Meningitis/encephalitis Flashcards
meningitis
general
Inflammation of the pia mater, arachnoid, and CSF-filled subarachnoid space
Characterized by CSF pleocytosis (increased cell count)
Bacterial
Neisseria meningitidis
Strep pneumoniae
Haemophilus influenzae
Group B Strep
Listeria monocytogenes
Aseptic
viruses
fungi
protozoa
drugs
systemic disorders
Meningitis
patho
Invasion of bloodstream (bacteremia, viremia, fungemia, parasitemia) and subsequent hematogenous seeding of CNS
Most common mode of spread, characteristic of meningococcal, cryptococcal, syphilitic, and pneumococcal meningitis.
Direct contiguous spread (sinusitis, otitis media, trauma, direct inoculation during intracranial manipulation)
Local extension from contiguous extracerebral infection (otitis media, mastoiditis, sinusitis) is common cause.
Retrograde neuronal pathway (olfactory and peripheral nerves)
Meningitis
newborns and infection
Meningitis in newborn may be transmitted vertically, involving pathogens that have colonized the maternal GI or genital tract, or horizontally, from caregivers.
bacetrial meningitis
Most common bacteria and second most
Strep pneumoniae
Most common: >50% of US bact meningitis cases (2000/year)
Leading cause of bact meningitis in children < 5 y.o.
Neisseria meningitidis
Second most common
Close contact outbreaks, adolescents (dorms/barracks)
15% death rate; 20% of survivors have disabilities (limb loss, deafness, neuro problems)
bacterial meningitis
clin man
Triad
Triad
Fever
HA (in over 80%)
Nuchal Rigidity
Fourth symptom can be AMS (Altered Mental Status; confused, lethargic)
95+% of patients at least two of these four
May be photophobia, N/V
Short time from onset to presentation: less than 24 hours in 25%
Bacterial Meningitis
Physical Exam Findings
Fever
Meningismus
+ Kernig and Brudzinski
Nuchal Rigidity
Chin to chest
Seizures: 30-50%
Focal Neuro Deficits - CN deficits ~25% (CN VI, then III, IV VIII)
Papilledema: rare
Skin Rashes: Meningococcal
Petechial esp with meningococcal septicemia
Meningitis signs
Kernig and brudszinski
Papilledema
meningitis
Meningococcal Meningitis
Clin man
- Fever, headache, vomiting, delirium, convulsions.
- Petechial rash on skin and mucous membranes in many.
- Neck and back stiffness and positive Kernig and Brudzinski signs are characteristic.
- Purulent spinal fluid with gram-negative intracellular and extracellular diplococci.
- Culture of cerebrospinal fluid, blood, or petechial aspiration confirms the diagnosis.
meningitis
Head CT before LP
Immunocompromised state (HIV infection, immunosuppressive therapy, transplantation)
History of CNS disease (mass lesion, stroke, focal infection)
New onset seizure (within one week of presentation)
Papilledema
Abnormal level of consciousness
Focal neurologic deficit
Bacterial Meningitis
LP results
glucose will be low
opeining pressure will be elevated
Protein will be very high
few RBCs
Viral meningitis
LP results
opening pressure - slightly elevated
< 200/mm WBC
Glucose will be normal
protein will be normal
no RBC
Bacterial vs. Viral Meningitis
Bacterial meningitis highly probable when any one of the following CSF parameters present:
Glucose <34 mg/dL
Protein concentration >220 mg/dL
WBC count >2,000 microL
Neutrophil count >1180 microL
But many exceptions: empiric antibiotics warranted when bacterial meningitis is suspected clinically even if CSF abnormalities are not diagnostic
bacterial meningitis
Dx
CBC
CMP
Glucose for comparison with CSF
Liver and kidney function to adjust dosing
PT/PTT?; Lactic Acid?; HIV testing? Syphilis testing?
Blood Cultures X 2
Positive in majority of bacterial meningitis patients
Guide therapy if CSF not available
Urine (UA & CX)
Imaging
CXRay