Symptoms of meningitis
Classic Triad: Only ~45% of patients have the complete classic triad of fever, headache, and neck stiffness (nuchal rigidity/meningismus), but nearly 100% of patients have at least 2 of 4 symptoms (fever, headache, nuchal rigidity, altered mental status).
Parthenogenesis of bacterial meningitis
Bacteria reaches the subarachnoid space from the bloodstream (most common), adjacent intracranial infection (sinusitis, mastoiditis, otitis), congenital, traumatic or surgical defects in skull/spinal column
Bacterial cell wall components stimulate pro-inflammatory cytokines (e.g. TNF, IL-1), increase BBB permeability, and recruit neutrophils (PMNs). PMNs add to purulent exudates, and enhance cytotoxic edema via reactive oxygen species
Diagnosis of bacterial meningitis
- Lumbar Puncture
- Blood cultures
- Neuroimaging
Indications to wait to do a LP in a suspected case of bacterial meningitis
- decreased level of consciousness
- focal neurologic deficits
- papilloedema
- new onset seizures
- History of CNS disease or an associated condition (e.g. frontal sinusitis) that increases probability of brain abscess/empyema.
- Immunocompromised
- If above criteria are absent >97% have a normal CT.
Most common organism in bacterial meningitis in neonates
Group B Strep
Most common organism in bacterial meningitis in ages 2-23 months
S. Pneumo
Most common organism in bacterial meningitis in ages 2-35 years old
Neisseria meningitidis
and
S. Pneumo
Most common organism in bacterial meningitis in pts older than 35 years old
S. Pneumo
What organism causes meningitis in 25% of cases involving pts over the age of 60 or immunocompromised?
Listeria monocytogenes
CSF profile in bacterial meningitis
WBCs: High
Lots of PMNs
Glucose: low
Protein: High
CSF profile in viral meningitis
WBCs: High (but not as high as bacterial)
Lots of lymphocytes
Glucose: Normal
Protein: Normal or slightly elevated
Treatment of suspected bacterial meningitis in neonates
Ampicillin
+
Cefotaxime
Treatment of suspected bacterial meningitis in children and adults
Ceftriaxone or Cefotaxime
+
Vanco
Treatment of suspected bacterial meningitis in adults >50
Ceftriaxone or Cefotaxime \+ Vanco \+ Ampicillin
Corticosteroid administration in cases of suspected meningitis
Give before or at same time as 1st antibiotic
Common causes of viral meningitis
Enterovirus
HSV2
Arboviruses
Symptoms of viral meningitis
Headache, fever, meningeal irritation
Milder than bacterial
Diagnosis of viral meningitis
- CSF analysis
- PCR
- IgM if WNV
Viral encephalitis
Viral encephalitis is an infection of brain tissue rather than just subarachnoid space (meningitis). Signs/symptoms usually much more extensive than for meningitis.
Clinical symptoms of viral encephalitis
A. Common: Altered consciousness, fever, and headache.
B. Seizures and focal neurological signs/symptoms are common: personality change, alteration in mental status/level of consciousness (75-95%), aphasia (65-75%), hemiparesis (30-40%), ataxia (40%), cranial nerve palsies (30-35%), and visual field loss (10-15%).(% shown is for HSV encephalitis). Tremors, myoclonus, Parkinsonism seen in WNV.
Most common causes of viral encephalitis
Arboviruses and HSV
What is the goal when a pt walks in the door with suspected bacterial meningitis
Start Antibiotics within 60 minutes of patient arrival in the emergency room
Get blood cultures
Start corticosteroids
What to start immediately in suspected cases of viral encephalopathy?
Acyclovir
