CNS infections Flashcards
meningitis definition
inflammation of meninges
encephalitis definition
inflammation of the brain parenchyma
brain abscess definition
collection of pus
presents lie a stroke bc is focal
which of the following presents diffusely and which presents like a stroke (bc is focal);
meningitis
encephalitis
brain abscess
meningitis - diffuse
encephalitis - diffuse
brain abscess - focal (collection of pus)
what are the 4 main causes of bacterial meningitis
strep pneumoniae
Neisseria meningococcus
haem influenzae
listeria monocytogenes
who gets bacterial meningitis caused by strep pneumonia
most people! - its the most common cause
also cochlear implants, sinusitis - as its normally found in the nasopharynx
who gets bacterial meningitis caused by Neisseria meningococcus
10-20yos
students
who gets bacterial meningitis caused by haem influenzae
kids
who gets bacterial meningitis caused by listeria monocytogenes (2)
immunocompromised people ge HIV, >60yo, alcoholics, pregnant women, neonates
recently eaten soft cheese (or other deli products - grows at fridge temp) - lol our fridge juice is listeria
which bacteria is most the most common cause of bacterial meningitis
strep pneumoniae
which cause of bacterial meningitis is a Gm+ve (purple) diplococci on histology
strep pneumonia
2 purple circles
which cause of bacterial meningitis is a Gm-ve (pink)intracellular whisps on histology
Neisseria meningococcus
will probs be described not picture bc hard to see whisps
which cause of bacterial meningitis is a Gm-ve (pink) bacilus on histology
haem influenzae
pink rod
which cause of bacterial meningitis is a Gm+ve bacillus on histology
listeria monocytogenes
purple rod
causes of aseptic (non bacterial) meningitis
viruses!
enterovirus (ECHO)
EBV
CMV
HIV
travel history important!
also sarcoidosis, cancer, vasculitis…
do bacterial or aseptic meningitis more classically present with a rash
bacterial (though not always)
diagnostic investigation for aseptic meningitis
CSF PCR form lumbar puncture
treatment of aseptic (non bacterial) meningitis
supportive
IV Aciclovir if ?abscess
what type of rash does bacterial meningitis classically present with
non blanching purpuric rash
what does non blanching rash mean
when you put a clear glass over it the rash remains
presentation of meningitis
non blanching purpuric rash - if bacterial fever seizure stiff neck headache photophobia
what is kernigs sign
when you get patient to lie down and bend one knee with hip at 90 degrees, then try straighten knee = too painful
what is kernigs sign positive of
meningitis
is bacterial or viral meningitis more slow in onset
viral
is bacterial or viral meningitis faster in onset
bacterial
what other neuro condition does meningitis present similar as (but headache not as bad)
subarachnoid haemrrhage
investigations for meningitis
CT and antibiotics first
lumbar puncture - look at CSF
what is the purpose of doing a lumbar puncture if youre fairly sure diagnosis is meningitis
differentiates between bacterial and viral - diff treatments
cloudy lumbar puncture in meningitis
viral/bacterial infection?
bacterial infection
clear/translucent lumbar puncture in meningitis
viral/bacterial infection?
viral infection
what investigations do you want to do after CSF sample obtained for meningitis (6)
Gm stain and culture viral PCR cell count - lymphocytes and neutrophils glucose protein pressure
high neutrophils in meningitis
viral/bacterial infection?
bacterial infection
high lymphocytes in meningitis
viral/bacterial infection?
viral infection
think about EBV and its atypical lymphocytes!
low glucose (<60% of blood glucose) in CSF in meningitis
viral/bacterial infection?
bacterial infection - bc bacteria eat up glucose for energy
normal glucose (>60% of blood glucose) in CSF in meningitis
viral/bacterial infection?
viral infection - bacteria eats up the glucose = low
acute treatment of meningitis
ABCDE
antibiotics and steroids - before you get results back
which antibiotic do you give for meningitis
ceftriaxone
what do you give alongside the ceftriaxone in ?bacterial meningitis
dexamethasone (steroid)
which alternative antibiotic do you give (instead of ceftriaxone) to patient you suspect listeria in
who do you suspect listeria in
amoxicillin
immunocompromised
what would you give instead of antibiotics when you confirm a viral cause of meningitis
acyclovir
complication of untreated meningitis
brain abscess
sepsis
IS A MEDICAL EMERGENCY
which CNs are at risk of being damaged if a brain abscess occurs after meningitis
CN III and VI
what prophylaxis is given to people who have been in close contact and prolonged exposure with someone with bacterial meningitis
ciprofloxacin
what public health intervention is used to try and reduce cases of meningitis
MenACWY vaccines given to adolescents
what is the most common cause of encephalitis
herpes simplex virus
which lobe is commonly affected in encephalitis
temporal lobe
how does encephalitis present
sudden onset
fever/flu like illness
altered behavior (bc temporal lobe) new onset seizures
recent travel!
investigations for encephalitis
lumbar puncture
CT
EEG - for seizures
MRI
treatment of encephalitis
ABCDE
acyclovir
what are the risk factors for developing a brain abscess
current infection eg ear infection, sinusitis
jaw trauma
someway for bugs to get into cranial cavity!
how does a brain abscess look on CT
‘ring enhancing lesion’ - the contrast cant pass through the centre of the abscess bc so dense = looks like a ring
treatment of brain abscess
ceftriaxone IV and metronidazole IV
