausesVirus causes inflammation of the brain tissue,

brain tissue swells causing cerebral edema, which may destroy the nerve cells causing intracranial hemorrhage, thus, causing brain damage.

Exposure to viruses can occur through: Breathing in respiratory droplets from infected

personFrom contaminated food or drinksMosquito, tick, or other insect bites.Skin contact with the virus

Herpes Simplex Virus (HSV)HSV is the most common cause of encephalitis in

people of all ages, including infants.

There are two types of herpes simplex virus (HSV). Either type can cause encephalitis:

HSV type 1 (HSV-1) is usually responsible for cold sores or fever blisters around your mouth.

HSV type 2 (HSV-2) commonly causes genital herpes.

Encephalitis caused by HSV-1 is rare, but it has the potential to cause significant brain damage or death.

Other herpes virusesOther herpes viruses that may cause

encephalitis:

Epstein-Barr virus, which commonly causes infectious mononucleosis.

Varicella-zoster virus, which commonly causes chickenpox and shingles.

EnterovirusesInclude the poliovirus and the coxsackievirus,

which usually cause an illness with flu-like symptoms, eye inflammation and abdominal pain.

Mosquito-borne virusesArboviruses, or arthropod-borne viruses, are transmitted

by mosquitoes or other blood-sucking insects.

They can cause infections that include West Nile, La Crosse, St. Louis, western equine and eastern equine encephalitis.

Mosquitoes transfer the virus from a nonhuman host — such as a bird, chipmunk or horse — to humans.

Symptoms of an infection may appear within a few days to a couple of weeks after exposure to an arbovirus.

Tick-borne virusesThe Powassan virus is a well-known tick-

transmitted virus that causes encephalitis in the U.S. and Canada.

Symptoms usually appear about a week after exposure to the virus.

Rabies virusInfection with the rabies virus is transmitted

by a bite from an infected animal.

Causes a rapid progression to encephalitis once symptoms begin.

Rabies is a rare cause of encephalitis in the U.S.

Childhood InfectionsCommon childhood infections — such as

measles (rubeola), mumps, and rubella (German measles) — used to be fairly common causes of secondary encephalitis.

These causes are now rare because of the availability of vaccinations for these diseases.

Other Causes of EncephalitisAllergic reaction to vaccination Autoimmune disease – attack of the brain by the body’s

immune system.Acute Disseminated Encephalitis (ADEM)NMDA-Receptor Antibody EncephalitisVoltage Gated Potassium Channel-Complex Antibody

Associated LimbicHashimotos Encephalitis Rasmussen Encephalitis

Bacteria – Borrelia burgdorferi (Lyme disease), treponema pallidum (syphillis), and mycobacterium tuberculosis

Parasites - roundworms, taenia solium (cysticercosis), and toxoplasmosis in AIDs patients

Cancer and its effects on the body can cause encephalitis

Risk FactorsAnyone can develop encephalitis, however, there are factors that

may increase the risk of the condition.

Age – young children and older adults are at a greater risk for viral encephalitis. Whereas, encephalitis from the herpes simplex virus tends to be more common in people 20 to 40 years of age.

Weakened immune system - People who have HIV/AIDS, take immune-suppressing drugs, or have another condition causing a compromised or weakened immune system are at increased risk of encephalitis.

Geographic regions - Mosquito-borne or tick-borne viruses are common in particular geographic regions.

Signs & Symptoms

Some patients may have symptoms of a cold or stomach infection before the encephalitis symptoms begin.

Most people with encephalitis have mild flu-like symptoms such as: headache, fever, aches in muscles or joints, fatigue or weakness.

Emergency presentation of encephalitis:Confusion, agitation, or hallucinationsPoor responsivenessStuporComaMuscle weakness or paralysisSeizures Severe headachesDouble visionProblems with speech & hearingSudden change in mental function like, flat mood,

change in mood, or mood that is inappropriate for the situation.

Signs & symptoms in infants & young children:Bulging in soft spots (fontanels) of skullNausea and vomitingBody stiffness Inconsolable cryingPoor feeding or not waking for a feedingIrritability

ComplicationsComplications that may occur for months or be

permanent include:Persistent fatigueWeakness or lack of muscle coordinationPersonality changesMemory problems - especially among those who had

herpes simplex virus encephalitis.ParalysisHearing or vision defectsSpeech impairments - aphasiaEpilepsy

The most severe cases can result in coma or death.

Tests & DiagnosesBrain imaging - May reveal swelling of the brain.

Magnetic resonance imaging (MRI)Computerized tomography (CT)

Spinal tap (lumbar puncture) - cerebrospinal fluid (CSF) is extracted through spinal tap. Changes in this fluid can indicate infection and inflammation in the brain. The CSF is analyzed for elevated white blood cell counts, blood, and the presence of virus.

Other lab tests - Samples of blood or urine, or of excretions from the back of the throat can be tested for viruses or other infectious agents.

Electroencephalogram (EEG) - EEG can record the electrical activity of the brain. Abnormal patterns may be consistent with a diagnosis of encephalitis.

Brain biopsy - a procedure to remove a small sample of brain tissue (brain biopsy) is used if symptoms are worsening and treatments are having no effect.

TreatmentMild cases:

Bed restPlenty of fluidsAnti-inflammatory drugs— such as acetaminophen ibuprofen, and

naproxen sodium — to relieve headaches and fever.

Severe encephalitis:Breathing assistance and careful monitoring of breathing and

heart functionIntravenous fluids to ensure proper hydration and appropriate

levels of essential mineralsAnti-inflammatory drugs, such as corticosteroids, to help

reduce swelling and pressure within the skullAnticonvulsant medications, such as phenytoin (Dilantin), to

stop or prevent seizures.

Treatment (cont’d)Antiviral drugs:

Acyclovir (Zovirax)Ganciclovir (Cytovene)Foscarnet (Foscavir).

Follow-up therapy:Physical therapy to improve strength, flexibility, balance, motor

coordination and mobilityOccupational therapy to develop everyday skills and to use

adaptive products that help with everyday activitiesSpeech therapy to relearn muscle control and coordination to

produce speechPsychotherapy to learn coping strategies and new behavioral

skills to improve mood disorders or address personality changes — with medication management if necessary

PreventionVaccines - keeping up-to-date with vaccines is the most

effective way of reducing the risk of developing encephalitis. These include vaccines for measles, mumps, rubella, and if the virus exists in those areas, Japanese encephalitis and tick-borne encephalitis.

Protection from Mosquitoes- In areas known to have mosquitoes that carry encephalitis causing viruses, take measures to reduce the risk of being bitten. Wear appropriate clothing Avoid mosquito-infested areas Avoid going outside at specific times during the day when there

are lots of mosquitoes about Keep homes mosquito free and make sure there is no stagnant

water about your house. Use mosquito repellant

Case StudyA 65-year-old man of eastern European background was

transferred to a hospital with decreased conscious state and behavioral changes. His past history included depression (without prior psychotic episodes), alcohol abuse, and hypertension. He had no family history of psychiatric illness. His only regular medications were Citalopram and Olmesartan. At this facility, the patient became increasingly aggressive, requiring sedation and restraint. Following the oral administration of olanzapine and clonazepam, the patient became drowsy and was transferred to another hospital for a second opinion. Biochemistry and chest x-ray were normal, and computed tomography (CT) scan of the brain with contrast showed multiple old small basal ganglia infarcts. Delusions of misidentification of staff were present, as were visual hallucinations.

Case Study (cont’d)A lumbar puncture was performed which demonstrated

a protein of 0.4 g/L (RR, <0.45 g/L), glucose of 3.9 mmol/L (RR, 2.2–5.5 mmol/L), erythrocytes of 11, no leukocytes, and a negative gram stain. C Reactive Protein (CRP) rose from normal to 54 mg/L (RR, <20 mg/L). The patient was treated with IV acyclovir. HSV-1 PCR performed was positive. After commencing treatment, the patient showed significant improvement in behavior and cognition. CRP also dropped from a peak of 54 mg/L to normal. In total, he received twelve days of IV acyclovir and two days of oral acyclovir and was transferred back to prison on completion of treatment.

Fighting Encephalitis

Referenceshttp://www.mayoclinic.org/diseases-condition

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41710/http://www.webmd.com/a-to-z-guides/underst

anding-encephalitis-basicshttp://www.encephalitis.info/information/type

s-of-encephalitis/types-of-autoimmune-encephalitis/