Infections of the CNS Flashcards
Why is the incidence of meningitis decreasing?
Hib, pneumococcus, and meningococcus A, C, W135, Y vaccines
Where is bacterial meningitis located?
In the subarachnoid space. In very severe cases, swelling can affect cortex
What is the pathogenesis of bacterial meningitis?
Bloodstream, adjacent intracranial infection, skull/spinal defects
What
Increased BBB permeability, leading to swelling and higher ICP.
Severe disease can cause vasculitis or infarction
Interferes with CSF circulation (hydrocephalus)
Pron-inflammatory cytokines lead to edema
What is the classic triad with meningitis?
fever, depressed consciousness, stiff neck
Also: h/a, CNS findings
What is the Kernig sign?
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What is the ?????sign?
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When should antibiotics be started in meningitis
within 60 minutes of arriving to emergency room
What is the workup fo meningitis?
blood cultures, LP, empiric antibiotics, neuroimaging
What is the key diagnostic procedure for bacterial meningitis?
LP Open P: 200-500 CSF pleocytosis: 1000-5000 %PMNs >80% Protein: 100-500 (high due to inflammation) Glucose
What is the sensitivity of gram stain?
60-90%
What is the sensitivity of LP?
70-85%
When should a lumbar puncture not be performed prior to neuroimaging?
Get blood cultures and begin empiric antibiotics before neuroimaging
Don’t want to cause herniation
Focal neurologic deficit/altered consciousness
Signs of ICP (papilloedema)
Suspected focal CNS infection/lesion
Immunocompromised (more worried about CNS lesions)
What neuroimaging should be done?
Whichever is faster. MRI is slightly better
What are the most likely bugs involved in meningitis during the neonatal period?
Group B strep E. coli Strep pneumoniae (pneumococcus) Neisseria Meningitidis (meningococcus) Listeria Monocytogenes (early or late in life, alcoholics- requires ampicillin)
What are the most likely bugs involved in meningitis during ages 2-23 months?
Group B strep E. coli H. Flu Strep pneumoniae (pneumococcus) Neisseria Meningitidis (meningococcus)
What are the most likely bugs involved in meningitis during ages 2-35 years?
Neisseria Meningitidis (meningococcus) Strep pneumoniae (pneumococcus)
What are the most likely bugs involved in meningitis during over 35 years?
Strep pneumoniae (pneumococcus) Neisseria Meningitidis (meningococcus) Listeria Monocytogenes (early or late in life, alcoholics- requires ampicillin)
What is the empiric therapy for bacterial meningitis in neonates?
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What is the empiric therapy for bacterial meningitis in children >2 months?
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What is the empiric therapy for bacterial meningitis in adults?
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Intracellular gram negative diplo cocci?
Meningococcus
What are the gram stain findings for the different bacteria types involved in meningitis
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When should steroids be intiated
Before starting antibiotics. Usually dexamethasone given prior to or simultaneously with first dose of antibiotics
What are some complications of acute bacterial meningitis
Someone gets better, then starts getting worse
Decline in consciousness:
meningoencephalitis
Cranial nerve palsy (most often VIII)
Seizures or nonconvulsive status epilepticus
Subdural empyema
acute hydrocephalus
cerebral infarcts due to septic arteritis or endarteritis obliterans, venous thrombophlebitis, thromboemboli
When should you repeat LPs?
Not getting better, PCN resistant pneumococcus, gram negative rods and listeria
What are the main causes of viral meningitis?
Enteroviruses, HSV-2
Also: VZV,
What are the main causes of viral encephalitis?
WNV, HSV-1
What does the CSF look like with a viral CNS infection?
Mostly lymphocytes (PMNs early in some-WNV)
normal glucose
normal protein
PCR positive
What is the treatment for enterovirus?
No FDA approved therapy
What does the CSF look like with a viral CNS infection?
Mostly lymphocytes (PMNs early in some-WNV)
normal glucose
normal protein (elevated in HSV)
PCR positive
What are clues that the virus is enterovirus?
rash, pharyngitis/herpangina, GI, pleurodynia, myocarditis, pericarditis, conjunctivitis
What is the treatment for HSV meningitis?
Valacyclovir or acyclovir
What is the most common cause of encephalitis
HSV
What is autoimmune encephalitis?
Anti-NMDA receptor encephalitis- CSF profile looks like viral encephalitis.
How does HSV cause encephalitis?
HSV hangs out in the trigeminal ganglion. Can possibly go up the olfactory nerve to the bulb. Also possibly for sensory tract.
What are the signs and symptoms of HSV encephalitis?
Altered consciousness, fever, h/a, seizures, focal signs (less common)
How does acyclovir work?
Viral tyrosine kinase phosphorylates acyclovir making it active
What are arboviruses?
Spread by mosquitos and ticks- WNV, zika virus
What happens with WNV?
Virus infects local inflammatory cells, and spreads infection along the inflammatory pathway, spreading to the lymph nodes.
What symptoms are associated with WNV meningoencephalitis?
Fever, h/a, nuchal rigidity
nausea, vomiting, neck pain
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What symptoms are associated with WNV meningoencephalitis?
Fever, h/a, nuchal rigidity
nausea, vomiting, neck pain, myalgia
low back pain
tremor
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What does imaging look like in WNV and HSV
MRI is very sensitive for HSV - frontal or temporal lobes, but WNV MRI looks completely normal- will cause issues in deep grey nuclei
Where are the MRI findings in the different viral meningitis?
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How is WNV detected?
IgM serology. CSF IgM antibody for WNV. cross-reacts with yellow fever, zika
How is HSV detected?
PCR
What does CSF look like in WNV?
Pleocytosis up to >2000 cells
PMNs can predominate early
Reactive lymphocytes
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What is the therapy for WNV?
Not much.
How can you be exposed to toxoplasmosis?
Eating cat poop
What is the presentation of toxoplasmosis?
h/a, fever, confusion, lethargy, seizures, or focal neurologic signs
How do you diagnose toxoplasmosis?
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How do you treat toxoplasmosis?
bactrim or sulfa-based therapy
What organisms cause basilar meningitis?
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How do you diagnosis cryptococcus?
CSF cryptococcal antigen (CRAG)
What is the clinical presentation of cryptococcus?
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What does CSF look like in cryptococcus?
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What is the treatment for cryptococcus?
Amphoterecin and fluconazole
Make sure LP opening pressures continue to decrease
