Meningitis
Commonly Asked Questions
Stephen J. Gluckman, M.D.
What are normal CSF findings?
• Protein
– 0.45 gm/L
– Elevated with Diabetes
– Elevated with neuropathies of any cause
– Elevated with increasing age
– Elevated by bleeding into the CSF (SAH or
traumatic)
• 0.01 gm/L for every 1000 RBC’s
What are normal CSF findings?
• Glucose
– 60 % of blood glucose
• In persons with hyperglycemia it takes several
hours for CFS and blood glucose to equilibrate
– Low CSF glucose
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•
•
•
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Bacterial infection
Tuberculosis, cryptococcosis, carcinomatous
SAH
Sarcoidosis
Occasional viral
What are normal CSF findings?
• Cell count
– <5 WBC (all mononuclear) and < 5 RBC
considered “normal”
– Traumatic tap
• WBC/RBC ratio = 1:1000
• Pressure
– <20
• In patients with bacterial meningitis
– wide range
– 40% >30, 10% < 14
Can the CSF reliably distinguish between a
bacterial and non-bacterial cause of
meningitis?
Usually
Look at the whole pattern!
Can the CSF reliably distinguish between a
bacterial and non-bacterial cause of
meningitis?
• Glucose
– <2.5 suggests bacterial
– < 0.5 highly suggests bacterial
• Protein
– > 2.5 suggests bacterial
• Cell count
– >500 suggests bacterial
– >1000 highly suggests bacterial
• % polys
– >50 suggests bacterial
Are there exceptions?
• Early viral can have a predominance of
polys
• Some viral can have low CFS glucose
• Listeria can have predominance of
mononuclear cells rather than polys
• TB can have predominance of polys
How much does prior administration of
antibiotics alter the CSF findings?
Not Much
How much does prior administration of
antibiotics alter the CSF findings?
• 48-72 hours of prior intravenous antibiotic
treatment has little effect on glucose,
protein and cell count
– It will rarely change the CSF from a “bacterial”
to an “aseptic” formula
• Prior antibiotic treatment will likely make
the cultures negative.
What is the typical clinical presentation
of bacterial meningitis?
• History
– Headache: 75-90%
– Photophobia: uncommon
• Examination
– Fever: 95%
– Stiff Neck: 85%
– Altered mental status: 80%
– All three: 40%
– Any one of the three: 100%
How “good” are Kernig and
Brudzinski signs?
• Originally related to severe, advanced TB
meningitis (not bacterial)
• Not studied in a prospective study until
2002 (N=297)*
– Sensitivity 5%
– Specificity 95%
*Thomas KE et al. Clin Infect Dis. 2002;35:46-52
What are the common causes
of bacterial meningitis?
• It depends upon age and risk factors
– Age
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Neonates: listeria, group B streptococci, E. coli
Children: H. influenza
10 to 21: meningococcal
21 onward: pneumococcal >meningococcal
Elderly: pneumococcal>listeria
– Risk factors
• Decreased CMI: listeria
• S/P neurosurgery or opened head trauma: Staphylococcus,
Gram Negative Rods
• Fracture of the cribiform plate: pneumococcal
What is the proper empirical antibiotic
regimen for presumed bacterial meningitis?
It depends upon the clinical situation
What is the proper empirical antibiotic
regimen for presumed bacterial meningitis?
• Neonates
– 3rd generation cephalosporin and ampicillin
• Children
– 3rd generation cephalosporin
• Normal adult
– 3rd generation cephalosporin and vancomycin (if resistant
pneumococci)
• Problems with cell mediated immunity (AIDS, steroids,
elderly)
– Add coverage for listeria with ampicillin or co-trimoxazole
• S/P CNS trauma or neurosurgery
– Coverage for staphylococcus and gram negative rods with
antipseudomonal beta-lactam and vancomycin
How important is the speed of initiating
antibiotics in bacterial meningitis?
It is important
But it is not the critical prognostic factor
How important is the speed of initiating
antibiotics in bacterial meningitis?
• The clinical outcome is primarily
influenced by the severity of the illness at
the time antibiotics are initiated
– Severity based on
• Altered mental status
• Hypotension
• Seizures
How important is the speed of initiating
antibiotics in bacterial meningitis?
• No factors
– 9% with adverse outcome
• One factor
– 33% with adverse outcome
• Two or three factors
– 56% with adverse outcome
Therefore, though treatment should be
administered ASAP, the impact of antibiotic
delay is a function of the severity of disease at
the time that treatment is initiated
Steroids or no Steroids?
Steroids
(today)
Steroids or no Steroids?
• Reduces morbidity and mortality*
• Give before or at the same time as the first
dose of antibiotics
• Dose studied
– Dexamethazone 10 mg Q6H x 4 days
*Only shown for pneumococcal meningitis in
adults and haemophilus meningitis in children
Do you need to do a CT scan
before an LP?
Usually not
• A CT scan should never delay therapy
(obtain blood cultures)
Do you need to do a CT scan
before an LP?
• Prospective studies*
– N = 412
– Predictors of CNS mass lesion
• History
– > 60 years old
– Immunocompromised
– Hx of prior CNS disease
– Hx of seizure w/in 1 week prior to onset
• Examination
– Focal neurological findings
– Altered mental status
– Papilledema
*Gopal et al. Arch Intern Med. 1999;159:2681-5
Hasbun and Abrahams. N Engl J Med 2001:345:1727-33
How contagious is meningitis?
Are we at risk when we care for a patient?
• Not really
• The only bacterial meningitis that is spread
from person to person is meningococcal
– The risk is very low
• Household contacts have about a 1% risk
• Health care workers have not been shown to have
a risk
• After 24 hours of treatment this is no risk
What is “Aseptic” meningitis?
• It is a term used to mean non-pyogenic
bacterial meningitis
• It describes a spinal fluid formula that
typically has:
– A low number of WBC
– A minimally elevated protein
– A normal glucose
• It has a much bigger differential diagnosis
than viral meningitis.
What are the
treatable causes of aseptic
meningitis/encephalitis syndrome?
• Infectious
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–
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–
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HSV 1 and 2
Syphilis
Listeria (occasionally)
Tuberculosis
Cryptococcus
Leptospirosis
Cerebral malaria
African tick typhus
Lyme disease
• Non-Infectious
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–
–
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Carcinomatous
Sarcoidosis
Vasculitis
Dural venous sinus
thrombosis
– Migraine
– Drug
• Co-trimoxazole
• IVIG
• NSAIDS
What are the important things to know about
AIDS- associated cryptococcal meningitis?
• Generally advanced with CD4 < 100
• Sub-acute onset: fever, headache
– Stiff neck is rare
• Mortality with treatment is about 15%!
– Predictors of death
• Altered Mental status, low CSF WBC count, high
CSF cryptococcal antigen titer
What are the important things to know about
AIDS- associated cryptococcal meningitis?
• CSF findings
– Elevated pressure is the usual (>70%)
– Rest of CSF findings are often unimpressive
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WBC <50
Glucose: normal or slightly low
Protein: normal or slightly elevated
25% have normal WBC, glucose and protein
– CSF cryptococcal antigen: 95-100% sensitive
What are the important things to know about
AIDS- associated cryptococcal meningitis?
• Treatment
– Medical
• Induction: amphotericin B 0.7mg/kg x 2/52
– (flucytosine)
• Consolidation: fluconazole 400 mg x 8/52
• Maintenance: fluconazole 200 mg
– Pressure
• Daily LP’s to keep opening pressure <20
• If LP’s are still needed after 1 month
shunt
Questions from the Audience?
Meningitis – Who was awake?
Which of the following are true statements?
a. Early viral meningitis can have a
predominance of polys
b. Some viral meningitis can have low CSF
glucose
c. Listeria meningitis can have predominance of
mononuclear cells rather than polys
d. All of the above
Meningitis – Who was awake?
Which of the following are true statements?
a. Early viral meningitis can have a
predominance of polys
b. Some viral meningitis can have low CSF
glucose
c. Listeria meningitis can have predominance of
mononuclear cells rather than polys
d. All of the above
Meningitis – Who was awake?
To correct CSF protein concentrations for blood in
the CSF the proper ratio is approximately 0.01
gm/L of protein for every 100 RBC’s
a. True
b. False
Meningitis – Who was awake?
To correct CSF protein concentrations for blood in
the CSF the proper ratio is approximately 0.01
gm/L of protein for every 100 RBC’s
a. True
b. False
Meningitis – Who was awake?
• Which of the following are true about
cryptococcal meningitis?
– a. A normal CSF effectively rules out
cryptococcal meningitis
– b. If the CSF pressure is elevated one should
not remove more than 10 ml at a time
– c. Everyone with HIV infection is at increased
risk for cryptococcal meningitis.
Meningitis – Who was awake?
• Which of the following are true about
cryptococcal meningitis?
– a. A normal CSF effectively rules out
cryptococcal meningitis
– b. If the CSF pressure is elevated one should
not remove more than 10 ml at a time
– c. Everyone with HIV infection is at increased
risk for cryptococcal meningitis.
None