CNS Infections Flashcards
Most common route of spread of CNS infections include?
Hematogenous spread (arterial)
Routes of spread of CNS infection
Hematogenous - (Arterial)
Direct implantation (Traumatic)
Local extension - (Established infection or air sinus)
Axonal transport - (Rabies, herpes zoster)
Based on etiology and clinical evolution of illness, infectious meningitis is broadly classified into?
- Acute Pyogenic meningitis (bacterial)
- Aseptic meningitis (Acute, Subacute Viral)
- Chronic meningitis (Tuberculosis, spirochetal and cryptococcal )
Aseptic (Viral) meningitis is most commonly caused by?
Enterovirus causes leptomeningeal inflammation (pain and arachnoid mater)
- self limiting, low mortality, treat symptomatically
Type of inflammatory cells seen in Aseptic meningitis ?
- Lymphocytic infiltration
Clinical manifestation: Fever, meningioma irritation, depressed consciousness
Causes of Acute purulent meningitis in NEONATES ?
Neonates;
*Group B strep, E. coli
Causes of Acute purulent meningitis in Infants and children?
- Streptococcus Pneumoniae
- Haemophilus influenzae (reduced with immunization)
Causes of Acute purulent meningitis in Adolecents and young adults ?
- Neisseria meningitidis
Causes of Acute purulent Meningitis in Elderly?
- Listeria monocytogenes
- Streptococcus pneumoniae
Microscopic view of Acute purulent meningitis ??
Neutrophilic infiltration of the leptomeninges, extending variably to the cortex
Gross findings in Acute purulent meningitis?
- Opaque Leptomeninges
- Engorged meninges vessels
- Purulent exudates
- Diffused cerebral edema: Flattened and widened gyri with narrowed sulcus
Clinical presentation of Acute purulent meningitis?
Headache
Fever
Nuchal rigidity
photophobia
Irritability
Cloudy sensorium
Coma and death
Sequelae due to purulent exudate and fibrosis
- Hydrocephalus and cranial nerve impairment (neural deafness)
Bacteria with affinity for the base of the brain?
- Mycobacterium tuberculosis
- Cryptococcus species
Mycobacteria meningoencephalitis is caused by??
- Mycobacterium tuberculosis
- Atypical bacteria
Mycobacteria meningoencephalitis features
- usually involves the basal surface of the brain
- tuberculoma within the brain and dura mater
- common in aids patients
Which microbacterium is associated with AIDS Patients?
Mycobacterium avium intracellulare (MAI)
Normal CSF values in humans?
WBCs - < 5 lymphocytes cells
/uL
Glucose - 45-85 ug/dL (50 -70% glycemia)
Proteins - 15 - 45 mg/dl
Pressure - 70 - 80mmH20
CSF findings in Bacterial meningitis
WBCs - up to 90,000 neutrophils cells/uL
Glucose- < 45ug/dL (Decreased)
Proteins - > 50 mg/dL (increased)
Pressure - markedly elevated
CSF findings in Aseptic (viral) meningitis
WBCs - 100 - 1000cells/uL (lymphocytes)
Glucose - 45 - 85 ug/dL (Normal)
Protein - > 50mg/dL (increased)
Pressure - slightly elevated
cSF findings in Granulomatous meningitis (mycobacterial/fungal)
WBCs -100 - 1000 cells/uL
Glucose - < 45ug/dL (decreased)
Protein - > 50mg/dL
Pressure - moderately elevated
Protein is normal is one what type of meningitis ?
Aseptic (viral meningitis)
Common features of Viral encephalitides ?
- Perivascular cuffs of lymphocytes
- Microglial nodules
- Neuron loss
- Neuronophagia
Specific forms of viral encephalitides ?
- Arthropod borne
- Herpes simplex type 1 - hemorrhagic necrosis
- Rabies - Negri bodies
- HIV
- Progressive multifocal leucoencephalopathy
Negri bodies are found in purkinje and and hippocampal of what form of viral encephalitides?
Rabies
Cowdry bodies are seen where?
In Herpes simplex type 1; They are hemorrhagic necrosis of the temporal lobes
Arthropod born viral encephalitides?
- St Louis
- California
- Eastern and western equine
- Venezuelan
The diagnostic histologic findings in rabies?
Negri bodies in a purkinje or hippocampal cell
What part of the brain is involved in HIV and what complex does it form?
Cerebral involvement
- AID-Demetia complex
Histopathology of HIV encephalitides ?
Microglial nodules and diagnostic Myltinucleated giant cells
Spinal involvement in HIV leads to ?
Vascular myelopathy
(Similar to VB12 deficiency - associated with subacute combined degeneration)
What virus is associated with Progressive multifocal leukoencephalopathy (pML) ?
- Related to JC virus - A polyomavirus
- causes pML in immunocompromised patients (especially AIDS)
PML histopathology ?
- Demyelination
- lymphohistiocytic infiltrates
- Astrogliosis (bizarre shaped Astrocytes)
- oligodendrocytes (enlarged intranuclear inclusions)
Subacute Sclerosing panencephalitis is a rare complication of?
Measles (Rubeola) virus infection
persistent immune resistant measles virus causes slow-virus encephalitis
A child who had measles before age 2
* 6-15yrs later, presents with progressing mental deterioration with siezures*
fatal in 1-2 years once it develops
Most frequent agents causing Fungal meningoencephalitides?
- Candida
- Aspergillous
- Cryptococcus
- Mucor species
Aspergillus** and **mucor** have a marked tropism for **blood vessels
(Vasculitis, hemorrhage)
Cryptococcus cause what type of CNS pathology ?
Diffuse meningoencephalitis; invasion of the brain through virchow-robin space and soap-bubble lesions
Soap-bubbles lesions are associated with what type of infection?
Cryptococcus meningoencephalitis
Infections frequent in aids patient??
- pML
- Toxoplasmosis
Characteristic findings in toxoplasmosis ?
Central abscess with central necrosis and chronic inflammation
Neurosyphilis is a manifestation of what stage of syphilis ??
- Tertiary syphilis
- 10% of individuals with untreated syphilis
Major pattern of CNS involvement in neurosyphilis are;
1) Meningovascular neuropsyphilis
2) paretic neurosyphilis
3) Tabes dorsalis
Meningo-vascular neurosyphilis is associated with ?
- Obliterating endarteritis - heubner arteritis
- perivascular plasma lymphocytic infiltrates
- cerebral gummas
General paresis of the insane is associated with what pattern of neurosyphilis ?
- Paretic neurosyphilis
insidious but progressive of grandeur that terminate in severe dementia
Paretic neurosyphilisostly affects what part of the cerebral cortex?
The frontal lobe
- loss of neurons
- proliferation of microglia
- gliosis
- iron deposits
What structures are damaged in tabes dorsalis ?
Damage to the sensory axons or the dorsal roots
Microscopy:
Loss of both axons and myelin in the dorsal roots, pallor and atrophy in the dorsal columns of the spinal cord.
- locomotor ataxia: impaired joint position sense and ataxia
- Charcot joints: loss of pain sensation leading to skin and joint damage
- Lightening pain
- Absent deep tendon reflexes
Predisposing factors to cerebral abscess?
- Acute bacterial endocarditis
- Cyanotic’ heart disease
- Chronic pulmonary abscess
- Mastoiditis, paranasal sinusitis, acute otitis, open fracture, previous neurosurgery
MRI/CT appearance of cerebral abscess ?
Ring enhancing lesion
signs of increased intracranial pressure
Examples of a prion disease?
- Cruetz feldt Jakob disease (CJD)
- Kuru disease
- scrapie (sheep is host)
- Gerst Mann straussler disease
- Fatal familial insomnia
CRuetZfeldt Jakob disease results in what change ?
Spongiform change
fine vacuolization of the neutrophil in the gray mater (especially cortex)
Large membrane bound vacuoles within the neuronal processes
Associated with neuronal loss and astrogliosis
What are Kuru plaques ?
Deposits of amyloid of altered prp proteins. Seen using PAS stain
ECG changes in CJD?
Bilateral synchronous periodic epileptiform discharges (BIPEDs)?
- Death withing 6-12 months
- genetic predisposition
Memory loss with Startle myoclonus is associated with what prion disease?
CJD
Prion disease are generally associated with what CNS disease ?
Subacute spongiform encephalopathy SSE
What grieve is associated with kuru disease?
New Guine; consuming infected cattle brains
Scrapie is gotten from?
Sheep, scrapping their wool off on fences
Characteristic findings in several CNS infections
1) Viral encephalitis - Microglial modules, perivascular cuffs, neuronal loss, neuronophagia
2) Rabies - Negri bodies
3) HIV - Microglial nodules with multinucleated giant cells
4) Neurosyphilis - cerebral gummers
5) Cryptoccocus, aspergillosis and candida in Fungal meningoencephalitides - bubble lessions
6) JC virus in PML - Demyelination, lymphohistiocytic infiltrates, astrogliosis and oligodendroglial inclusions
7) CRuetZfeldt Jakob disease prion - Subacute spongiform encephalopathy (SSE)
8) Rubeola virus; Subacute sclerosing panencephalitis (SSPE)
9) Cerebral abscess; Ring enhancing lesions on MRI
10) Toxoplasmosis - ring enhancing lesion
11) Herpes simplex virus 1 - Cowdry bodies Hemorrhagic necrosis of temporal lobes.
12) Polo virus - affects the anterior horn
