CNS Infections Flashcards
Most common causes of meningitis
- Bacterial (acute bacterial meningitis)
- Viral (aseptic meningitis)
Most common pathogens of ABM
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haeomphilus influenza type B
- Group B Streptococcus
- Listeria monocytogenes
Most common causes of viral meningitis
- ENTEROVIRUS**
- HSV
- Lymphocytic choriomeningitis virus
- VZV
Aseptic bacterial pathogens that cause meningitis
- M. tuberculosis
- Lyme*
- Trepenoma
- Ehrlichia
Drug-induced causes of non-infectious meningitis
- Bactrim
- Ciprofloxacin
- Flagyl
- Amoxicillin, penicillin
- Keflex
- NSAIDs
- Ranitidine
- Carbamazepine
2 broad categories of non-infectious causes of meningitis
- Drug-induced
- Systemic
Cardinal sx’s of ABM (4)
- Fever**
- Headache
- Nuchal rigidity
- Altered mental status
2/4 found in almost all ABM cases
What special PE tests would support ABM dx?
Positive Brudzinski and Kernig’s signs
33% ABM pts present with dysfunction in these CNs
III
VI
VII
VIII
How does aseptic meningitis differ from ABM?
More benign course, self-limited → symptomatic support
Risk factors for meningitis
- Age >50
- URI, otitis media, sinusitis, mastoiditis
- Head trauma, neurosurgery
- Crowded living conditions
- Immunocompromised
- Antivacciners
Labs for ABM
- WBCs
- Glucose
- Protein
- WBC’s elevated w/ neutrophilic shift
- Decreased glucose
- Elevated protein
Labs for viral meningitis
- WBCs
- Glucose
- Protein
- WBC’s elevated, lymphocytic
- Glucose normal
- Protein elevated
Labs for fungal meningitis
- WBCs
- Glucose
- Protein
- WBCs elevated, lymphocytic
- Glucose normal to decreased
- Protein elevated
Labs for tuberculosis meningitis
- WBCs
- Glucose
- Protein
- WBCs elevated, lymphocytic
- Glucose decreased
- Protein elevated
Lactate _____ is associated with mortality in meningitis
> 4
When should blood cx be obtained for meningitis?
BEFORE abx
Definitive test for diagnosing meningitis
Lumbar puncture
CSF findings in LP for meningitis
- Elevated opening pressure (>20mmHg)
- WBC >500 more likely bacterial source, but some do have lymphocytic shift early on
When should head CT be performed when diagnosing meningitis?
Before LP, if concerned for increased ICP
Indications for obtaining head CT before performing LP for meningitis
- Abnormal mental status
- Seizure within 1 week of presentation
- Known CNS disease/lesion
- Focal neuro findings
- Papilledema
- Age >60
When should abx be given to treat meningitis?
BEFORE LP/CT if high suspicion for ABM (still got some time before the CSF becomes affected)
How long do you have to obtain LP after giving abx in suspected ABM?
Within 2-4 hours
Tx meningitis
- Abx (based on age, predisposing condition) if ABM suspicion
- Dexamethasone prior to or with abx**
- Antivirals if suspicious for viral etiology
How should you treat elevated ICP?
Mannitol, mild hyperventilation, neurosurgery consult. Consider hypertonic saline
What should you use to tx ABM in age 16-50?
Vanco + 3rd gen. ceph (e.g. ceftriaxone)
What should you use to tx ABM in age >50?
Vanco + 3rd gen. ceph. + ampicillin
What organisms would you suspect in ABM for age 16-50?
- N. meningitidis
- S. pneumoniae
- H. influenzae
What organisms would you suspect in ABM for age >50?
- N. meningitidis
- S. pneumoniae
- Listeria
- Aerobic G- bacilli
What should you use to tx ABM in immunocompromised pts?
Vanco + 3rd gen ceph. + ampicllin
What organisms would you suspect in ABM for immunocompromised?
- N. meningitidis
- S. pneumoniae
- Listeria
- Aerobic G- bacilli
What should you use to tx ABM in pts w/ neurosurgery or recent head/cerebrospinal trauma?
Vanco + 3rd gen ceph. + anti-pseudomonal
OR
Vanco + meropenem
Management for likely viral meningitis
- Admit and treat w/ IV abx while awaiting CSF cx (24 hrs)
- If confident and pt comfortable/reliable can discontinue with 24-48hr follow up +/- single dose abx
Most common etiologies of encephalitis
- Direct viral invasion
- Delayed hypersensitivity reaction to virus or other foreign protein several weeks s/p exposure
Most common viruses that cause encephalitis via direct viral invasion
- Enterovirus
- HSV
Most common viral cause of encephalitis worldwide
Measles
How would you diagnose encephalitis secondary to hypersensitivity reaction?
CSF has no viral proteins
Presentation of encephalitis
- Altered mental status**
- Fever
- Headache
- HPI of mild flu or febrile viral illness w/ possible evidence of meningeal involvement
Risk factors for encephalitis
- Age (young/old)
- Immunocompromised
- Geographic location
- Travel
- Outdoor activity
- Season
- Immunization
Dx encephalitis
Clear, cloudy, turbid, bloody CSF
- Opening pressure >20mmHg
- Slightly elevated protein
- Pleocytosis w/ lymphocytic predominance
- Normal glucose
- Negative gram stain, culture
- PCR*
Findings of HSV on head neuroimaging
Focal edema in orbitofrontal and temporal areas
Findings of WNV, EEE on head neuroimaging
Demyelination in basal ganglia and thalamic areas
Tx encephalitis
- Acyclovir (even before CSF results if suspected)
- Supportive tx → suppress fever, ICP monitoring, fluid restrict, SIADH/hypoNa+
- Benzos/anticonvulsants ppx for seizure
- If elevated ICP → mannitol or hypertonic saline, neurosurgery consult
Arbovirus method of transmission
Through vector (e.g. mosquito)
Where is West Nile Virus found?
All states in summer, early fall
Greatest risk for WNV is _____
Elderly
Most cases of WNV are mild and clinically unapparent with ____ days of sxs and ____ days of incubation
3-6 days sx
3-14 days incubation
Dx WNV
CSF or serum for WNV IgM 3-5 days s/p exposure → positive up to 3 months
May have to repeat if 1st sample negative
Epidemiology of fatal LaCross encephalitis
Age <16
Epidemiology of Eastern Equine encephalitis
Eastern/Central states (none in MA, VT)
Epidemiology of Japanese encephalitis
Travelers (ppx vaccine available)
How is rabies transmitted?
Infected vector to humans by saliva or brain/nervous tissue to mucous membranes, eyes, nose, mouth, open wound
Incubation period for rabies
2-8 weeks before sx’s develop
Tx rabies exposure
Post-exposure ppx even in cases w/out direct contact
- Passive → rabies IG injection x1 around wound
- Active → HDCV IM days 0,3,7,14
No treatment if rabies develops → ~100% fatal
What animals might you specifically be concerned of contracting rabies from?
- Raccoon
- Fox
- Coyote
- Skunk
- Brown bats
Are small rodents able to transfer rabies to humans?
No
What should you do if you suspect a domestic animal has rabies?
10-day observation/quarantine → rabid demeanor reveals itself within this time
Should you be concerned your pet has rabies?
Not really… vaccines are pretty good here (not so much in other countries)
Tx paraneoplastic or autoimmune encephalitis
- IVIG
- Methylprednisolone
- Early tumor resection if applicable
90% epidural abscesses occur where? Why?
Spinal, esp. thoracolumbar region - dura is adherent to skull
Etiology of intracranial epidural abscess
- Sinusitis
- Orbital cellulitis
- Skull fracture
- Neurosurgery
Presentation of intracranial epidural abscess
- Fever
- Headache
- Malaise
- Lethargy
- N/V
Risk factors for epidural abscess
- DM
- ETOH
- Trauma/surgery
- IVDA
- CKD
- Immunosuppression
- Anesthesia/injections
- Pregnancy
Tx intracranial epidural abscess
- Craniotomy to dran abscess
- Vanco + 3rd/4th ceph +/- Flagyl
Common locations of spinal epidural abscess
Thoracic > Lumbar > Cervical
Etiologies of spinal epidural abscess
- Hematogenous spread**
- Direct extension
4 stages of spinal epidural abscess manifestations
- Fever + local back pain
- Radiculopathy d/t nerve root compression
- Spinal cord compression → cauda equina, motor/sensory deficits, saddle anesthesia, ecr. DTRs
- Paralysis
LP should be performed in spinal epidural abscess. T/F
No!
Diagnostic of choice for spinal epidural abscess
MRI (or CT)
NO LP
Tx spinal epidural abcess
- Consult neurosurgery, spine surgery, ID → early surgical decompression/drainage w/ laminectomy within 24 hrs
- May attempt CT-guided drainage if neuro deficits
- Vanco + 3rd/4th ceph. +/- Flagyl → taylor to cx results
