Lecture 4: CNS Infections COPY Flashcards
What are the types of CNS infections?
- Meningitis
- Encephalitis
- Meningoencephalitis
- Brain Abscess
What are the meningeal signs?
- Nuchal rigidity
- Brudzinski’s
- Kernig’s
What physical manifestation is seen in increased ICP in infants?
Bulging fontanelle
What are the S/S of increased ICP?
- Papilledema
- Poorly reactive pupils
- Abducens palsy (horizontal diplopia)
- N/V
- Bulging fontanelle in infants
What layers of the meninges does meningitis typically affect?
- Arachnoid mater
- Pia mater
What are the typical colonization areas for pathogens that cause meningitis?
- Nasopharynx
- Respiratory tract
- Skin
- GI/GU tracts
What are the two ways pathogens spread to the CNS?
- Hematogenous (MC)
- Direct contiguous spread via face sinuses
What is the #1 community acquired bacteria to cause meningitis?
Strep pneumo (MC in adults > 20)
N. meningitiditis causes SEVERE meningitis
What are the most common healthcare acquired bacterial meningitis pathogens and when does it occur?
- Staph aureus and coagulase-negative staph (normal skin flora)
- MC after neurosurgical procedures
What is the MC bacteria that causes meningitis in neonates?
- GBS
- E. coli
What is the MC bacteria that causes meningitis in children > 1 month?
- Strep pneumo
- N. meningitiditis
- H flu (unvaccinated)
What is the classic triad of bacterial meningitis?
- Headache
- Fever
- Nuchal rigidity
- ALOC/AMS (sometimes)
First 3 occur 50% of all cases
2 out of 4 are present in almost all cases
What additional S/S are seen in bacterial meningitis for adults?
- N/V
- Photophobia
- Increased ICP
- Meningococcal rash (petechiae or purpura)
Presence of meningococal rash suggests N. meningitiditis, which is more severe.
How might an infant present in bacterial meningitis?
- Restlessness
- V/D
- Poor feeding
- Respiratory distress
- Seizures
- Jaundice
- Bulging fontanelle
Kernig and brud is NOT reliable in younger children
What are the historical red flags for bacterial meningitis?
- Recent exposure
- Recent illness/abx tx
- Recent travel to endemic areas (sub-saharan africa)
- Penetrating head trauma
- CSF otorrhea or CSF rhinorrhea
- Cochlear implants
- Recent neurosurgery (esp. VP shunts)
What is the absolute #1 treatment for bacterial meningitis?
Starting Empiric ABX
Goal is 60 minutes to starting abx!
What two things are of upmost importance in diagnosing bacterial meningitis?
- Blood cultures x2
- LP
What would prompt us to order a CT scan prior to performing an LP?
- Immunocompromised state
- Increased ICP S/S
- History of CNS disease
TAP AS IF
Trauma
Age > 60
Papilledema
AMS
Seizures
Immunocompromised
Focal Neurologic deficits
What are the landmarks and location for LPs?
- Iliac crest/PSIS
- L2-L3, L3-L4 or L4-L5 intervertebral spaces
What does high flow of CSF from a LP suggest?
Increased ICP
What are the 4 tubes for CSF analysis?
- Cell count and diff
- Glucose and protein
- Gram stain, C&S
- Cell count and diff (repeat) or special studies
On a CSF analysis suggestive of bacteria, what would I see?
- Increased pressure
- Cloudy, purulent appearance
- Many PMNs
- Low glucose
- High Protein
- Elevated lactate (>= 31.53) (additional study)
- Decreased CSF:serum glucose ratio < 0.4 (additional study)
Bacteria eat glucose so glucose is low, and then they poop out protein.
Why do we order a coag panel for meningitis patients?
To know if they require platelets vs FFP post LP
What kind of illness can be negative on CSF fluid?
Tick-borne diseases (Lyme and Ehrlichiosis)
What could MRI show in terms of differentials for meningitis?
- Brain Abscess
- SAH
When is ABX given in terms of LP?
After the LP UNLESS the LP is delayed.
What is step 1 of empiric therapy for bacterial meningitis?
Dexamethasone prior to ABX
Prevents release of inflammatory cytokines.
For a healthy patient that is less than 50 yo, what is the empiric ABX for bacterial meningitis?
- Rocephin
- Vanco
- Acyclovir
Do all 3 until a CSF analysis returns.
Rocephin can be subbed for ceftazidime or meropenem for neurosurg patients.
Roc the van cycle
What is the alternative to rocephin in neonates?
Cefotaxime + ampicillin
Rocephin causes hyperbilirubinemia
amplified taxes
When is ampicillin indicated as additional therapy for bacterial meningitis?
- Cover listeria
- < 1 month old or > 50 yo
- Immunocompromised patients
When is doxycycline indicated as additional therapy for bacterial meningitis?
During tick season
When is metronidazole indicated as additional therapy for bacterial meningitis?
G- anaerobes from sinusitis, otitis, or mastoiditis
What should we do to manage increased ICP?
- Elevation of the patient’s head to 30deg
- Intubation with hyperventilation
- Mannitol (osmotic diuretic to reduce fluid)
What bacteria requires the longest duration of ABX therapy in bacterial meningitis?
Listeria (21 days)
When is repeat CSF analysis indicated in bacterial meningitis?
- No improvement after 48 hrs of appropriate therapy
- Microorganisms resistant
- Persistent fever > 8 days (without any other known cause)
If CSF cultures are positive on repeat, what should we do with our ABX?
Adminster them intrathecally or intraventricularly.
A repeat culture should be sterile ideally.
How does mortality vary in bacterial meningitis?
- Highest < 1 year
- Low in midlife
- Increases in old age
What is the PPE isolation for bacterial meningitis?
Droplet
When do we do prophylaxis for bacterial meningitis and what is the treatment?
- Close exposure to H flu meningitis
- Rifampin 4 days
What is considered contact for H flu meningitis?
Contact for 5/7 days for 4 hours for an index patient.
- Anyone exposed that is < 2yo
- Anyone exposed to someone < 4yo and lives with them
- Anyone exposed not vaccinated against Hib
What is chemoprophylaxis for N. menigitiditis?
2 days of rifampin for any close exposures.
What is the chemoprophylaxis for GBS meningitis?
- Vaginal/anal swab at 35-37 weeks gestation
- PCN to treat
What is the #1 way to prevent meningitis?
- Pneumococcal vaccine
- MenB and MenACWY
- Hib
What is the MCC of viral/aseptic meningitis?
Enteroviruses
What are the risk factors for viral meningitis?
- Infants < 1 mo
- Immunodeficient patients
- Exposure
- Travel to endemic west nile, lyme, or other ticks
- Sexual exposure (HSVs, HIV, syphilis)
How does viral meningitis typically present?
- Less severe version of bacterial
- SHOULD NOT SEE focal neuro deficits
What specific findings are related to certain viruses for viral meningitis?
- Diffuse maculopapular exanthem: entero, HIV, syphilis
- Parotitis/orchitis: mumps in unvaccinated
- Genital/oral lesions: HSV or syphilis
- Thrush: HIV
- Asymmetric flaccid paralysis: West Nile
What additional study should be ordered in viral meningitis suspicion?
PCR tests for every individual virus
Usually start with enterovirus
How does WBC count vary in viral meningitis?
Elevated but not as high as bacterial because it is predominantly lymphocytes.
What lab test may be elevated specifically in mumps?
Amylase (due to parotitis)
What viruses should NOT be tested serologically?
- HSV
- VZV
- CMV
- EBV
Everyone has exposure to these usually.
When is imaging indicated for viral meningitis?
CNS involvement.
Who do we treat empirically for suspected viral meningitis?
- Elderly
- Immunocompromised
- Strong early suspicion of bacterial meningitis (err on the side of caution)
If we have a patient that we suspect viral meningitis but their CSF is indeterminate after analysis, what can we do?
- Administer empiric ABX after getting cultures
- Observe for 24 hrs without giving ABX and repeat CSF in 6 hours.
either or
What are the two viruses that require acyclovir for viral meningitis?
- HSV
- VZV
Newborns require the longest duration of antivirals
What vaccines help prevent viral meningitis?
- IPV
- MMR
- Varicella Zoster
What is the MC etiology for encephalitis?
Viral (HSV, VZV, EBV)
What environmental factor might suggest amebic encephalitis?
Warm, freshwater area
What environmental factor might suggest toxoplasmosis induced encephalitis?
Cat litter
What is the primary difference between encephalitis and meningitis?
Encephalitis has more neurologic symptoms, but varies depending on the area inflammed.
What S/S suggest poor perfusion?
- Slow cap refill
- Cool extremities
- Decreased urine output
- Decreased level of alertness
What findings would suggest a neonate has a HSV infection?
- Herpetic lesions (face)
- Keratoconjunctivitis
- Oropharyngeal lesions
What is the primary diagnostic test for encephalitis?
CSF PCR tests for individual viruses
CSF analysis should be same as viral meningitis.
What MRI findings suggest HSV etiology?
Focal findings on CT/MRI
90% of HSV encephalitis have focal findings.
What do EEG abnormalities suggest for encephalitis etiology?
HSV
When is a brain biopsy indicated?
All of the 3:
- Focal abnormality on MRI
- Negative CSF/PCR
- Deterioration despite acyclovir and standard therapy.
What CSF finding is characteristic of amebic infection?
Motile trophozoites seen in wet mount of fresh, warm CSF.
What is the primary anticonvulsant for encephalitis?
Lorazepam
For acute treatment
What is secondary prevention of seizures in encephalitis accomplished with?
Phenytoin or Fosphenytoin
Prevention only.
What are the neuro checks?
- LOC
- A/O
- pupil check
- facial symmetry
- tongue midline
- speech clarity
- sensation
- grasp strength
- strength and ROM of UE and LE
What is empiric antiviral therapy for encephalitis?
IV acyclovir for 21 days
Within 30 minutes
When is definitive antiviral therapy indicated for encephalitis?
- HSV
- Severe VZV/EBV
When should CSF be repeated for encephalitis?
- Repeat if they were PCR +.
- If repeat is positive, then remain on therapy
What is a brain abscess?
Uncommon, focal, suppurative infection within brain parenchyma and surrounded by a capsule.
Non-encapsulated is cerebritis
What are the common etiologies for brain abscess?
- Direct spread (otitis media and mastoiditis are MC)
- Hematogenous (25%)
- Trauma/Surgery (30%)
What is the MC symptom in brain abscess?
Gradual HA
What are the 3 common abscess locations that produce focal neurological deficits?
- Frontal lobe: Hemiparesis
- Temporal lobe: Aphasia/dysphasia
- Cerebellar: nystagmus/ataxia
What are the common S/S of a brain abscess?
- HA
- Focal neurologic deficits
- Fever
- New onset seizure
- S/S of increased ICP
What imaging is used to workup a brain abscess?
CT or MRI WITH contrast
How are ABX and aspiration of brain abscess given?
CT/MRI guided stereotactic needle aspiration
Lack of what sign may suggest brain tumor over brain abscess?
Fever
More likely to be a solid mass
What is the empiric treatment for community acquired brain abscess?
- Rocephin + metronidazole
- Drain abscess
What is the empiric treatment for head trauma or neurosurgery related brain abscess?
- Ceftazidime + Vanco
- Meropenem + Vanco
- Drain abscess
When are steroids indicated for brain abscess?
Significant peri-abscess edema with associated mass effect and increased ICP
Steroids prevent encapsulation.
What are the indications to NOT drain a brain abscess?
- Inaccessible abscess
- Small < 3cm or non-encapsulated
- Unstable condition
When is it indicated to completely excise an abscess?
Multiloculated or aspiration
What is the overall treatment for a brain abscess?
- Prophylaxis for seizures
- Empiric parenteral ABX therapy
- Drain abscess
What is the clinical course of a brain abscess?
- 6-8 weeks of ABX
- Serial MRI or CT monthly or bimonthly
- Prophylactic anticonvulsant for 3 months minimum (until EEG is normal)
What suggests poor prognosis for brain abscess?
- Rapid progression of infection prior to admission
- Severe mental status changes on admission
- Stupor or coma (Extremely bad)
- Rupture into ventricle (Extremely bad)
How common are sequelae in brain abscess survivors?
20% of survivors
