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CNS infection
Dr. V.P.C.Rajakaruna MBBS(COLOMBO)
Content
• Types of infections
• Causative agents
• Symptoms and signs
Infections – Terminology
• Meningitis • Encephalitis• Myelitis• Meningoencephalitis• Meningomyelitis• Encephalomyelitis• Meningo-encephalomyelitis• Brain abscess
Meningitis
Meningitis
• Purulent meningitis
- polymorphonuclear cell
- WBC > 1000 celss/mm3
- pyogenic bacteria• Lymphocytic meningitis• Eosinophillic meningitis
- eosinophil > 5%
- parasite• Carcinomatous meningitis
Pathogenic organism• Virus• Bacteria• Mycobacterium• Fungus – Cryptococcus neoformans• Parasite – Angiostrongylus cantonensis, Gnathostomiasis,
Cysticercosis• Actinomycosis • Protozoa• Rickettsia• Spirochete• Mycoplasma
Pathogenesis
• Hematogenous spreading• Parameningeal structures – sinusitis, mastoiditis,
otitis media, dental carries• Direct infection to the subarachnoid space –
fracture base of skull, dermal sinus tract, ruptured meningoceal abscess
• Direct infection – surgery, lumbar puncture• Cranial nerve and peripheral nerve – rabies
encephalitis, herpes simplex encephalitis
Symptoms and signs
• Fever, Headache, Nausea and vomitting• Period
- acute period: within 1 week
bacteria, virus, amoeba, parasite,
systemic infection
- subacute period: 1- 4 weeks
tuberculosis, fungus, parasite,
spirochete, systemic infection
- chronic period: > 4 weeks
Chronic meningitisInfectious causes
M.Tuberculosis
Cryptococus neoformans
Cysticercosis
Angiostrongylus cantonensis
Treponema pallidum
Nocardia asteroides
Actinomycosis
Acanthamoeba
Noninfectious causes
Neoplasm
SLE
Vasculitis
Behcet’s disease
lymphocytic meningitis
Sjogren’s syndrome
Symptoms
Symptoms (children)
Kernig’s sign
Brudzinski’s sign
Symptoms
• Alteration of consciousness
• Seizure
• Localizing signs: hemiparesis, paraplegia
• Cranial nerve palsy
• Autonomic hyperactivity
Investigations
Lumbar puncture
Lumbar puncture
CSF analysis• The characteristics of normal CSF
- open pressure: 50-200 mmCSF
- clear color
- cells: RBC
WBC- lymphocyte < 5 cells
- protein 20-45 mg/dl
- CSF sugar/ Serum sugar > 50%
- fresh smear, Gram stain, India ink,
AFB, modified AFB
- culture
CSF analysis for differential diagnosis (acute onset)
Pathogen Virus Bacteria
Open pressure Normal Normal, increased
Appearance Clear Turbid
WBC + (+)
Lymphocyte
+++
PMN
Protein + ++
CSF sugar/ Serum sugar
Normal Decreased
Others Special lab Gram stain, culture, CIE, latex agglutination
CSF analysis for differential diagnosis (acute onset)
Pathogens Parasite Protozoa (Naegleria)
Systemic infection
Open pressure
Normal, increased
Normal, increased
Normal
Appearance Angio: coconut juice
Gnatho: xanthochrome
Turbid Clear
WBC ++
eosinophil
+++
PMN
+Lymphocyte
Protein ++ ++ +
CSF sugar/ Serum sugar
Normal Decreased Normal
Others - Fresh smear, culture
-
CSF analysis for differential diagnosis (subacute onset)
Pathogen Tuberculosis Cryptococcosis
Open pressure Normal, increased
Normal, increased
Appearance Straw color
Xanthochrome
Clear
WBC + +
Lymphocyte
++
Lymphocyte
Protein +++(+) ++
CSF sugar/ Serum sugar
Decreased Decreased
Others AFB, culture, cobweb, PCR
India ink, culture, Crypto Ag
Viral Encephalitis
HSV encephalitis
• In adult most caused by HSV-1• Primary infection in oropharyngeal or intranasal
mucosa• Latent ganglionic infection• Reactivation leads to encephalitis • Headache, fever, alteration of consciousness
VZV encephalitis
• After varicella develop, VZV remain within the ganglia
• Reactivation, spread to spinal cord & brain
Japanese encephalitis
• Flavivirus, Culex- borne, Southeast Asia /China• Symptoms: headache and alteration of
consciousness• Clinical signs (post encephalitis): tremor, dystonia,
rigidity, mask-like face• Mortality rate 30%• Vaccine available – inactivated virus, age should be
more than one year to get the vaccine
Rabies encephalitis
• Rhabdovirus family, transmission through dog bites
• Encephalitic form involve cerebrum, brainstem
• Late state involve basal ganglia and thalamus coma
• Paralytic form involve medulla, spinal cord
CMV encephalitis
• Opportunistic infection in organ transplant, HIV
• Brainstem encephalitis, cranial nerve palsy, associated retinitis visual pathway