9 Central Nervous System INFECTIONss.ppt

CNS infection

1. CNSCNS

2. CNS INFECTIONS
•Five categories
•1- Acute bacterial(pyogenic) or viral(a septic)
meningitis
•2- subdural empyema or brain abscess
•3- chronic bacterial meningitis
•4- fungal and parasitic infections
•5- acute, subacute and chronic viral encephalitis

3. Route of entry
• Hematogenous spread
•by way of the arterial blood supply is the most common means of
entry.
• Direct implantation
• due to traumatic introduction of foreign material.
•In rare cases it can be iatrogenic(LP)
• infections of the skull or spine.
•Sources include air sinuses, most often the mastoid or frontal;
infected teeth; cranial or spinal osteomyelitis; and congenital
malformations
• Peripheral nerves in particular, viruses such as the rabies
•and herpes zoster

4. Acute Bacterial meningitis
•The pathogen differ according to age groups :
• neonate( E.coli+group B streptococci) _
•infants (S pneumoniae +H influenzae)
• adults (N gonorrhoea , S pneumoniae and Lmonocytogenes)
• Morphology : CSF is cloudy purulent with neutrophils and
microorganism , meningeal vessels engorgement , hemorrhagic
infarctions in chronic cases leptomeningeal fibrosis could be
seen that may lead to hydrocephalus.
•Clinically pt present by headache ,photophobia , irritability,
clouding of consciousness and neck stiffness. lP shows
turbulent CSF under increase pressure with elevated proteins
and decrease glucose.

8. Acute a septic (viral) meningitis
•is mainly caused by enteroviruses
•usually self limited
• meningeal irritation, fever, and alterations in
consciousness of relatively acute onset
• characterized by irritation brain swelling, lyphocytosis of
CSF and moderate protein elevation.

9. Brain Abscess
•CEREBRAL ABSCESSES
–Local (mastoiditis, sinusitis)
–Hematogenous (tooth extraction, sepsis)
–Staph, Strep
–Often fibrous capsule, liquid center
•SUBDURAL EMPYEMA (IN SINUSITIS)
•EXTRADURAL ABSCESS
(IN OSTEOMYELITIS)

10. Brain Abscess
•Morphology: central region of liquefactive necrosis,
fibrosis surrounded by gliosis and marked cerebral
oedaema.
•Clinically : progressive focal deficit ,
•signs of raised ICP, CSF pressure,
• cell count and protiens increases glucose is
normal ,
•the source of infection may be apparent , abscess
rupture may lead to dissaminated infection and
thrombosis.

14. CHRONIC BACTERIAL
Meningo-encephalits
•TB mainly in immunocomromized pts may lead to
fibrosis and endarteritis
•Neurosyphilis; in the tertiary stage of syphilis usually in
untreated pts leading to progressive mental deterioration
and dementia. The risk of Neurosyphilis increased by
AIDS.
•Tabes dorsalis due to spirochete damage to the sensory
nerve leading to axonal loss and demylination ( ataxia,
loss of pain sensation, skin and joint damage called
Charcot joint) .
•Lyme disease: tick prone disease presented as a septic
meningitis, encephalopathy and poly neuropathy caused
by borrelia burgdorferi)

15. TUBERCULOMA

16. VIRAL
Meningo-encephalitis
•Usually it is parenchymal infection associated with meningeal inflammation
•Viral infections have wide spectrum of clinical and pathological presentations but
characteristically there is MNC infiltration, microglial nodules, neuronophagia
ARBO VIRUSES (West Nile, Equines, Venez., many more)
•HSV1
•HSV2
•V/Z
•CMV
•POLIO
•RABIES
•HIV
•Progressive Multifocal Leukoencephalopathy (JC)
•Subacute Sclerosing Panencephalitis (Measles).

17. VIRAL
ENCEPHALITIS
PERIVASCULAR
LYMPHOCYTIC
“CUFFING”

19. PERIVASCULAR
GIANT CELLS
in WHITE MATTER in
HIV
ENCEPHALITIS

20. FUNGAL
MENINGO-ENCEPHALITIS
•Common in immunocompromized due to hematogenous spreed
•Most common organisms are cadida, aspirogellus,
cryptococcus neoformance, histoplasma .
•It causes 3types of infections:
•1- chronic meningitis
•2- vasculitis
•3-barenchymal involvment with granuloma formation
•Other parasitic infections includes toxoplasmosis and
Amebiasis
(Mostly in immunocompromised hosts)

21. SUBACUTE SCLEROSING
PANENCEPHALITIS (SSPE)
•VERY rare since measles eradicated
•Thought to be caused by measles virus

23. CRYPTOCOCCUS
MICROABSCESSES

24. OTHERS
•MALARIA
•TOXOPLASMOSIS (in HIV)
•AMEBIASIS
•TRYPANOSOMES
•RICKETTSIAE
•ECHINOCOCCUS

25. Colour Protein Glucos Cells
NORMAL Clear 0.45 g/L <60% of serum
glc or
>3.0 mmol/
0-5 WBC, 0
RBC,
0 PMNs
Viral infectionClear or
opalescent
Normal or
slightly
increased
)
<0.45-1 g/L
Normal
<1000x106/L
Lymphocytes
mostly,
some PMN
Bacterial
infection
Opalescent
yellow,
may clot
>1 g/L Decreased
(<25% serum
glc
or <2.0 mmol/L
>1000x106/L
PMNs
Granulomatous
infections(tuber
cuosis, fungal)
Clear or
opalescent
Increased but
usually
<5 g/L
Decreased
(usually
<2.0-4.0
mmol/L
1000x106/L
Lymphocytes