3- CNS Infections Flashcards
Causative agent of bacterial meningitis if exposure during delivery?
E. coli, Group B strep
Causative agent of bacterial meningitis if sinusitis, otitis media, mastoiditis?
S. pneumo
Causative agent of bacterial meningitis if military, college (crowded conditions)?
N. meningitides
Causative agent of bacterial meningitis if head trauma?
Staph spp
Causative agent of bacterial meningitis if post-neurosurgical procedure?
Staph spp, gram (-)
What are the 2 most common causative agents of bacterial meningitis?
N. meningitides (meningococcal)
S. pneumoniae (pneumococcal)
Pt presents with fever, nuchal rigidity, AMS, and HA +/- photophobia, N/V. On PE you note (+) jolt accentuation test. What CNS infection are you concerned for?
(jolt accentuation test - pt rotates head horizontally 2x / second, (+) = exacerbation of existing HA)
Bacterial meningitis
On PE of pt with CNS complaint, you note petechial rash and palpable purpura. What condition/ causative agent are you concerned for?
Bacterial meningitis; N. meningitidis
(meningococcal rash)
Late findings of what CNS infection include papilledema, and (+) Kernig’s and Brudzinski’s sign?
Bacterial meningitis
What diagnostics are ordered for all cases of meningitis and encephalitis?
Blood cultures x 2 (before abx)
LP
Labs
+/- CT
What is the gold standard for dx of bacterial meningitis?
CSF culture
According to the following CSF analysis, what CNS infection are you concerned about?
WBC > 1,000
Glucose < 40
CSF/ blood glucose < 0.4
Protein 200-500 (elevated)
Gram stain (+)
Neutrophils present
Bacterial meningitis
According to the following CSF analysis, what CNS infection are you concerned about?
WBC < 500
Glucose 40-80
CSF/ blood glucose 0.6
Protein 15-45
Gram stain (-)
Lymphocytes present
Aseptic meningitis
According to the following CSF analysis, what CNS infection are you concerned about?
WBC < 250
Glucose 40-80
CSF/ blood glucose 0.6
Protein- elevated < 150
Gram stain (-)
Lymphocytes present
Viral encephalitis
A CT is recommended before LP in patients with 1+ of which RFs? (6)
- IMC
- Hx of CNS disease
- New onset seizure
- Papilledema
- Abn level of consciousness
- Focal neuro deficit
Gram stain of pt with CNS infection shows G (+) diplococci. What is the likely pathogen?
Pneumococcal
Gram stain of pt with CNS infection shows G (-) diplococci. What is the likely pathogen?
Meningococcal
Gram stain of pt with CNS infection shows G (-) coccobacilli. What is the likely pathogen?
H. influenzae
Gram stain of pt with CNS infection shows G (+) rods and coccobacilli. What is the likely pathogen?
L. monocytogenes
What is the tx for bacterial meningitis after blood cultures and LP?
Dexamethasone + empiric IV abx
Pt with bacterial meningitis was started on dexamethasome + empiric IV abx. Gram stain or blood cultures come back (+) for S. pneumoniae (pneumococcal meningitis). What is the next step in tx?
Continue dexamethasone + add Rifampin
When do you NOT prescribe vancomycin in the tx of bacterial meningitis?
Newborn
When do you NOT prescribe ampicillin in the tx of bacterial meningitis?
1 month- 50 yrs
Basilar skull fracture (contiguous spread)
Penetrating trauma/ post-neurosurgery (contiguous spread)
*when you do NOT suspect L. monocytogenes*
When do you NOT prescribe dexamethasone in the tx of bacterial meningitis?
Newborn
How do you proceed with tx of bacterial meningitis if LP is contraindicated?
Continue empiric abx + dexamethasone
How do you proceed with tx of bacterial meningitis if no bacteria is seen on Gram stain but other CSF findings are consistent with bacterial meningitis?
Continue empiric abx + dexamethasone
DIC, ARDS, septic shock +/- impaired mental status/ cognition and sensorineural hearing loss are complications a/w what CNS infection?
Bacterial meningitis
How is bacterial meningitis prevented?
Vaccines
Post-exposure prophylaxis (N. meningitides)- Cipro, Rifampin, Ceftriaxone
What is the most common cause of aseptic meningitis?
Enterovirus
(HSV-2 also common)
Pt with recent travel hx (ticks, TB) or sexual activity (HSV-2, syphilis, HIV) is more likely to have what CNS infection?
Aseptic meningitis
Pt presents with aseptic meningitis sxs + diffuse, maculopapular exanthem and is mildly ill. Suspected etiology?
Enteroviral infection, primary HIV, syphilis
Pt presents with aseptic meningitis sxs + oropharyngeal thrush and cervical LAD. Suspected etiology?
Primary HIV
Pt presents with aseptic meningitis sxs + asymmetric flaccid paralysis. Suspected etiology?
West Nile virus
What is included in the management for aseptic meningitis?
Empiric abx (until r/o bacterial meningitis)
Supportive tx
Acyclovir if severe/ IMC
Are abnormalties in brain function more common with meningitis or encephalitis?
Encephalitis
What type of encephalitis is due to direct viral invasion of the CNS and has (+) neuronal involvement?
Primary encephalitis
What type of encephalitis is there NO virus detected, neurons are spared, and may be a/w perivascular inflammation/ demyelination?
Post infectious encephalitis (acute disseminated encephalomyelitis- ADEM)
(typically occurs as initial infection is resolving)
What is the most common cause of fatal encephalitis?
HSV-1
What is the most common cause of vital encephalitis (in the US)?
Mosquitos/ West Nile virus
(Africa, Asia, Europe, US)
Coxsackie, HSV-2, HIV, mumps, and measles are more commonly a/w meningitis or encephalitis?
Meningitis
West Nile virus, HSV-1, CMV, and influenza are more commonly a/w meningitis or encephalitis?
Encephalitis
Pt presents with HA, fever, AMS, and seizures, and on exam seems to be confused, agitated, and obtunded. Pt denies photophobia and nuchal rigidity. PE shows focal neuro deficits (hemiparesis, CN palsies, increased DTRs). What CNS infection are you concerned for?
Encephalitis
(photophobia and nuchal rigidity more a/w meningeal involvement so can be seen w/ meningoencephalitis)
Pt presents with encephalitis sxs + hydrophobia, hyperactivity, and pharyngeal spasms. Suspected etiology?
Rabies
Pt presents with encephalitis sxs + tremors of the tongue, lips, and eyelids. Suspected etiology?
St. Louis virus
LP of pt with suspected encephalitis shows RBCs and decreased glucose in CSF. What etiology are you concerned for?
HSV
(RBCs = HSV-1)
What is the dx study of choice for encephalitis?
MRI with contrast
MRI with contrast of pt with suspected encephalitis shows temporal lobe changes. Suspected etiology?
HSV
Pt with suspected encephalitis is not improving or no definitive dx has been made based on CSF, culture, or PCR. What should be ordered?
Serology
(IgM Ab testing for WNV/ mumps/ EBV)
What dx study is ordered as a last resort and if etiology is unknown?
Brain bx
What is included in management for encephalitis?
Empiric acyclovir (HSV most important to ID/ tx)
Seizure prophylaxis/ control
Diuretics if increased ICP- Mannitol, Furosemide
What might indicate a worse prognosis/ poor neuro recovery in a pt with encephalitis?
Elevated initial ICP, intractable seizures
What is the suspected location of cerebral abscess if hx of subacute/ chronic OM or mastoiditis?
(type of direct spread)
Inferior temporal lobe/ cerebellum
What is the suspected location of cerebral abscess if hx of frontal/ ethmoid sinusitis or dental infection?
(type of direct spread)
Frontal lobes
What is the primary source of hematogeneous spread causing cerebral abscess?
Bacterial
Suspected etiology of cerebral abscess if immigrant from Mexico?
Parasite
(Cysticercosis, Taenia solium)
Fungal pathogens as the cause of a cerebral abscess is a/w what?
Multiple abscesses, poor outcomes
Pt presents with unilateral, severe HA that is not relieved with OTC pain meds +/- fever and focal neuro deficits. What you concerned for?
Cerebral abscess
What is the imaging study of choice for cerebral abscess?
MRI with contrast
MRI w/ contrast of pt with suspected CNS infection shows a ring-enhancing lesion that is poorly demarcated with localized edema, acute inflammation and no evidence of tissue necrosis. What are you concerned for?
Early cerebral abscess
(1-2 weeks)
MRI w/ contrast of pt with suspected CNS infection shows a ring-enhancing lesion with necrosis and liquefaction, and is surrounded by a fibrotic capsule. What are you concerned for?
Late cerebral abscess
(> 2 weeks)
In pt with suspected cerebral abscess and focal sxs, unilateral CN deficits, or hemiparesis/ papilledema, what study is contraindicated?
LP
What is the management for cerebral abscess?
Neurosurgery involvement (CT-guided aspiration/ surgical excision)
Empiric IV abx (then alter once pathogen established)
What is the tx for cerebral abscess if oral source?
Metro + penG
What is the tx for cerebral abscess if otogenic or sinus source?
Metro + ceftriaxone or cefotaxime
Intracranial epidural abscess (IEA) is typically a complication of what?
Neurosurgery
Pt presents with fever, HA, lethargy, N/V +/- purulent drainage from nose/ ear (secondary to sinusitis) OR +/- increased ICP/ papilledema, focal neuro changes (brain compression). What are you suscpicious for?
IEA
What is the dx study of choice of IEA?
MRI w/ contrast
What is the management for IEA if post- neurosurgery?
Drainage + abx
Neurosurgery involvement
Repeat MRI in 4-6 weeks
What is the management for IEA?
Empirix abx
If contiguous spread: Metro + 3rd gen Cef
All others: Vanco + Metro + 3rd gen Cef
Direct extension of osteomyelitis, direct inoculation into spinal canal (epidural catheter) hematogenous spread of bacteria, damage to spinal cord, or microbes (S. aureus) can all result in what CNS infection?
Spinal epidural abscess (SEA)
Pt presents with fever, spinal pain, neuro deficits +/- back pain, shooting/ “electrical” nerve root pain, motor weakness/ sensory changes/ B+B dysfunction, or paralysis. What are you concerned for?
SEA
What is the most concerning complication a/w SEA?
Irreversible paraplegia
(24- 36 hours)
What is 1st and 2nd line dx imaging of choice for SEA?
1st line- MRI w/ contrast asap
2nd line- CT w/ contrast
What is the management for SEA?
Vanco + 3rd/ 4th gen Cef x 4-8 weeks
Early surgical decompression/ drainage
F/u MRI in 4-6 weeks
