CNS Infections Flashcards
What does the Pia and the Arachnoid make up?
Leptomeninges
What is infected with meningitis?
Leptomeninges
What does the Pia matter create?
Is the inner layer that is tightly adhered to the brain parenchyma which forms the Choroid Plexus, which makes CSF
What is important to do immediately after giving an epidural?
Optimize patient positioning to appropriately numb targeted area
Why is bacterial meningitis a can not miss diagnosis?
Without treatment within 24 hours can be fatal 70-100% of the time
Who is more likely to get bacterial meningitis?
Children < 2 months (but median age is 42- so really anyone)
What are some predisposing factors for bacterial meningitis?
Prior viral infection
Household crowding (college kids or military)
Active and passive smoking
Occupation risks (us and microbiologists)
What are the top three bacteria to cause bacterial meningitis?
S. pneumonia, N. meningitis, L. monocytogenes
What is the most common bacterial cause of meningitis in newborns?
Group B Strep
What is the most common bacterial cause of meningitis in teenagers?
N. meningitis
What is a common place of entry for bacterial organisms that go on to cause bacterial meningitis?
Nasopharynx up to optic chiasm
What are the the top three infections that lead to meningitis?
Otitis media, sinusitis, or dental infections
What is the most common place of BBB cross over in bacterial meningitis?
Choroid plexus and postcapillary veins
What is the inflammatory response for bacterial meningitis?
Further breakdown of the BBB, cerebral edema and increased ICP which can lead to herniation
What are the two N. meningitidis vaccines?
Meningococcal conjugate vaccine and MenB
What is the antibiotic of choice to treat bacterial meningitis caused by N. meningitidis?
Ceftriaxone
What is the antibiotic of choice to treat bacterial meningitis caused by S. pneumoniae?
Vancomycin plus ceftriaxone
What type of bacterial meningitis is most likely to have seizures?
Meningitis caused by Listeria Monocytogenes (older patients)
What is the antibiotic of choice to treat bacterial meningitis caused by listeria?
Ampicillin or Penicillin (if allergic, Bactrim)
What symptom (neurological deficit) seen in listeria meningitis?
Ataxia
What type of meningitis is most common in those that arn’t vaccinated?
Haemophilus Influenzae (most common in kids)
Why are neonates more susceptible to meningitis?
Have increased permeability of the BBB
What is the classic triad of presentation for bacterial meningitis?
Fever, stiff neck (nuchal cord rigidity), change in mental status (more lethargy)
How can babies present with meningitis?
Poor feeding, irritable, moaning cry, abnormal tone (abnormal posturing), vacant staring, lethargic, tense fontanelle, cyanosis
What two tests can you do as part of your physical exam to diagnose meningitis?
Brudzinski and Kernig signs
What is the rash that will classically present in N. meningitidis meningitis?
Petechiae and palpable purpura rash
What will you see on your CBC in meningitis?
Leukocytosis with Left Shift
May have thrombocytopenia
What labs are you going to order for working up bacterial meningitis?
CBC
Coagulation studies
CMP (elevated anion gap)
2 sets of blood cultures
Head CT
LP
?MRI (may show enhancements of the leptomeninges)
In real life (not textbook) are you ordering a CT when diagnosing meningitis?
YES! You need to rule out the other stuff that is going to be bad (abscess that would be contraindicated for an LP)
How does the patient need to be lying for a lumbar puncture?
Lateral decubitus
What are the contraindications for an LP in working up meningitis?
Anticoagulated
Concern for herniation (elevated ICP)
If platelets < 50,000
What is the normal glucose level of CSF?
45-85
What is the glucose in bacterial meningitis?
< 40 (low)
What is the color of bacterial meningitis vs. viral meningitis?
Turbid/cloudy in bacterial meningitis and clear with viral
What WBC is going to be elevated in viral meningitis?
Lymphocytes
What is the order of treatment for meningitis?
ABC’s
Start antibiotics and antivirals
Head CT
LP
Treat Shock
Start steroids (dexamethasone)
Exposure prophylaxis
What is the classic antibiotic (broad spectrum) regimen for antibiotics?
Ceftriaxone, Vancomycin, Ampicillin
Who else do you need to treat when someone is diagnosed with meningitis?
Anyone in close contact with patient for more than 8 hours of contact
How long does chronic meningitis last prior to presentation?
> 30 days
How does chronic meningitis present?
Often have cranial nerve findings and mental status change
What is aseptic meningitis most typically associated with?
Enterovirus
When is viral meningitis more common?
Summer and fall, enteroviruses most commonly peak in summer and fall
What viruses cause viral meningitis?
Enterovirus
Herpes Virus
Acute HIV
What two presenting symptoms are more common in bacterial meningitis than viral meningitis?
Photophobia and seizures are more common in bacterial
What is the treatment for viral meningitis?
Depends on virus (acyclovir)
Support patient with dark and quite room
Tylenol for HA, fever, pain
What can direct you to bacterial meningitis over aseptic meningitis or encephalitis?
CSF lactate >3.5mmol/L
What is encephalitis?
Inflammation of the brain parenchyma
What are the 6 V’s of encephalitis?
Vacation
Vaccination
Vectors
Viruses
Veterinary sources
Vital statistics (is there an outbreak)
Beside the overlapping symptoms with meningitis, how is a patient with encephalitis going to present?
Altered mental status (truly confused, agitated, obtunded, personality change)
Focal neurologic abnormalities
What is a major criteria diagnostic criteria for encephalitis?
AMS + 2 minor criteria (fever, seizure, neuro findings, CSF pleocytosis, parenchyma on MRI, EEG abnormality)
What imaging are you going to order for viral meningitis?
MRI, CT may look normal initially
What lobe is going to be typically involved in viral meningitis?
Temporal lobe
What is the treatment for viral meningitis?
Acyclovir all day long!
How is a brain abscess defined?
Focal collection of infection in the brain parenchyma
What are the typical infections of spread leading to a brain abscess?
Otitis media
Mastoiditis
Dental infection
What cranial nerve palsy is usually present in a brain abscess?
CN VI due to elevated ICP
Do you use contrast when looking for an abscess?
Yes
What broad spectrum coverage is used in treating a brain abscess?
IV Vancomycin
IV Metronidazole (anerobes)
IV Ceftriaxone
for 4-8 weeks
When is surgery indicated in a brain abscess?
Secondary to a TBI and material in the abscess
Fungal
Loculated (walls within the abscess)
No improvement after a week
Elevated ICP
Increased size
