Infections of the CNS Flashcards by Tom O

Symptoms of Acute Meningitis

Fever, HA, malaise, lethargy, nausea, vomiting, nuchael rigidity, impaird consciousness, Brudzinski or Kernig signs

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Which is more severe–bacterial or viral meningitis?

Acute bacterial meningitis more severe and may be fatal

Viral meningitis is benign, nonfatal, untreatable, but resolves spontaneously

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How does a bacterial infection reach the CNS?

Trauma

Hematogenous spread from distant site

Directly from adjacent infection (otitis, sinusitis)

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What test should be performed ASAP if you suspect bacterial meningitis?

Lumbar puncture

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How will CSF appear if the patient has bacterial meningitis? Protein, glucose, cells?

Cloudy CSF, High protein, Low glucose, lots of PMNs

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How will CSF appear if the patient has viral meningitis? Protein, glucose, cells?

Normal appearance, normal-high protein, normal glucose, lots of lymphocytes

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How should bacterial meningitis treatment be initiated?

Start with broad spectrum ABX until you know the causative agent, then switch to more specific ABX

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What are some potential complications of bacterial meningitis?

Hydrocephalus from pus obstructing CSF

Secondary inflammation and edema of cortex (meningoencephalitis)

Infarction from thrombosis of inflamed superficial vessels

Deafness

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Who is most likely to suffer form chronic meningitis?

Elderly

Malnourished

Immunocompromised

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Symptoms of chronic meningitis

Mild headache or confusion

No obvious meningeal signs

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What is encephalitis? What may cause it?

Primary infection and inflammation of brain, often viral

Caused by…HSV1, WNV, Polio, Varicella Zoster, HIV

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Herpes simplex encephalitis

What organism causes it and where in the brain will it likely infect?

Caused by HSV-1

Predilection for frontal and temporal lobes

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Herpes simplex encephalitis

How is it treated?

Acyclovir (antiviral drug)

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West Nile Virus

What is the spread? Symptoms?

Spread to humans by mosquitoes

Encephalitis (fever, headache, rash)

Weakness of the peripheral nerves or anterior horn cells

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Poliovirus

Where does it infect and what does it cause?

Infects motor neurons in the brainstem and spinal cord

Could cause mild regional weakness to general paralysis

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Shingles

What is the clinical manifestation?

Reactivation of Varicella-Zoster virus latent in the dorsal root ganglia

Vesicular rash with severe neuralgic pain along 1-2 dermatomes

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HIV

How is it acquired? What is it’s MOA?

Transmitted by infected body fluid (intercourse, needle sticks, blood products)

HIV destroys CD4 T cells, which can lead to AIDS

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AIDS dementia

What is it? What is seen on imaging?

Slow cognitive and behavioral decline with poor prognosis

Nonspecific atrophy and white matter alterations on MRI

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PML

Caused by what virus? What is its clinical manifestation in the CNS?

JC Virus

Patchy demyelination in the CNS and focal deficits

Toxoplasmosis

How is it acquired? What is seen on brain CT?

Acquired by ingestion of cat feces containing ova

See ring enhancing lesions on CT

What 3 symptoms are associated with congenital toxoplasmosis?

Chorioretinitis

Hydrocephalus

Intracranial calcifications

What bacterial infections of the CNS are most common in neonates?

E coli

GBS

Listeria

Pseudomonas

What bacterial infections of the CNS are most common in babies 1-12 months?

S. pneumo

H flu

What bacterial infections of the CNS are most common in age 1-16?

Neisseria meningitidis

S pneumo

H flu

What bacterial infections of the CNS are most common in age 16-50?

S pneumo N meningitidis

What bacterial infections of the CNS are most common in the elderly?

Listeria Pseudomonas

Tuberculous Meningitis | What is seen on histology?

Necrotizing granulomatous inflammation with epithelioid histiocytes, T cells, and multinucleated giant cells

Describe the CSF in Tuberculoid Meningitis

Mostly lymphocytes, Moderately high protein, Mildly low glucose

Cryptococcus Meningitis is most likely to occur in...

Immunocompromised

Cryptococcus Meningitis How would you confirm this infection?

On biopsy, see clear yeasts with a mucoid capsule in the perivascular (Virchow Robbins) space Done with mucicarmine or India Ink stain

How might Angioinvasive Aspergillus appear on histology?

On GMS stain, see dark fungi with hyphae branching at 45 degree angles

How does Cysticercosis appear on brain imaging?

See empty cystic spaces filled with scolex

Naegleria fowleri | How is the infection acquired? What does it cause?

Swimming in freshwater lakes, the amoeba enters and penetrates the cribiform plate to cause Acute Fulminant Meningoencephalitis (often fatal)

What are the microscopic findings of viral encephalitis?

Perivascular inflammation Leptomeningeal inflammation Microglial nodules Neuronophagia

What is neuronophagia?

Dead neurons surrounded by microglial cells and histiocytes Seen in viral encephalitis

Rabies Virus | Transmission? Incubation? Histology?

Transmitted from rabid animals (bats, raccoons) Incubation can last 10 days-1 year depending on bite location Histology: NEGRI BODIES (cytoplasmic inclusions)

CMV | What are some complications of CMV Encephalitis?

Large intracytoplasmic and intranuclear inclusions Hydrocephalus Many foci of calcifications seen in white matter

HIV encephalitis | Describe where it is seen and what cells may be involved

Widespread microglial nodule encephalitis with multinucleated giant cells with predilection to grey matter

HIV Leukoencephalopathy | Describe where it is seen and what cells may be involved

Diffuse white matter myelin pallor with microglial nodules and multinucleated giant cells

Vacuolar Myelopathy | Describe where it is seen and what cells may be involved

Spastic paraparesis with hyperreflexia and ataxia Vacuolation of spinal cord white matter Resembles subacute combined degeneration

Brain Abscess | What is it? How does it appear on MRI?

Focal discrete CNS infection Appears as a ring enhancing lesion on MRI

Brain Abscess | What are the 4 stages of evolution of an abscess?

Early cerebritis Confluent necrosis Early encapsulation Late encapsulation

Brain Abscess | Treatment

Surgical excision (if there is one) Antibiotics

Prion Disease | What are the two main prion diseases?

Cruetzfeld Jakob Disease (CJD) Bovine spongiform encephalopathy (BSE)

Prion Disease | MOA

Misfolded proteins induce conformational changes in normal proteins Neuronal death occurs WITHOUT inflammation

Cruetzfeld Jakob Disease (CJD) | Symptoms

``` Dementia Prominent myoclonus (jerky contractions of muscle groups) ``` CST, extrapyramidal, LMN signs

Cruetzfeld Jakob Disease (CJD) | Histology

Spongiform changes (cytoplasmic vacuoles in neurons and astrocytes) Neuronal death without inflammation