CNS Infections Flashcards
What is another name for a leptomeningeal inflammation?
meningitis
What are the types of penchymal inflammation?
encephalitis, cerebritis, myelitis
brain abscess
What is another name for subdural or epidural inflammation?
subdural/epidural empyemas
How does infection get into the brain?
arterial spread retrograde venous spread local extension (air sinuses, infected tooth) neural route (PNS--->CNS) direct implantation (trauma, iatrogenic)
What does the word neurotropism mean?
having a special affinity for nervous tissue
What is the most common cause of meningitis?
strep pneumo
What are the clinical signs/symptoms of meningitis?
headache, photophobia, stiff neck (nuchal rigidity), clouded consciousness, fever
What are the 4 clinical types of meningitis?
hyperacute 1 wk
aseptic
What are the key features of hyperacute meningitis?
meningococcal meningitis (n. gonorrhea) sparse inflammation, numerous organisms, congestion
Waht are the key features of acute meningitis?
usually bacterial
from hematogenous spread
exudate present, numerous PMNs in subarachnoid space
What are the key features of subacute/chronic meningitis?
TB, syphillis
brain parenchyma commonly affected as well
lymphocytes, plasma cells, macrophages in exudate
What are the key features of aseptic meningitis?
usually viral
much less fulinant than bacerial meningitis and less severe sx
summer and early fall
lymphocytic infiltrate in meninges
What are come complications of bacterial meningitis?
brain infarcts
phlebitis (which may cause infarction of underlying brain tissue)
secondary vasculitis
What organisms commonly cause aseptic meningitis?
arboviruses
enterovirus (most common) [echovirus, coxsackie]
What are the clinical signs/sx of brain abscesses?
focal deficits, raised IC pressure
What are brain abscesses usually caused by in immunecompetent hosts?
strep
staph
How do brain abscesses like to spread?
toward the ventricles
What are some common abscess cuasing pathogens in immunocomprimised hosts?
toxoplasma nocardia listeria gram neg bacilli mycobacteria fungi
What is encephalitis?
inflammation of brain parenchyma
if in spinal cord-myelitis
if meninges and brain-meningoencephalitis
What are common causes of bacerial meningoencephalitis?
TB
syphilis
Lyme disease
What do you find in the CSF with TB meningoencephalitis?
elevated pressure and protein
decreased glucose
lymphocytic pleocytosis
cultures for AFB positive in 50%
What are signs and symptoms of TB in the CNS?
headache
lethargy
confusion
vomiting
What does TB in the CNS look like on gross examination?
mass lesion with central necrotic core or caseation, surrounded by fibroblasts, epitheliod histocytes, giant cells and lymphocytes
What is another name for TB osteomyelitis?
spondylitis/pott’s disease
What is TB osteomyelitis?
granulomatous process involving vertebral bodies and discs
causes epidural abscesses
can lead to cord compression & vertebral collapse
Describe neurosyphilis?
tertiary states
months-yrs after initial infection
What are the major forms of neurosyphilis?
general paresis (paretic neurosyphilis) meningovascular tabes dorsalis
What are the key features of general paresis?
gradual impairment of cognition/attention
thickened meninges and atrophic brain
meningeal & parenchymal perivascular lymphocytes, plasma cells, microglia
What are the key features of meningovascular type neuropyphilis?
chronic meningitis and multifocal arteritis
severe at base of brain
causes infarcts and hydrocephalus
meningeal & arrterial/arteriolar lymphocytes and plasma cells with collagenous thickening of wall and eventual occlusion
focal neuro deficits due to vascular compromise 2ary to arteritis
What are the key features of tabes dorsalis?
chronic inflammation in dorsal roots and ganglia w/loss of neurons and assoc. deg of posterior columns
“lightening pains” or paraesthesias in affected roots, loss of position/vibratory sense, shuffling broad based gait
What are key general features of viral (meningo)encephalitis?
perivascular lymphocytes
microglial nodules
neurnophagia
What specific organisms commonly cause viral meningoencephalitis?
arobvirus
herpes virus
HIV
progressive multifocal leukoencephalopathy
Which virus is the most common cause of psoradic acute viral encephalitis in temperate climates?
HSV1
What are signs of HSV infection in the CNS?
headache, fever, modd, memory, behavior abnormalities, drowsiness, coma
What is seen in HSV1 CNS infection on MRI?
focal abnormalities in frontal or temporal lobes
What is seen in the CSF with a HSV1 CNS infection?
increased pressure
lymphocytic pleocytosis
elevated prtein
PCR for HSV1 DNA
What are gross findings of acute HSV encephalitis?
congestion, swelling, hemorrhagic necrosis of temporal lobs, insula, cingulate gyri, orbital cortex
What is the most common opportunist viral infection in AIDS patients? What does it cause?
CMV
subacute encephalitis
What demographic most commonly gets HSV2 meningitis?
neonates passing through birth canal in mother with active HSV2 infection
What are the signs/symptoms of arboviral meningoencephalitis?
seizures, confusion, stupor, delirium, coma & focal signs
What types of arboviral meningoencephalitis are common in the US?
west nile easter, western equine venezuelan st louis california
How does HIV infection enter the CNS?
by infecting microglia
What are the types of HIV involvement in the CNS?
HIV meningitis
HIV encephalitis/leukoencephalopathy
vacuolar myelopathy
When does HIV meningitis occur?
during acute flu-like illness at time of seroconversion
What are the clinical signs and symptoms of HIV encephalitis/leukoencephalopathy?
AIDS demential complex-cognitive and behavioral deterioration, eventually dementia, ataxia and tremor
What classic lesion is seen in HIV encephalitis/leukoencephalopathy?
microglial nodules containing multinucleated (giant) microglial cells (contain HIV virus)
What are hte key features of progressive multifocal leukoencephalopathy?
immunosuppressed hosts
caused by JC virus, which infects oligodendrocytes
JC virus infection during adolescence, reactivated w/immunosuppression
What are the histologic findings associated with PML?
enlarged oligodendrocyte nuclei immunostained for JC virus, at ege of area of early myeloin loss
oligodendrocyte inlcusion
irregular porrly defined areas of demyelination
What gross examination findings are associated wiht PML?
small foci of gray discoloration in white matter
What is seen on gross examination of cerebral toxoplasmosis?
mutliple localized necrotic lesions
What histologic findings are seen with cerebral toxoplasmosis?
tissue necrosis
toxo organisms lying free in tissue
organisms within pseudo cytes
Who gets cerebral toxoplasmosis?
fetus if infection occurs during pregnancy
immunocompromised hosts, esp AIDS pts
What are common fungal pathogens that can cause meningoencephalitis in immunocompromised hosts?
candida, mucor, aspergillus, cryptococcus, histoplasma, coccidiodes, blastomyces
Which fungi will most commonly cause secondary vasculitis?
aspergillus and murcor
What does aspergillus brain infection look like?
multiple foci of hemorrhagic necrosis with brain necrosis with inflammation
may see vessel wall infiltration by fungal hyphae
Where does cryptococcus spread to the brain from?
the lungs
What are the main forms of cryptococcus in the CNS?
meningitis with or without brain parenchymal cysts (encephalitis)
abscesses (cryptococcomas)
What CSF findings are present with fungal infection?
lymphocytes, hihg protein, normal or reduced glucose
What does cryptococcus infection look like on gross exam?
thickened meninges, esp over the sulci
multiple intraparenchymal cysts “soap bubbles”
What histologic findings are seen in cryptococcal meningitis?
organisms are single round year forms surrounded by capsule
minimal inflammatory reaction
What parasites besides toxoplasma can cause CNS infection?
amoeba
plasmodium (malaria)
trypanosoma
cystercercus (taenia solium)
What causes most epidural and subdural empyemas?
staph and strep
via: frontal or mastoid sinusitis, otitis media, trauma, osteomyelitis or surgery
In what case can a CSF profile be misleading?
if tx already started
Which organism that causes meningitis also casues skin pettechiae?
neisseriea menigitidis
What populations does listeria monocytogenes cause menigitis in?
neonates, elderly, immunocomp.
also in alcoholics
When is e. coli meningitis seen?
in neonates, nosocomial
If a patient has AIDS and meningitis sx for a few weeks what organisms do you suspect?
1) crypto
2) TB
If someone presents with a less severe form of meningitis in the summer what organisms do you think may be causing?
enterovirus/aseptic
If you suspect meningitis what do you do?
LP
If CSF has increased WBC count and left shift what do you suspect?
bacterial infection
If CSF has high mononuclear count what do you suspect?
fungus or TB
What do increased lymphocytes in the CSF usually indicate?
fungus
If glucose in the CSF is normal what do you suspect?
viral cause
Which type of Abx MUST you use for meningitis?
CIDAL!!
What is the tx of choice for s. pneumo meningitis?
IV ceftriaxone
What is a good initial therapy for bacterial meningitis?
IV ceftriaxone, vancomycin, corticosteroids
What abx is added if listeria suspected?
ampicillin
What immunizations are available to try to prevent bacterial meningitis?
for pneumococcus, meningococcus and h influenza
If you suspect viral meningitis but patient presents in summer what do you have to think of?
arboviruses
What bacterial meningitis more commonly presents in summer?
lyme disease
What pathogens are at the top of your ddx in a patient with focal neurologic deficits?
JC
toxoplasma
If a patient has menigitis symptoms have been slowly worsening over a few months what type of disease do you have to include on the ddx?
prion disease
Does syphilis present with acute or chronic meningitis?
can present with either
