CNS infections Flashcards
what organisms cause meningitis in neonates from exposure during delivery
- E-coli
- Group B strep
what organisms that colonize the nasopharynx (sinusitis, otitis media, mastoiditis) cause meningitis
- S. pneumo
what organisms are prevelant in crowded conditions that cause meningitis
- N. meningitidis
what organisms cause meningitis after head trauma
- staph
most common pathogens causing meningitis in ages 3 months - 55 years
- S. pneumonia
- H. influenza
- N. meningitides
meningitis causes which results in increased ICP and decreased cerebral perfusion
cerebral edema
classic triad of meningitis
- fever
- nuchal rigitidity
- altered mental status
what tests test for nuchal rigitidy
- kernigs sign
- brudzindki’s sign
- jolt accentuation test
jolt accentuation test
- rotate head quickly back and forth
- positive: headache gets worse
which pathogen which causes meningitis is associated with petechiae and palpable purpura
- N. meningitidis
kernig’s sign
- inability or reluctance to allow full extension of knee when hip is flexed at 90 degrees
Brudzinski’s sign
- spontaneous flexion of hips during attempted passive flexion of neck
diagnostic evaluation of meningitis
- blood cultures x 2 (before abx)
- CT scan?
- LP
- labs
- CBC, cmp, ESR, CRP
what glucose findings in CSF is consistent with bacterial meningitis
- decreased glucose in CSF (< 40)
when should you order a CT scan prior to a LP
- immunocompromised
- hx of CNS dz
- new onset sz
- papilledema
- ALOC
- focal neurological deficit
if mass lesion or evidence of increased ICP is present on CT, there is a risk of when performing LP
cerebral herniation
treatment for meningitis
- do not delay tx
- empiric IV abx immediately after LP
- if LP delayed, begin abx after blood cultures obtained
tx for newborn with meningitis
- ampicillin + cefotaxime
tx for person aged 1 month-50 yrs with meningitis
- third gen cephalosporin (ceftriaxone) + vancomycin
tx for person aged > 50 yrs with meningitis
- ceftriaxone + ampicillin + vancomycin
tx for immunocompromised person with meningitis
- cefepime + ampicillin + vancomycin
why is dexamethasone used as adjuvant in tx of meningitis
- decreases rate of hearing loss and decreases morbidity and mortality
- particularly with pneumococcal meningitis
- initiate before or at same time as abx therapy
when should you continue to use dexamethasone as adjuvant in tx of meningitis? what should you consider adding
- only continue if gram stain or blood culture + for S. pneumoniae
- consider adding Rifampin if steroid continued
vaccinations are available for which pathogens that can cause meningitis
- S. pneumoniae
- N. meningitidis
- H. influenzae
meningitis post exposure prophylaxis
- ceftriaxone
what is aseptic meningitis
-
viral meningitis
- clinical evidence of meningeal inflammation but bacterial cultures are negative
most common cause of viral meningitis
- enterovirus
viral meningitis presents similarly to bacterial meningitis with added
- viral type symptoms
- diarrhea
- URI
- myalgias
diagnostic evaluation of viral meningitis
- blood cultures x 2 (before abx)
- CT?
- LP
- CBC, CMP, ESR, CRP
what glucose findings in CSF is consistent with viral meningitis
- normal glucose 40-80
tx of viral meningitis
- self-limited, tx is symptomatic: analgesic, antipyretic
- abx are started at presentation and discontinued once bacterial meningitis ruled out
CSF WBC count expected in viral and bacteria meningitis
- viral: < 500
- bacterial: > 1,000
CSF protein expected in viral and bacteria meningitis
- viral: 15-45
- bacterial: 100-500
differentiate between meningitis and encephalitis
- meningitis: preservation of cerebral function
- encephalitis: abnormalities in brain function
- can be blurred: meningoencephalitis
define encephalitis
- acute inflammation of brain
what is primary infection encephalitis
- due to viral invasion of CNS
- neuronal involvement
what is post infectious encephalitis (Acute disseminated encephalomyelitis)
- immune mediated, no virus detection
- neurons spared
- typically occurs at initial infection is resolving
what is the most common cause of fatal encephalitis
- herpes simplex virus
what is the most common cause of encephalitis
- west nile virus
photophobia and nuchal rigidity are rare with encephalitis but may be seen with
meningoencephalitis
clinical presentation
- fever
- headache
- AMS
- Sz
- focal neurological deficits (hemiparesis, CN palsies, inc DTR)
encephalitis
encephalitis caused by west nile virus will present with
- flaccid paralysis and rash
diagnostic evaluation of encephalitis
- blood cultures x 2
- CBC, CMP
- CSF PCR for HSV-1, HSV-2, and enteroviruses
- IgM antibody testing for West nile virus
imaging study of choice for encephalitis
- MRI
- temporal lobe changes suggestive of HSV
tx of encephalitis
- acyclovir
- HSV is the most important to identify and treat
- Sz prophylaxis and control
two types of epidural abscess
- intracranial (IEA)
- spinal (SEA)
two etiology types causing CNS abscess
- direct spread: otitis media, meningitis, head trauma
- hematogenous spread: pulmonary, skin, intraabdominal infection
90% of CNS abscesses are caused by
bacteria
immigrants can get cerebral abscess caused by
- parasites
- cysticercosis due to Taenia solium
clinical presentation
- usually nonspecific
- unilateral headache
- fever
- nuchal rigidity
- AMS
- focal neurological deficits
- Sz
cerebral/intracranial abscess
diagnostic evaluation of CNS abscess
- blood cultures x 2
- CBC, CMP
imaging of choice for CNS abscess
- MRI
- will show a ring-enhanced lesion
- necrosis after 2 weeks
- will show a ring-enhanced lesion
treatment of CNS abscess
- CT guided aspiration or surgical excision
- abx empiric
- 4-8 weeks
imaging of choice for spinal epidural abscess
- MRI - ASAP
- neurologic changes can become permanent
most common cause of spinal epidural abscess
-
staph aureus > 60%
- consider MRSA
diagnostic evaluation of spinal epidural abscess
- blood cultures x 2
- CBC with diff, CMP
tx of spinal epidural abscess
- CT guided aspiration or sugical excision
- abx x 4-8 weeks
-
vancomycin +
- cephalosporin
-
vancomycin +
