CNS Infections Flashcards
inflammatory disease of the meninges surrounding the brain and spinal cord
what disorder?
meningitis
Bacterial, Viral or Fungal
inflammation of both the brain and the meninges
what disorder?
Meningo-encephalitis
acute inflammation of the brain itself/brain parenchyma
what disorder?
encephalitis
Bacterial, Viral, (Parasitic, Fungi, Spirochetes)
a collection of purulent material within the brain tissue resulting from inflammation of a nearby or remote source
what disorder
Brain Abscess
general s/s of CNS infections
- Fever
- HA
- Altered mental status
- confusion, memory loss, loss of alertness, disorientation, defects in judgment or thought, unusual or strange behavior, poor regulation of emotions, and disruptions in perception, psychomotor skills, and behavior - Meningeal signs
- nuchal rigidity, (+) Kernig/Brudzinski - Increased intracranial pressure (ICP)
- Papilledema, poorly reactive pupils
- Abducens (6th CN) palsy - horizontal diplopia
- N/V
- Bulging fontanelle (soft spot) in infants
which meninges layer is the outermost layer - strong fibrous membrane
dura mater
which meninges layer is middle layer with cobweb like filaments that attach to the innermost layer
Arachnoid Mater
which meninges layer is the space between arachnoid and pia mater - filled with CSF and contains blood vessels
Subarachnoid Space
which meninges layer is the innermost layer - a very thin and delicate membrane that is tightly to bound the surface of the brain
Pia Mater
an acute purulent infection of the arachnoid mater and the subarachnoid space
Bacterial Meningitis
pathophys of Bacterial Meningitis
MC from previously colonized distant infection
- Nasopharynx, rsp tract, skin, GI tract and GU tract
- Access to CNS by 2 processes:
- hematogenous spread - MC
- direct contiguous spread
— sinusitis, otitis media, mastoiditis, trauma, neurosurgical procedures
Newborns
- pathogens colonized from the maternal intestinal or genital tract
- transmitted from nursery personnel or caregivers at home
pathogenetic causes of bacterial meningitis in adults?
Community acquired
-
Strep pneumo (MC)
- MC cause in adults >20 yrs old - Group B Strep (GBS) (~15-20%)
- N meningitidis (~10-20%)
- H flu type B
- Listeria monocytogenes (< 5%)
Healthcare acquired
- S. aureus and coagulase-negative staphylococci (normal skin flora)
- MC after neurosurgical procedures
pathogenetic causes of bacterial meningitis pediatrics
- Neonatal
- GBS
- E coli
- G-bacilli - Children > 1 month
- Strep pneumo
- N meningitidis
- H flu type B (Hib)
— MC in unvaccinated
- GBS
- G- bacilli
presentation of adult bacterial meningitis
- HA - MC
- F - 2nd MC
- Nuchal rigidity/meningeal signs
- Decreased LOC/altered mental status
- N/V
- photophobia
- seizure
- increased ICP
- papilledema, CN palsy III, IV, VI, VII
- N/V, change in LOC, confusion -
meningococcal rash
- maculopapular rash that become petechial and/or purpuric involving the trunk, LE, mucosal membranes, conjunctiva
- seen in septic meningitis with N. Meningitidis
triad - HA, F, meningeal signs - present <50% of cases
where to look for primary source of infection in adult bacterial meningitis
sinus
ears
mastoid
evidence of semi-recent trauma/surgery
presentation of Bacterial Meningitis - Pediatrics
- Fever or hypothermia
- Lethargy
- Restlessness/irritability
- Poor feeding/ decreased appetite
- Vomiting/diarrhea
- Respiratory distress
- Seizures
- Jaundice
- Bulging fontanel (infants)
S/S in older children
- Confusion
- HA
- Photophobia
- Meningeal signs - Kernig, Brudzinski
Hx red flags for bacterial meningitis
- Recent exposure to similar illness
- Recent illness or antibiotic treatment
- Ex: pneumonia, sinusitis, otitis, mastoiditis, endocarditis - Recent travel to areas with endemic disease
- Meningococcal disease (sub-Saharan Africa/India) - Penetrating head trauma
- CSF otorrhea or CSF rhinorrhea
-Hx of skull fracture - Cochlear implant devices
- Recent neurosurgical procedures
- most often a ventriculoperitoneal (VP) shunt
Most important Work-Up and Management for bacterial meningitis
- Immediate collection of blood cx x 2
- gram stain, cx & sensitivity (C&S) - Prompt LP w/ CSF evaluation
DO NOT delay empiric Abx therapy for LP or CT
Would still get CBC, chemistry panel, etc
Infectious Diseases Society of America (IDSA) guidelines recommend CT scan before LP if: (6)
- Immunocompromised
- Hx of CNS dz - mass lesion, stroke, or focal infection
- New seizure (w/n 1 wk of presentation)
- Papilledema
- Abnml LOC
- Focal deficits
what are the 4 tubes in a CSF analysis?
Tube 1 - Cell count and diff
Tube 2 - Glucose and protein levels
Tube 3 - Gram stain, C&S
Tube 4 - Cell count and diff (if repeat is needed) or special additional studies (depending on initial CSF analysis)
- Pressure - 80-200 mmH2O
- Appearance - Clear, water-like
- WBC Count - 0-5 (lymphocytes) cells/µL
- Glucose - 50-75 mg/dL
- Protein - 14-40 mg/dL
- Additional Studies
- CSF : serum glucose ratio > 0.6 - Microbiology - Negative findings on workup
how would you analyze this CSF?
normal
- Pressure - 200-300 mmH2O
- Appearance - Cloudy, purulent
- WBC Count - 100-5000 (l>80% PMNs) cells/µL
- Glucose - <40 mg/dL
- Protein - >100 mg/dL
- Additional Studies
- Lactate ≥ 31.53 mg/dL
- CSF : serum glucose ratio <0.4 - Microbiology - (+) 60% of Gram stains and 80% of cx
how would you analyze this CSF?
bacterial meningitis
- Pressure - 90-200 mmH2O
- Appearance - clear
- WBC Count - 100-300 (lymphocytes) cells/µL
- Glucose - normal or slightly low
- Protein - normal or slightly high
- Microbiology - isolation, PCR assys
how would you analyze this CSF?
viral meningitis
Additional labs for Bacterial Meningitis
- CBC - PMN leukocytosis (left shift)
- CMP
- glucose - compare with CSF glucose
- liver and kidney function for abx dosing adjustments - Coag profile (INR, APTT, platelets and fibrinogen)
- helps to differentiate who may need platelet or FFP after LP
additional imaging for bacterial meningitis
- Non urgent CT/MRI to rule out differential diagnoses
- MRI is preferred due to is superiority in demonstrating cerebral edema but not readily available
begin abx therapy for bacterial meningitis within ? of patient arrival
60 minutes
Administered immediately after LP
DO NOT delay abx therapy if LP is delayed
therapy for bacterial meningitis
empiric
-
ALL PTs
- dexamethasone
- Given 0-20 min. prior to 1st dose abx and continued x 4 d -
Healthy 1m - 50 yr
- ceftriaxone (any 3rd/4th-gen) PLUS
— Alt: cefotaxime or cefepime
- vancomycin PLUS
- acyclovir + ampicillin/doxy/metronidzaole
— HSV encephalitis is a top DDx -
Infants < 1 mo
- cefotaxime + ampicillin - general management
Substitute ceftriaxone with what other meds in neurosurgical or neutropenic pts to cover P. aeruginosa in bacterial meningitis?
ceftazidime or meropenem
ceftriaxone is CI in neonates due to?
risk of hyperbilirubinemia
you would choose ampicillin as the individualized care for bacterial meningitis for ?
- <1 month and >50 years old
- immunocompromised
- chronic illness, organ transplant, pregnancy, malignancy, immunosuppressive therapy - covers L. monocytogenes
you would choose doxy as the individualized care for bacterial meningitis for ?
tick season to cover tick-borne bacterial infections
you would choose metronidazole as the individualized care for bacterial meningitis for ?
covers gram-negative anaerobes coinciding otitis, sinusitis or mastoiditis
general management for bacterial meningitis
-
Supportive care
- monitor VS and treat as appropriate
- IV fluids
- control fever, pain -
Control of ICP
- elevation head 30–45°
- intubation with hyperventilation
- mannitol - Adjust abx after G stain (24-48 h) and C&S have returned (48-72 h)
Antibiotic therapy duration for bacterial meningitis (each causative agent)
N. Meningitidis - 7 days
H. Influenzae Type B - 7 days
S. Pneumoniae - 10-14 days
S. Aureus - at least 14 days
L.monocytogenes - 21 days
indications for repeat CSF analysis
- No improvement w/n 48 h after the initiation of appropriate therapy
- Microorganisms resistant to standard abx
- 2-3 days after the initiation of therapy - Persistent fever > 8 d (without other known cause)
Repeat CSF cultures should be sterile
If cultures remain positive despite appropriate therapy after repeat CSF cx, consider to do what?
Bacterial Meningitis
intrathecal (or intraventricular) abx administration
Mortality in bacterial meningitis is highest when?
decreases in ___, and increases again in _____
increase - in the first year of life
midlife, old age
Common neurologic sequelae after bacterial meningitis - temporary or permanent
decreased intellectual function
memory impairment
seizures
hearing loss and dizziness
gait disturbances
prevention/precautions with bacterial meningitis?
-
Droplet precaution
- all pts until etiology is determined
- continue for 24 h after start of abx in N. meningitidis - Chemoprophylaxis
- close exposure to meningitis w/ H flu - rifampin x 4 d
- close exposure to N. meningitidis - rifampin x 2 d
- GBS - prophylactic IV PCN during delivery
- Neurosurgery
indications for chemoprophylaxis (H. flu) for bacterial meningitis?
- Contact for ≥4 h for at least 5 out of the 7 d before admission of index pt
- Anyone exposed under the age of 2 years
- Anyone exposed who lives in a home with a child < 4 y/o
- Anyone exposed who is not fully immunized against Hib
indications for chemoprophylaxis (H. flu) for bacterial meningitis?
prolonged (>8h) exposure in close proximity (<3 ft)
direct exposure to oral secretions
Exposure 7 days before onset of sx up through 24 hrs after initiation of abx
alt tx for chemoprophylaxis for N. meningitidis - Bacterial Meningitis
- ciprofloxacin 500 mg PO
- ceftriaxone 250 mg IM once
- Vaginal/anal swab testing for group B strep when for chemoprophylaxis of bacterial meningitis?
- TX if positive?
between 35-37 wks gestation
prophylactic IV PCN to be administered during vaginal delivery if (+)
Perioperative antimicrobial prophylaxis for bacterial meningitis is indicated for who?
patients undergoing any form of neurosurgery
The most effective way to prevent meningitis is ?
vaccination
Streptococcus pneumoniae (PVC13, PPSV23)
Neisseria meningitidis (MenB and MenACWY)
Haemophilus influenzae Type B (Hib)
a condition that presents with evidence of meningeal inflammation (H&P & CSF profile) with a negative bacterial culture
Viral (Aseptic) Meningitis
MC cause of Viral (Aseptic) Meningitis
enteroviruses - coxsackieviruses, echoviruses, human enteroviruses
risk factors for viral meningitis
- Infants <1 Month old
- Most cases children < 5 y/o - Immunodeficient patients- at risk for more severe infection
- Exposure to someone with viral meningitis
Historical Features for viral meningitis
- Comprehensive travel and exposure hx
- concentrate on areas of endemic West Nile virus, Lyme disease, other tick borne disease - Ill contacts with similar sx or viruses
- Vaccination hx
- Sexual exposure - HSV-1/2, HIV, syphilis
presentation of viral meningitis
similar to bacterial meningitis - often less severe
- HA
- Photophobia and/or pain with EOM
- Nuchal rigidity
- Constitutional sx - malaise, myalgia, anorexia, N/V/D, abdominal pain
- Mildly diminished LOC - drowsiness or mild lethargy
- if there is a marked decrease in LOC consider other diagnosis
profound alterations in LOC, seizures and focal neuro deficits are not seen
what are the specific findings of viral meningitis
- Diffuse maculopapular exanthem - enteroviral infection, primary HIV or syphilis
- Parotitis/Orchitis - mumps
- Genital/Oral Lesions - HSV
- Thrush - HIV
- Asymmetric flaccid paralysis - West Nile
work-up (labs) for viral meningitis
LP - same approach as bacterial meningitis
- opening pressure with CSF analysis (same as bacterial)
- WBC - lymphocyte predominant
- Gram’s stain of CSF will be negative for any growth - CSF PCR amplification of viral nucleic acid
- PCR - CSF PCR for each individual virus
— highly sensitive and specific but never 100% correct - always use clinical judgement
CBC, CMP, coags - non-revealing in viral
Amylase - elevated in mumps
Blood, feces, and throat swabs for viral etiology - viral shedding in the stool can persist for weeks and therefore isn’t a reliable tool
Viral serology (IgM)
- useful for causes that are not commonly seropositive
- Serum titers of antibodies against HIV
Do not use viral serology in viral meningitis for what viruses?
HSV, VZV, CMV, and EBV
frequently seropositive
imaging for viral meningitis
Neuroimaging
- CT/MRI is not necessary in uncomplicated
- Indications include:
- altered LOC
- seizures
- focal neurologic s/s
- atypical CSF profiles
- underlying immunocompromising treatments or conditions
management for viral meningitis
- Empiric abx/antivirals for:
- elderly
- immunocompromised
- strong early suspicion of bacterial meningitis -
IF dx INDETERMINATE after CSF eval
- empiric abx after blood and CSF cx OR
- observe (w/o abx) and repeat LP in 6-24 h - d/c Empiric if pt is improving and (-) cx
- Most self limited and tx is supportive
-
based upon etiology:
- HSV - IV acyclovir (dose based upon weight)
— Newborn - 3 mo - 21 d
— +3 mo - 10-21 d
- VZV (severe) - IV acyclovir - 10-14 d
- HIV- consult ID
course and prognosis Viral Meningitis
MC self limited course - 7-10 days without specific therapy
Can be fatal or associated with significant morbidity in neonates
prevention of viral meningitis
Vaccination
poliovirus (IPV)
mumps, measles, rubella (MMR)
varicella (VAR/Zoster)
what is meningoencephalitis?
Encephalitis with meninges involved
what is encephalomyelitis/encephalomyeloradiculitis
Encephalitis when spinal cord/nerve root involved
cause of encephalitis
MC viral
- MC - herpesviruses (HSV, VZV, EBV)
- Other: enteroviruses, measles, mumps, rubella, rabies virus, human herpesvirus 6¹, arthropod-borne viruses
- Other - less common
- autoimmune encephalitis - autoimmune antibodies found in serum or CSF
- amebic encephalitis - motile trophozoites seen in wet mount of warm, fresh CSF
- parasitic - toxoplasmosis
presentation of Encephalitis
- Fever
- HA, N/V
- Seizures
- Altered LOC - mild lethargy to coma
- Psychotic sx - hallucination, agitation, personality/behavioral changes
- Focal neurologic signs - Speech/hearing problems, CN deficits, involuntary movements (e.g. tremor, myoclonic jerks), muscle weakness, partial paralysis in UE/LE, memory loss
- Occasional involvement of HPA axis may result in:
- temp dysregulation (hypothermia)
- Diabetes Insipidus
- SIADH - Neonatal (0-28 d)/young infant
- fever
- poor feeding
- irritability
- seizure
- decreased perfusion - slow cap refill, cool extremities, decreased urine output, decrease level of alertness - Findings indicative of:
- HSV infections in neonates - herpetic lesions, keratoconjunctivitis, oropharyngeal lesions
- meningitis = signs of meningeal irritation
work-up/labs for encephalitis
- LP w/ CSF analysis - same as bacterial meningitis
- results same as viral meningitis -
CSF PCR amplification - primary diagnostic test
- CSF PCR for each individual virus has to be ordered
- work-up/imaging for encephalitis?
- results?
- MRI/CT brain and EEG
- MRI sensitive > CT
- “Focal” findings = HSV
- HSV encephalitis = EEG abnormalities - Brain bx
indications for brain bx for encephalitis
- focal abnormality on MRI
- negative CSF analysis/PCR
- progressively deteriorate despite tx with acyclovir and supportives
additional labs for encephalitis
- CBC - often unremarkable
- CMP
- lyte abnormalities if dehydration or SIADH
- glucose - compare to CSF glucose and r/o hypoglycemic presentation
- BUN/Cr - assess hydration status, end-organ damage and renal function for med dosing adjustments
- LFT - assess for end-organ damage, med adjustment - PT/PTT - assess bleeding disorders/complications, helps determine the need for transfusion of FFP or platelets
- Blood cx
- Viral cx and Tzanck smear - herpetic lesions
you get an MRI/CT for suspected encephalitis but results show a space occupying lesion, what is this dx now?
brain tumor/abscess
how can you assess for autoimmune encephalitis?
assess specific autoantibodies in serum/CSF
what factors would make you feel more suspicious of amebic infection instead of encephalitis?
- Hx of exposure to warm, iron-rich pools of water, including those found in drains, canals, and both natural and human-made outdoor pools
- CSF analysis resembles bacterial meningitis
- motile trophozoites are seen in wet mount of fresh warm CSF
an immunocompromised pt that has a cat is suspected to have encephalitis, but what else could be in your ddx?
Toxoplasmic/cryptococcal neuroinfection
tx for Encephalitis
- Continuous monitoring and tx abnormal VS - rsp support, fluids
-
Seizures - IV lorazepam
- secondary prevention - phenytoin or/fosphenytoin -
Increased ICP - neuro checks
- look for deterioration or change in neuro status
- elevate head of bed, control F and pain, control of straining and coughing, prevent seizures and significant hypo/HTN - Empiric : IV acyclovir x 21 d
- Adults/Pediatric
- for all pts as a ddx
— Only HSV and severe VZV/EBV encephalitis get definitive antiviral therapy
- Lab specimens and blood cx obtained prior to first antiviral dose - Empiric abx if bacterial meningitis is in the ddx
what are neuro checks?
- Assess level of consciousness
- full consciousness, lethargy, obtundation, stupor, coma - Perform an A/O and compare with the patients baseline
- Perform a pupil check
- Assess facial symmetry
- Perform tongue midline
- Assess patient’s speech clarity for slurs, impediments or incoherence
- Assess sensation - observe physical response, sensitivity to touch and check for numbness or lack of movement
- Assess grasp strength
- Assess strength and ROM of UE and LE
First dose of empiric antiviral tx should be administered to pts with potential viral encephal within how long of arrival to ED?
30 minutes
what should be repeated at the completion of antiviral therapy in those patients who were PCR (+)?
CSF analysis for PCR
If remains positive additional antiviral therapy should be given
Complications to watch for and attempt to prevent in Encephalitis:
- aspiration pneumonia, stasis ulcers/decubitus, contractures, DVT/PE, infections of indwelling lines/catheters
- Sequelae:
Seizure disorder
Cognitive impairment
Movement disorders
tremor, myoclonus, parkinsonism
Hemiplegia
difference between encephalitis vs meningitis?
Presence or absence of normal brain function is the most important distinguishing feature between the two
- Meningitis - uncomfortable, lethargic or distracted by HA but CEREBRAL FUNCTION is generally intact
- Encephalitis- HAS abnormalities in brain function:
- Altered mental status
- Motor and sensory deficits
- Altered behaviour and personality changes
- Speech and movement disorders
Patient Education to Avoid Transmission of All CNS Infections
- Avoid sharing food, utensils, drinks and other objects with person exposed to or has infection
- Wash hands with soap and water
- Keep vaccinations UTD
- H. flu, Pneumococcal, N Meningitidis - Prophylactic tx of those exposed
- Reduce exposure to infected arthropods
an uncommon focal, suppurative infection within the brain parenchyma and surrounded by a capsule
Brain Abscess
a non-encapsulated abscess is referred to as ?
cerebritis
risk factors/causes of brain absceses?
- Direct spread
- otitis media, mastoiditis (33%)
- paranasal sinusitis (10%)
- dental infections (2%) - Hematogenous spread (25%)
- pyogenic infections (anywhere in the body) - Trauma/Surgery (30%)
- penetrating head trauma
- neurosurgical procedures
In 25% of patients no obvious cause is identified
presentation of brain abscess?
-
HA - MC sx (>75%)
- onset: gradual, 10 d after onset of sx - Focal neurologic deficits (>60%)
- hemiparesis
- aphasia/dysphasia
- nystagmus/ataxia - Fever (50%)
- New onset seizure (15-35% of patients)
- S/S of increased ICP
- papilledema, N/V, change in LOC, confusion
pt with suspected brain abscess is having hemiparesis, which part of the brain is involved?
frontal lobe abscess
pt with suspected brain abscess is having aphasia/dysphasia, which part of the brain is involved?
temporal lobe abscess
pt with suspected brain abscess is having nystagmus/ataxia, which part of the brain is involved?
cerebellar abscess
work up for brain abscess?
Dx is made by imaging studies
- MRI or CT w/ contrast
- MRI more sensitive > CT BUT not as readily available - Routine serology
- CBC - elevated WBC
- CMP - assessing renal and liver function
- Blood cx x 2 - preferably before first abx dose - CT/MRI-guided stereotactic needle aspiration
- C&S of abscess aspirate to guide therapy
upon CT w/ contrast shows a focal area of hypodensity surrounded by ring enhancement with surrounding edema
what this be
brain abscess
upon a MRI w/ contrast shows a capsule that enhances surrounding a hypodense center and surrounded by a hypodense area of edema
what this be
brain abscess
ddx if there is a fever present with brain abscess?
subdural empyema, bacterial/viral meningitis/encephalitis, superior sagittal sinus thrombosis
r/o after imaging is obtained
ddx if no fever present with brain abscess?
primary/metastatic brain tumor
imaging can differentiate abscess vs solid tumor
tx for brain abscess
- High dose empiric parenteral abx AND neurosurgical drainage
- Community - ceftriaxone + metronidazole
- hx of head trauma or recent neurosurgery - ceftazidime + vanc OR
meropenem + vanc - Steroids ONLY if there is peri-abscess edema w/ associated mass effect and increased ICP
- seizure prophylaxis
- abscess drainage if indicated
- Complete excision ONLY IF recommended
Abscess drainage is recommended for all pts with brain abscesses EXCEPT:
- abscess is neurosurgically inaccessible
- small (<2–3 cm) or non-encapsulated abscesses
- unstable
complete excision of brain abscess if recommended ONLY if?
abscess is multiloculated or aspiration fails
management/clinical course of brain abscess?
- Minimum of 6–8 wks of parenteral abx
- Serial MRI/CT monthly or twice-monthly basis
- Prophylactic anticonvulsant x 3 mo
- can be d/c once EEG is normal both pre- and post medication withdrawal
poor prognostic signs for brain abscesses
- Rapid progression of the infection before hospitalization
- Severe mental status changes on admission
- Stupor or coma (60-100% mortality)
- Rupture into ventricle (80-100% mortality)
Sequelae occur in ≥20% of survivors
seizures, persisting weakness, aphasia, or mental impairment
