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