This document discusses encephalitis and encephalopathies in children. It begins with important definitions such as encephalopathy, acute encephalitis syndrome, encephalitis, and meningoencephalitis. It then discusses the types and etiologies of encephalitis including infectious causes such as viral, bacterial, parasitic and immune related causes as well as non-infectious causes. Specific conditions discussed in more detail include Japanese encephalitis, herpes simplex virus encephalitis, and metabolic encephalopathies. The document concludes with sections on the clinical features, investigations, management steps including empirical treatment and supportive care, and preventive strategies for encephalitis.

1. Encephalitis & Encephalopathies
in Children
• Dr.C.S.N.Vittal

2. Encephalopathy
Encephalopathy describes a clinical
syndrome of altered mental status,
manifesting as reduced consciousness
or altered behavior
Acute Encephalitis Syndrome (AES)
Acute onset of fever and a change in
mental status (including symptoms such
as confusion, disorientation, coma, or
inability to talk) AND/ OR new onset of
seizures (excluding simple febrile
seizures)
Encephalitis
Encephalitis means
inflammation of the brain.
Meningoencephalitis
Acute inflammatory process
involving the meninges and,
to a variable degree, brain
tissue
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IMPORTANT DEFINITIONS

3. Encephalitis - Types
Infectious Non-infectious
Viral
Eg. HSV, VZV, EBV,
Dengue, Measles,
Rabies
Bacterial
Eg. MTB, Listeria,
Mycoplasma, Lyme
Other
Eg. Malaria, Amoebic,
Scrub typhus, TBM
ADEM, Antibody mediated
(anti-NMDA type)
N-methyl-D-aspartate receptor

4. Etiology of AES
• Viral Encephalitis
– RNA Viruses: Mumps, measles, rubella, enteroviruses
– DNA Viruses: Herpes simplex, cytomegalovirus, Epstein-Barr virus
– Arthropod borne viruses: Japanese B encephalitis, West Nile, Russian
spring summer, Equine viruses
• Bacteria: Listeria, Lyme disease, Tuberculous meningoencephalitis
• Parasitic: Cerebral malaria, Amoebic encephalitis,
• Other: Rickettsia, Slow viruses, Prion infections
• Immune Related
– ADEM, HIV, Dengue

5. Non Infective Causes
Immune Metabolic
• Heavy metal, Cannabis,
Carbon monoxide
Encephalopathies
• Acute disseminated
encephalomyelitis
(ADEM)
• Postinfectious:
• Typhoid, Shigella,
• Reye syndrome
• Post-Vaccination
• Diabetic acidosis, Uremic
coma, Hepatic coma
• Neonatal hyperbilirubinemia,
Lactic acidosis, IEMs
• Mitochondrial disorders
• Fluid and electrolyte
disturbances
• Hypernatremia, Hyponatremia,
• Acid-Base disturbances
Toxic

6. Differences Between Encephalitis And
Encephalopathy
Parameter Encephalitis Encephalopathy
Headache Common Uncommon
Seizures Focal / Generalized Generalized
Focal signs Usually present Usually absent
Fluctuation Usual Steady
Liver dysfunction Common Uncommon
Leucocytosis Common Uncommon
CSF pleocytosis Common Absent
EEG Diffuse / focal Diffuse slowing
MRI Abnormal Usually normal

8. Encephalitis – Clinical Features
• Fever, headache, raised intracranial tension signs,
• Changes in alertness: drowsiness, lethargy, coma
• Seizures, speech disturbances, confusion
• Gait changes
• Skin rashes
• Neck stiffness
• Photosensitivity

9. Japanese Encephalitis (JE)
• Single stranded neurotropic RNA virus of Flaviviridae family
• Vector: Cules tritaenirrhynchus – breeds on rice fields
• Infection zoonotic with pigs and Ardeid birds as chief hosts
• Man is incidental dead-end host
• 1/4th cases in India
• High incidence in W.Bengal, Bihar, Assam, Orissa,
Pondycherry, Goa and MP
• Incubation period 5-15 days

10. Japanese Encephalitis (JE)
• Clinical presentations:
1. Abortive
2. Aseptic meningitis
3. Severe encephalomyelitis: with
or without radiculitis
• Sudden onset with high fever,
vomiting, mental confusion,
irritability and loss of
consciousness
• Stages:
1. Prodromal
2. Encephalitic
• Acute (3-4 days)
• Subacute (7-10 days)
3. Convalescence (4-7 weeks)

11. Japanese Encephalitis (JE)
Prevention:
• Anti-mosquito measures: Insecticidal sprays, larvicides, bed nets, repellants
• Vaccination:
– Mouse brain killed vaccine
– Live attenuated SA-14-14-2 vaccine (China)
– IC 51 vaccine – Ixiaro: Inactivated Vero cell culture-derived JE vaccine
– Indian Strain vaccine (821564 XZ) Kolar (JENVAC)
– Chimeric vaccine Live attenuated YFV-17D/JEV: With Pre-membrane and
envelope genes of yellow fever 17 D infectious clone

12. Herpes Simplex Virus (HSV) Encephalitis
• Leading cause of sporadic encephalitis
• Nonspecific prodrome of headache, fever and vomiting followed by altered
consciousness, focal or generalize seizures
• Focal neurologic signs – characteristic
• Movement disorders, stroke, behavioural disorders, hallucinations and
memory loss
• CSF: Pleocytosis
• Neuroimaging: Characteristic temporal lobe signal changes with MRI

13. Management Steps
Detailed History and Examination [SAMPLE]Step02
InvestigationsStep03
Empirical TreatmentStep 04
Supportive CareStep05
Rapid Assessment and Stabilization [ABCDE]Step01
Prevention/treatment of complications & rehabilitationStep06
Management Steps

14. Step 1: Rapid Assessment and Stabilization
• Airway:
– Establish and maintain :
– Intubate if…
• GCS<8, impaired airway reflexes
• abnormal respiratory pattern,
• signs of raised ICP,
• oxygen saturation <92% despite high flow oxygen, and
• fluid refractory shock
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15. Step 1: Rapid Assessment and Stabilization
• Breathing:
– Ventilation,
– Oxygenation
• Circulation:
– Establish IV access,
– take samples (CBC, Blood sugar, KFT, LFT, electrolytes, blood
gas, lactate, PS and RDT for malarial parasite, serology for
viruses),
– Fluid bolus if in circulatory failure (20 mL/kg NS),
– inotropes if required
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16. Step 1: Rapid Assessment and Stabilization
• Disability: refers to a child's neurologic function in terms of the level of
consciousness and cortical function.
– Identify signs of cerebral herniation or raised ICP
• Exposure: Examine undressed; as feasible!
– Temperature: treat fever and hypothermia
• Treat ongoing seizures- Benzodiazepine, followed by phenytoin
loading
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17. Step 2: Detailed History and Examination -
SAMPLE
• Signs & symptoms
– Fever, headache, vomiting, seizures, abnormal posturing
– Altered behavior, cognition, personality changes, altered consciousness
– Prodromal symptoms- flu-like illness, diarrhea
– Rash, vesicles, past history of chicken pox
• Allergies:
– for Drugs, foods, pets
• Medications:
– Drug or toxin exposure- enquire for presence of any drugs at home
– Cancer treatment, steroid/immunosuppressant treatment
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A
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18. Step 2: Detailed History and Examination -
SAMPLE
• Past pertinent medical history
– Diabetes, congenital heart disease, chronic kidney or liver disease
– Other concurrent systemic illness e.g. jaundice (hepatic failure), pneumonia
(hypoxic encephalopathy), diarrhea (dyselectrolytemia), dysentery (shigella
encephalopathy)
– Characteristics of some IEMs
– Residence of child: Rural/urban, endemic for cerebral malaria, any epidemic of
AES in neighborhood
– History of animal contact, insect bite, dog bite
– Personal or family history of seizure disorder
– Family history of previous infant/child deaths
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19. Step 2: Detailed History and Examination -
SAMPLE
• Last oral intake (Last menstrual cycle)
– Drug or toxin exposure- enquire for presence of any drugs at home
• Events leading to present illness
– Recent history of travel / History of trauma
– Recent immunizations
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20. Step 2: General Physical Examination
• Pallor - cerebral malaria, or intracranial bleed.
• Icterus - leptospirosis, hepatic encephalopathy, or cerebral malaria.
• Skin rashes - in meningococcemia, dengue, measles, varicella, rickettsial
diseases, arboviral diseases, and enteroviral encephalitis.
• Petechiae - in meningococcemia, dengue and viral hemorrhagic fevers.
• Parotid swelling and orchitis - mumps as etiology.
• Labial herpes in young children - herpes simplex virus encephalitis

21. Step 2: Neurological Examination
• A modified GCS should be used for infants and young children
• Pupillary size, shape, symmetry and response to light provide valuable clues to
brainstem and third nerve dysfunction.
• Unilateral pupillary dilatation in the comatose patient should be considered as
evidence of oculomotor nerve compression from ipsilateral uncal herniation
• Progressive symmetrical external ophthalmoplegia suggest Bickerstaff
brainstem encephalitis in association with M. pneumoniae, especially when
associated with ataxia

22. Step 2: Neurological Examination
• Personality changes, confusion and disorientation
– Herpes Simplex Encephalitis
• Presence of oculocephalic (doll’s eye), oculovestibular, corneal, cough and gag
reflexes:
– Brainstem dysfunction is an important feature in some causes of viral encephalitis such as
enterovirus 71, mumps, and rabies
• Associated acute flaccid paralysis
– enterovirus infections (anterior horn cell involvement),
– poliomyelitis (anterior horn cell involvement),
– acute disseminated encephalomyelitis (due to myelitis)

23. Step 2: Neurological Examination
• Myoclonic jerks
– seen frequently in enterovirus encephalitis
• Retinal hemorrhages
– an important clue for cerebral malaria in endemic setting
• Signs of meningeal irritation
– Meningitis
• Myocarditis
– an important complication of EV 71 encephalitis

24. Step 3: Investigations
• Basic investigations
– Complete blood count (including platelet count)
– Blood glucose, serum electrolytes
– Liver and kidney function tests
– Blood culture
– Arterial blood gas, and lactate
– A peripheral smear / rapid diagnostic test for malaria
– Chest x-ray should also be obtained

25. Step 3: Investigations
• Lumbar puncture: If the patient is hemodynamically stable, and no features
of raised intracranial pressure
• CSF should be examined for
– Cytology, biochemistry, Gram stain, Ziehl-Nielsen stain for acid fast bacilli, bacterial
culture, latex agglutination, PCR for HSV 1 and 2, and IgM antibodies for JE and for
Dengue virus (if suspected).
– Concurrent blood sugar must also be measured to look for the CSF to blood sugar ratio.
1-2 mL CSF should be stored for other virological studies,

26. What information should be gathered from the LP?

27. Step 3: Investigations - Neuroimaging
• CT scan:
– presence of bleed, cerebral edema,
– temporal lobe hypodensities in herpes simplex encephalitis,
– thalamic abnormalities in JE, and
– basal exudates and hydrocephalus in tubercular meningitis
– may also show brain herniation,
– effacement of cisterns, and
– infective collections such as brain abscesses and subdural empyema

28. Step 3: Investigations
MRI FINDINGS IN VIRAL ENCEPHALITIS AND SOME MIMICKERS
Etiology MRI Finding
Herpes simplex
encephalitis
Abnormal signal intensity in medial temporal lobe, cingulate gyrus, and orbital
surface of frontal lobes
Japanese B
encephalitis
Abnormal signal intensity in thalami (87-94%), substantia nigra, and basal
ganglia
Nipah virus Focal subcortical and deep white matter and gray matter lesions; small
hyperintense lesions in the white matter, cortex, pons and cerebral peduncles
have also been seen
Varicella Multifocal abnormalities in cortex, associated cerebellitis, vasculitis and
vasculopathy
Acute disseminated
encephalomyelitis
Multifocal abnormalities in subcortical white matter; involvement of thalami,
basal ganglia, and brainstem also seen

29. Role of brain biopsy in Encephalitis
No place in the initial assessment in immunocompetant children
• Stereotactic brain biopsy is indicated when:
– no diagnosis after the 1st week
– focal abnormalities on imaging
– if the findings could change the child’s management
• An open biopsy
– if imaging shows nothing focal
– from the non-dominant frontal lobe, may be preferable

30. Step 4: Empirical Treatment
• A broad spectrum antibiotic ceftriaxone must be given,
– which can be stopped if no evidence of bacterial meningitis is
forthcoming.
• Empirical anti-malarial (artemisin-based combination therapy)
must be started if there is a suspicion of cerebral malaria.
– This should be stopped if the peripheral smear and rapid
diagnostic tests are negative.

31. Step 4: Empirical Treatment
• Acyclovir must be started in all cases of sporadic viral encephalitis. It should be stopped if an
alternative diagnosis has been made, or HSV PCR in the CSF is negative and MRI is normal.
– Dose: 10 mg / kg IV infusion in 1 hr 8 hrly for 2-3 wks.
– Acyclovir resistant cases Foscarnet is the only drug available.
– Corticosteroids should not be used routinely in patients with HSV Encephalitis
• Cerebral edema
– Mannitol 1-2 gm/ Kg infuse quickly
– Glycerol orally
– Diuretics
– Steroids
– Elective hyperventilation

32. Step 5: Supportive Care
(a) Maintenance intravenous fluids: hypotonic fluids (e.g.Isolyte P) must be
avoided, especially in the presence of raised intracranial pressure
(b) Management of raised intracranial pressure:
(c) Maintain euglycemia
(d)Treatment and prevention of seizures
(e) Other
– Acid-base and electrolyte abnormalities should be corrected.
– Nosocomial infections must be prevented and treated promptly

33. Step 6: Prevention / treatment of
complications and rehabilitation
• Nosocomial infections, aspiration pneumonia
• Coagulation disturbances
• Myocarditis in EV 71 - milrinone
• Early physiotherapy

34. Step 6: Preventive Strategies
(i) Surveillance for cases of AES;
(ii) Vector control;
(iii) Reduction in man-vector contact;
(iv) Vaccination.

36. METABOLIC ENCEPHALOPATHIES
• Encephalopathy refers to altered mental status that includes “disorientation,
short-term memory impairment, inattentiveness and abnormal state of
arousal”
• Encephalopathy could result from lack of glucose, vitamin cofactors or
oxygen and end organ failure.
• Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J (eds). Harrisons Principles of
Internal Medicine. 19th Ed. New Delhi: Mc Graw Hill; 2015.

37. METABOLIC ENCEPHALOPATHIES
• ‘Metabolic encephalopathy refers to “clinical state of global cerebral
dysfunction induced by systemic stress varying in clinical presentation from
mild executive dysfunction to deep coma”
– Kinnier Wilson
• METABOLIC ENCEPHALOPATHIES #Sangeetha Yoganathan, Sayli Umakant *Bidkar Indian
Journal of Practical Pediatrics 2020;22(1) : 26-35

38. METABOLIC ENCEPHALOPATHIES - ETIOLOGY
Electrolyte
disturbances
hypernatremia, hypocalcemia, hypercalcemia, hypophosphatemia,
hypomagnesemia, hypermagnesemia
Inborn errors of
metabolism
Organic acidemia, urea cycle disorders, mitochondrial cytopathy
Organ failures Hepatic encephalopathy, uremic encephalopathy, hypoxic and hypercapnic
encephalopathy
Endocrine causes Hypoglycemia, diabetic ketoacidosis, adrenal crisis, hypothyroidism,
hyperthyroidism
Nutritional deficiency Wernicke encephalopathy
Miscellaneous Reye syndrome, Hypertensive,
Posterior Reversible Encephalopathy Syndrome (PRES)

39. Dys-electrolytemia related Encephalopathy
• Sodium less than 125 mmol/L (hyponatremia), sodium more than 160 mmol/L
(hypernatremia),
• Ionized calcium less than 0.5 mmol/L (hypocalcemia), ionized calcium more
than 3 mmol/L (hypercalcemia),
• Phosphorus less than 0.5 mmol/L (hypophosphatemia),
• Magnesium less than 0.5 mmol/L (hypomagnesemia) and magnesium more
than 2 mmol/L (hypermagnesemia)
Osmotic demyelination syndrome: with rapid correction of hyponatremia, malnutrition, burn injuries,
cirrhosis, pituitary surgeries, prolonged use of diuretics, hypophosphatemia and folate deficiency.

40. Hypoglycemic encephalopathy
• Hypoglycemia:
– Blood sugar < 50 mg/dL in neonates less than 48 hr
< 60 mg/dL after 48 hours of life
– may occur due to low birth weight, sepsis, hyperinsulinism,
inborn errors of metabolism, growth hormone deficiency,
adrenal insufficiency and medications.
– Symptoms in these patients include lethargy, headache,
seizures and altered sensorium

41. Inborn Errors of Metabolism (IEM)
– Clinical Clues
• Neurological
– Lethargy, coma, poor sucking, apnea, myoclonic seizures,
hypotonia or hypertonia, involuntary movements, hiccups,
fast breathing
• Gastrointestinal
– Hepatosplenomegaly, Cholestatic jaundice
• Others
– Hypothermia,
– Sepsis-like presentation with no response to antibiotics,
– Abnormal urine odor, dysmorphic features,
– Hydrops fetalis

42. Wernicke encephalopathy
• Results from thiamine deficiency
• The classical triad described in Wernicke encephalopathy
1. memory disturbances,
2. ataxia and
3. ophthalmoplegia are not observed in majority of cases

43. Hepatic encephalopathy (HE)
Etiology
• Chronic Liver Disease:
• Infections : Viral hepatits A, B, E
• Septicemia
• Drugs: INH, Acetaminophen, Sodium valproate, Carbon tetrachloride
• Wilson disease
• Autoimmune liver disease
• Acute Budd-Chiari syndrome
• Malignancies: Leukemia, Histiocytosis X, Lymphoma

44. Hepatic encephalopathy (HE)
West Haven grading
Grade Clinical features
1 • Lack of awareness
• Decreased attention span
• Impaired calculation
• Euphoria or anxiety
2 • Lethargy or apathy
• Disorientation of time or place
• Personality changes
• Inappropriate behavior
• Impaired calculation
3 • Hypersomnolence
• Disorientation
• Stupor
4 • Coma

45. Reye syndrome
Diagnostic criteria
• “Acute noninflammatory encephalopathy that is documented clinically by
a) an alteration in consciousness and
b) CSF containing less than or equal to 8 leukocytes/cu.mm or
c) a histologic specimen demonstrating cerebral edema without perivascular or
meningeal inflammation.
• Hepatopathy documented by either
a) a liver biopsy or an autopsy considered to be diagnostic of Reye syndrome
b) a threefold or greater increase in the levels of ALT / AST or serum ammonia.
c) No more reasonable explanation for the cerebral and hepatic abnormalities

46. Posterior Reversible Encephalopathy Syndrome
(PRES)
• In children and adults with uncontrolled hypertension of varied etiology,
– use of immunosuppressive drugs and antiretroviral drugs,
– blood transfusion,
– hypercalcemia,
– eclampsia,
– thrombotic thrombocytopenic purpura,
– hemolytic uremic syndrome,
– von Hippel Lindau disease and exposure to contrast media

47. Posterior Reversible Encephalopathy Syndrome
(PRES)
• Possible mechanisms
– impaired cerebrovascular autoregulation,
– endothelial damage and
– vasogenic edema
• Symptoms include headache, vomiting, seizures, lethargy,
somnolence, stupor, coma, visual disturbances and focal motor
deficits

48. MANAGEMENT
• 1. General measures:
– Maintain euglycemia, correct dyselectrolytemia if identified and supplement
thiamine or other vitamin cofactors
– Antiepileptic medications must be chosen appropriately
– Raised intracranial pressure if identified must be managed appropriately
– Strict control of hypertension and elimination of precipitating factors

49. MANAGEMENT
• 2. Specific measures and organ support
a) The management of hepatic encephalopathy involves
– maintenance of fluid and electrolyte balance and euglycemia.
– protein restricted diet to decrease the blood ammonia levels
– use of antibiotics such as ampicillin and metronidazole
b) Hemodialysis or peritoneal dialysis may be useful in selected cases.
c) With Reye syndrome
– maintain the cerebral perfusion pressure and
– supportive measures such as 10% dextrose infusion,
– raised ICP management and correction of hyperammonemia

50. MANAGEMENT
• 2. Specific measures and organ support
d) Adrenal crisis:
– Volume expansion with IV fluids and
– correction of hyponatremia and hypoglycemia.
– Hydrocortisone (100 mg/m2/day) as infusion or bolus in the first 24
hours and may be gradually tapered to oral maintenance doses.
– Treatment of infection.
e) Diabetic ketoacidosis:
– appropriate intravenous fluids,
– insulin infusion and correction of dyselectrolytemia

51. Points to Remember
• Metabolic encephalopathy should be suspected in any child with altered
consciousness after excluding CNS infection, structural disorders, toxin
ingestion and trauma.
• Organ or system failure like hepatic encephalopathy, hypoxia,
dyselectrolytemia and endocrine dysfunction are responsible for metabolic
encephalopathy.
• Underlying etiologies are diverse which can be narrowed down by
recognizing the clinical clues.
• Management includes acute stabilization and specific measures based on
etiology including organ support.

52. • Dr.C.S.N.Vittal