Encephalopathy => cerebral dysfunction due to circulatory toxins, poisons, abnormal metabolites. Intrinsic biochemical disorder affecting neurons without inflammatory response Inflammation of meninges – meningitis Involvement of brain parenchyma – meningoencephalitis

1. ACUTE CNS INFECTION
P.POOJA SWETHA
MBBS IV YEAR

2. INTRODUCTION
Encephalopathy => cerebral dysfunction due to
circulatory toxins, poisons, abnormal
metabolites.
Intrinsic biochemical disorder affecting neurons
without inflammatory response
Inflammation of meninges – meningitis
Involvement of brain parenchyma –
meningoencephalitis

3. ETIOLOGY OF ENCEPHALOPATHIES
Infections
Acute disseminated encephalomyelitis
Postinfectious : typhoid, shigella, Reye syndrome
Hypoxic encephalopathy, heat hyperpyrexia
Metabolic : diabetic acidosis, uremic coma, hepatic coma,
neonatal hyperbilirubinemia, lactic acidosis, mitochondrial
disorders, inborn error of metabolism
Fluid and electrolyte disturbances: water intoxication,
hypernatremia, hyponatremia, alkalosis, acidosis
Toxic: heavy metals, insecticides, carbon monoxide
Post vaccination

4. ACUTE BACTERIAL MENINGITIS

5. AGE AND INCIDENCE
Age: – 90% between 1month to 5 yrs
Incidence: – 5.4 to 7.3/1,00000 population
Decreased after use of conjugate Hemophilus
Influenza b vaccine

6. ETIOLOGY
Depends on
Age
Immune Status of the host
Environmental factors

7. ETIOLOGICAL ORGANISMS
NEONATAL PERIOD:
Group B streptococcus,
Gram negative enteric organisms,
Listeria monocytogenes, Hemophilus influenza.
2MONTHS ‐12YRS:
Hemophilus influenza(<5yrs),
Streptococcus pneumoniae, Neisseria meningitidis,
Rarely : Staph.aureus, S.typhi, Pseudomonas

8. RISK FACTORS
Lack of immunity
Close contact with invasive disease caused by He
mophilus influenza, Neisseria meningitidis.
Overcrowding
Occult bacteremia in infants

9. PREDISPOSING FACTORS AND
ORGANISMS

10. ROUTES OF SPREAD
Blood spread
• pneumonia
• Cochlear
implant,
osteomyelitis
Direct spread
• Trauma,
neuro surgery
• sinusitis
Others
• Csf
rhinorrhea
• Myelo
menigocele

11. PATHOGENESIS
Meninges infiltrated with inflammatory cells
Cortex shows edema , proliferation of microglia,
destruction of ependymal cells.
PATHOLOGICAL CHANGES
Exudate
Subpial toxemia
Vasculitis and thrombosis

12. EXUDATES
Sites of collection
• Cerebral vessels
• Sylvian fissures
• Base and
surface of brain
• cerebellum
Manifestations
• Meningeal
irritation
• Raised ICT
Complications
• Internal
hydrocephalus
• Neurodeficits

13. VASCULAR CHANGES
Subintimal changes in the small vessels & arte
ries,
Thrombosis and
thrombophlebitis of small cortical veins,
Subarachnoid haemorrhage,
Hemiparesis due to ischemia

14. SUBCELLULAR PATHOGENIC MECHANISM
Subpial toxemia: TNF and cytokine production
Bacterial pathogen release endotoxin and
peptidoglycans => extensive host damage
Cerebral edema
Cytotoxins-
cytotoxic edema
Increased
vascular
permeability-
vasogenic edema

15. DIFFERENTIAL DIAGNOSIS OF MENINGITIS
Tubercular meningitis
Viral encephalitis
Meningism
Aseptic meningitis
Cryptococcal meningitis
Lyme disease
Subarachnoid hemorrhage

16. TUBERCULAR MENINGITIS
Tuberculosis -major global health problem
2nd leading cause of death among
infectious disease worldwide ‐ after HIV
In 2013 –9.0 million new TB cases &
1.5 million TB deaths
Infection of the CNS is one of the most devastating clini
cal manifestations of tuberculosis

17. EPIDEMIOLOGY
Approximately 95% of tuberculosis cases occur in the devel
oping world.
Worldwide (2013) ‐‐ 8.7 million incident cases,
‐‐ 12 million prevalent cases,
‐‐ 1.4 million deaths from tuberculosis
India accounts for 1/5 of the global TB burden
The global burden is influenced by the HIV pandemic; MDR
TB;
Most common between 6 and 24 months of age

18. ETIOPATHOGENESIS
 TB Bacillemia (primary or late reactivation)
 Subependymal tubercles
Rupture into the subarachnoid space
Meningitis

19. ENCEPHALITIS
Inflammation of brain parenchyma
ETIOLOGY
RNA viruses : mumps, measles, rubella, enterovirus
DNA viruses : HSV , CMV , EBV
Arthropod borne viruses: JE, west nile, equine virus
HIV, Rabies, prion infections , dengue virus
Lymphocytic meningitis
Rickettsia; cryptococcus; toxoplasma

20. THANK YOU