Infections of the CNS Flashcards
Symptoms of Acute Meningitis
Fever, HA, malaise, lethargy, nausea, vomiting, nuchael rigidity, impaird consciousness, Brudzinski or Kernig signs
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
How does a bacterial infection reach the CNS?
Trauma
Hematogenous spread from distant site
Directly from adjacent infection (otitis, sinusitis)
What test should be performed ASAP if you suspect bacterial meningitis?
Lumbar puncture
How will CSF appear if the patient has bacterial meningitis? Protein, glucose, cells?
Cloudy CSF, High protein, Low glucose, lots of PMNs
How will CSF appear if the patient has viral meningitis? Protein, glucose, cells?
Normal appearance, normal-high protein, normal glucose, lots of lymphocytes
How should bacterial meningitis treatment be initiated?
Start with broad spectrum ABX until you know the causative agent, then switch to more specific ABX
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
Who is most likely to suffer form chronic meningitis?
Elderly
Malnourished
Immunocompromised
Symptoms of chronic meningitis
Mild headache or confusion
No obvious meningeal signs
What is encephalitis? What may cause it?
Primary infection and inflammation of brain, often viral
Caused by…HSV1, WNV, Polio, Varicella Zoster, HIV
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
Herpes simplex encephalitis
How is it treated?
Acyclovir (antiviral drug)
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
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
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
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
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
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
