Encephalitis is acute inflammation of the brain that is most common in children, the elderly, and those with weak immune systems. It can be caused by viruses, bacteria, or non-infectious conditions. Symptoms include fever, headache, confusion, seizures, and neurological deficits. Diagnosis involves imaging tests, cerebrospinal fluid analysis, and blood tests to identify the causative agent. Treatment focuses on relieving symptoms, reducing swelling and seizures with medications, and treating any identified infections. Outcomes vary depending on the severity and specific cause of the inflammation.

1. ENCEPHALITIS

2. WHAT IS ENCEPHALITIS?
Acute inflammation of the brain.
Children, elderly and those with a weak
immune system are those who are more prone
to encephalitis.
The treatment given and the chances to
recovery depend completely on the virus
involved and how severe the inflammation is.
Acute – encephalitis : affects brain directly

3. CAUSES
The exact cause of encephalitis is unknown.
Usually caused by a virus or sometimes even a bacterial
infestation as well as non infectious inflammatory
conditions may cause encephalitis .
Few viruses that may be instrumental in causing
encephalitis includes –
1)Herpes simplex
2) Polio viruses
3)Mosquito – borne viruses
4)Tick – borne
5) Rabies
6) childhood viruses

4. RATE OF INCIDENCE
There were no studies that specifically addressed the
incidence of encephalitis. However, there were
studies from various countries that mentioned the
incidence of encephalitis in different settings. Those
studies suggested of 1.77 to 6.34 for tropical
countries and an IR of 0.51-7.4 for Western
industrialized countries.
An IR of 145-185 was recorded during an epidemic in
Nepal in 1997. A hospital-based study from Andhra
Pradesh, India, suggested an IR of 1. A review article
suggested that the minimum IR must be fixed at 6.0
based on earlier studies

5. Biological Base
• Just as a thief with a copied key can open a lock that is not his,
a virus begins to enter a cell via a similar type of crime.
• Outermost layer of virus has special protiens that latch onto a
cell and “pick” the molecular locks on its surface.
• These locks, which cover the surface of a cell, are called
receptors.

6. • When there is no virus, receptors are used to
convey important signals from the outside
world to the inside of the cell.
• Unrelated viruses can attach (bind) at different
times to the same kind of receptor on a cell
surface.
• A virus’s preference for infecting a certain type
of cell (like a neuron) is called tropism, and is
caused by the specific interaction of the virus
with a receptor found on that kind of cell.

7. • In addition to binding to a cell surface receptor,
a virus often has to bind to a second cell
surface receptor, called co-receptor. In these
cases, its only after this second interaction that
a virus can enter into a cell.

8. TYPES OF ENCEPHALITIS

9. • Infectious encephalitis
• Autoimmune encephalitis
• Chronic encephalitis
• Limbic encephalitis
• HIV encephalitis
• Encephalitis Lethargica

10. Infectious Encephalitis
• Viruses are the most common agents that cause
Infectious Encephalitis. Within the British Isles
herpes simplex virus (the cold sore virus) is
the virus most frequently identified.
• Some of the known types of Infectious
Encephalitis are:
o Herpes Simplex Encephalitis
o West Nile Encephalitis
o Tick Borne Encephalitis
o Japanese Encephalitis

11. Autoimmune Encephalitis
• Autoimmune Encephalitis may be triggered by
infection in which case the term "Post-infectious
Encephalitis" is used. ADEM( Acute Disseminated
Encephalomyelitis ) is a Post-infectious Encephalitis.
The illness usually follows in the wake of a mild viral
infection (such as those that cause rashes in childhood)
or immunisations. Typically there is a delay of days to
two to three weeks between the triggering infection and
development of the Encephalitis.
• It has recently been recognised that there are other
types of Autoimmune Encephalitis resulting from an
attack of the brain by the body's immune system.

12. Limbic Encephalitis
• The term ‘Limbic Encephalitis’ (LE) is used
when the limbic areas of the brain are inflamed
(swollen) and consequently not functioning
properly.

13. HIV Encephalitis
Human Immunodeficiency Virus (HIV) can affect the
brain in different ways.
• HIV-meningoencephalitis is infection of the brain and
the lining of the brain by the HIV virus. It occurs
shortly after the person is first infected with HIV
and may cause headache, neck stiffness, drowsiness,
confusion and/or seizures.
• HIV-encephalopathy (HIV-associated dementia) is the
result of damage to the brain by longstanding HIV
infection. It is a form of dementia and occurs in
advanced HIV infection.
• Mild Neurocognitive Disorder is problems with
thinking and memory in HIV, however is not as severe
as HIV-encephalopathy. Unlike HIV-encephalopathy it
can occur early in HIV infection and is not a feature of
Aquired Immune Deficiency Syndrome - AIDS.

14. Encephalitis Lethargica
• Encephalitis Lethargica (EL) is a serious sporadic
form of Encephalitis.
• a form of encephalitis caused by a virus and
characterized by headache and drowsiness leading to
coma.
• The term "sleeping sickness", where people seem to
fall asleep or freeze whilst eating or working was
first used to describe two cases in Vienna.

15. SYMPTOMATOLOGY

16. Initial Signs
• Headache
• Malaise
• Anorexia
• Nauseaand Vomiting
• Abdominal Pain

17. S
ymptoms
• Fever
• Headache
• Behavioral changes
• Altered level ofconsciousness
• Focalneurological deficits
• seizures

18. Developing Signs

21. Possible Complications
• Permanent brain damage may occur in severe
casesof encephalitis. It canaffect:
Hearing
Memory
Muscle control
Sensation
Speech
Vision

22. DIAGNOSIS

23. DIAGNOSIS
• Because the various types of encephalitis produce
similar symptoms, doctors cannot rely on clinical
features to differentiate among the many causes of
brain inflammation. The primary objective in
diagnosing viral encephalitis is to determine if it is
caused by:
• Herpes simplex or other conditions that can be
treated with specific medications
• Arbovirusesorothervirusesthat can be
managed only by targeting symptoms

24. IMAGING TECHNIQUES
• For suspected encephalitis scanning technique is often
the first diagnostic step.
• Computerized tomography (CT)or magnetic resonance
imaging (MRI)scans can show the extent of the
inflammation in the brain and help differentiate
encephalitis from other conditions. MRIs are
recommended over CT scans because they can detect
injuries in parts of the brain that suggest infection with
herpes virus at the onset of the disease, while CT scans
cannot.
• Electroencephalogram (EEG),which records brain
waves, may reveal abnormalities inthetemporal lobe
that are indicative of herpes simplex encephalitis.

25. CEREBROSPINAL FLUID TESTS
• When encephalitis is suspected, a sample of
cerebrospinal fluid istaken using a lumbarpuncture.
• The sample istaken to count white blood cells and
identify specific blood cell types, to measure proteins
and blood sugar levels, and to determine spinal fluid
pressure.
• Doctors use CSF to test for herpes simplexvirus,Epstein-
Barrvirus,varicella-zoster virus,enteroviruses, and to
look for the presence of antibodies to the WestNile virus.
• While cerebrospinal fluid tests may help diagnose
encephalitis, they cannot provide information on how
severe the diseasewill be.

26. BLOOD TESTS
• Blood tests may be used to test for West Nile virus
and other arbovirusinfections.
• Blood and urine tests are used to isolate and
identify viruses.
• Enzyme-linked immunosorbentassays (ELISA),
including IgM-capture ELISA(MAC-ELISA) and IgG
ELISA, can identify viruses that cause encephalitis
soon after infection.
• Polymerase chain reaction (PCR) can identify small
amounts of viralDNA.

27. BRAIN BIOPSY
• Tiny samples of brain tissue are surgically removed
for examination and testing for the presence of the
virus.
• Tissue is prepared usingstaining techniques and
then viewed under an electron microscope.
• In a few cases, the viruses in brain cells are able to
be cultured; that is, the viruses can actually be
made to replicate in samples.
• A brain biopsy is thegold standard fordiagnosing
rabies.

28. TREATMENT
• 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.
Medications may include:
• 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)
Antibiotics --if the infection is caused by certain bacteria
Anti-seizuremedications (such as phenytoin) --to prevent
seizures.
Steroids(suchas dexamethasone) --to reduce brain swelling
(in rare cases)
Sedatives --to treat irritability or restlessness
Acetaminophen --for fever and headache.

29. TREATING PROBABLECAUSES OF
ENCEPHALITIS
• Since it isdifficulttodetermine thecause of encephalitis, and
rapid treatment isessential, clinical guidelines recommend
immediately administering intravenously the antiviraldrug
acyclovir without waiting to determine the cause of the illness.
• Once the doctor receives results from diagnostic tests, drug
treatment depends on the cause of the encephalitis. Antiviral
drug treatments for specific causes of encephalitis include:
•
•
•
Herpes Simplex Virus . Acyclovir isrecommended.
Varicella-Zoster Virus . Acyclovir isrecommended.
Ganciclovir or adjunctive corticosteroids may also be
considered.
Epstein-Barr Virus . Corticosteroids may be used,
although risksmay outweigh benefits. (Acyclovir isnot
recommended.)
• For bacterial meningitis,antibiotics (notantiviraldrugs)are
used.

30. ADDITIONAL TREATMENTS
• Other encephalitis treatments are aimed at
reducing symptoms.
• Seizures may be prevented by using oral
anticonvulsant drugsorintravenous lorazepam
(Ativan).
• Sedatives may beprescribed for irritability or
restlessness.
• Simple pain relievers may be used for fever and
headache.

31. Prognosis
• Acute phase of illness different from person to
person
• Some recover with slight disability, others
profound disability and a few need residential
care for a life time
• Degree and type of damage
cause of inflammation
severity of the infection
area affected
delay in seekingtreatment

32. Recent trends
Extensivefrontalgray mattervolume reduction related toa
possible sequalae ofencephalitis (Evernsel&etal, 2015)
39 year old man
Normal growth till 2years
At 2, a febrile illness with convulsions- unconscious for a week.
No treatment given
Could walk only at 5, no speech, lacking self-care,
disorganized behavior and mental retardation
Untreated encephalitis at 2 years damaged frontal region

36. Thank You