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

Purulent meningitis - polymorphonuclear cell - WBC > 1000 celss/mm 3 - 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 meningitis Infectious 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

CSF analysis The characteristics of normal CSF - open pressure: mmCSF - clear color - cells: RBC WBC- lymphocyte < 5 cells - protein mg/dl - CSF sugar/ Serum sugar > 50% - fresh smear, Gram stain, India ink, AFB, modified AFB - culture

CSF analysis for differential diagnosis (acute onset)

PathogenVirusBacteria Open pressureNormalNormal, increased AppearanceClearTurbid WBC+ (+) Lymphocyte +++ PMN Protein+++ CSF sugar/ Serum sugar NormalDecreased OthersSpecial lab Gram stain, culture, CIE, latex agglutination

CSF analysis for differential diagnosis (acute onset)

PathogensParasiteProtozoa (Naegleria) Systemic infection Open pressure Normal, increased Normal Appearance Angio: coconut juice Gnatho: xanthochrome TurbidClear WBC++ eosinophil +++ PMN + Lymphocyte Protein++ + CSF sugar/ Serum sugar NormalDecreasedNormal Others- Fresh smear, culture -

CSF analysis for differential diagnosis (subacute onset)

PathogenTuberculosisCryptococcosis Open pressureNormal, increased AppearanceStraw color Xanthochrome Clear WBC+ Lymphocyte ++ Lymphocyte Protein+++(+)++ CSF sugar/ Serum sugar Decreased OthersAFB, 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