Meningitis Flashcards
what drug caused big decrease in mortality of meningitis
penecillin
what is the mortality rate of meningitis
10-100%
5 disabilities caused by meningitis
- deafness
- paralysis
- speech problems
- epilepsy
- neuro-psychiatric problems
where is csf produced
choroid plexus in the ventricles
order of meninges out-in
DAP
Dura
arachnoid
pia
define meningitis
inflammation of lepto-meningeal membranes
4 infectious causes of meningitis and examples
virus (enterovirus, mumps (zosterovirus), herpes)
bacteria (meningococci, pneumococci, h influenzae)
fungus (cryptococcus neoformans, coccidiodomycosis)
parasitic (naegleria fowleri, acanthamoeba)
3 routes by which organisms reach the cns
- bacteraemia/ viraemia/ parasitaemia: in the blood, esp through choroid plexus
- direct spread: chronic infections in cranial bones, ears, sinuses, oral cavity or upper resp tract
- neuronal spread: infection of peripheral neurones, axonal transport, replication and cell-cell spread of infection to connecting neurones on CNS
flowchart of meningitis pathogenesis 9 (see lecture)
mucosal colonisation –>
intravascular survival –>
meningeal invasion –>
survival in subarachnoid space –>
inflammatory response, inc BBB permeability, cerebral vasculitis –>
oedema, CSF flow disturbances –>
inc intracranial pressure, dec cerebral blood flow –>
loss of cerebro-vascular autoregulation –>
coma, death
4 factors influencing cause of bacterial meningitis
- age ( BBB not fully formed. >75, BBB weakens)
- geography (overcrowding, high temp –> epidemics)
- immunity (chemo/ transplants/ steroids)
- trauma/ post-neurosurgical (esp base of skull, as oropharyngeal trauma enter skull)
why do neonates have different bacterial causes of bacterial meningitis to other age groups?
due to mothers bacteria during birth
what are the common bacterial causes of bacterial meningitis in >50s, immunocomp, basilar skull fracture 2
s pneumoniae
n meningitidis
additional bacteria in
a. >50/immunocompromised
b. basilar skull fracture
a. >50/immunocompromised: listeria, gram - bacilli, pseudomonas aeruginosa (immunocomp)
b. basilar skull fracture: group A beta-hemolytic strep
4 bacterial causes of head injury/ post neurosurgery meningitis and why these are different to most
-s aureus
-s epidermis
-aerobic gram - bacilli
-p aeruginosa
oropharyngeal/ skin flora
5 symptoms of meningitis
- fever
- neck stiffness
- altered mental state
- headache
- photophobia
3 signs of meningitis
- neck rigidity
- kernigs sign
- brudzinski’s sign
problems with
A. signs
b. symptoms of meningitis
a. signs: common to many illnesses, normally not all present in meningitis
b. symptoms: only 5% sensitivity
what is the gold standard test in CNS infection diagnosis
lumbar puncture
normal csf:
a. colour
b. opening pressure
c. lymphocyte count
d. protein
e. glucose
f. gram stain
g. culture
a. colour: clear
b. opening pressure: 5-20cm
c. lymphocyte count: 60% of blood glucose
f. gram stain: NOS
g. culture: sterile
csf findings in meningitis TABLE
when is a CT/ MRI scan needed before lumbar puncture 3
and WHY
- fitting
- focal neurological disorder
- dec on coma scale
- -> may be something else where lumbar puncture contraindcated, eg cerebral tumour, subarachnoid haemorrhage, frontal sinusitis
6 indications of neuro-imaging in meningitis
- history of unconsciousness
- history of seizures
- focal neurology
- low gcs
4 main complications of bacterial meningitis and explain each
- seizures (scar epilepsy): scarring of brain tissue are foci of epileptic activity
- hydrocephalus: thickened CSF/ fibrinoid accumulations –> CSF builds up in brain –> pressure on brainstem –> cardiorespiratory arrest
- infarcts:vascular pressure/ vasculitis –> failed blood supply –> tissue dies –> haemoplegia, palsy
- transtentorial herniation: inc intracranial pressure –> pressure on brainstem (resp and motor centres) –> coma, death
management of meningitis 5
- supportive care
- specific antimicrobial therapy
- steroids
- surgical intervention
- prophylaxis
6 aspects of supportive care of meningitis
- airway
- breathing
- circulation
- nutrition
- physiotherapy
- rehabilitation
6 considerations of specific antimicrobial therapy for meningitis
- pathogen
- sensitivities/ resistance of pathogen
- csf penetration
- allergy, renal function etc
- route (IV, IT, IM, PO)
- duration of therapy
name antibiotics with good penetration 4
- penicillin
- ceftriaxone
- meropenem
- chloramphenicol
name antibiotics with poor penetration 2
vancomycin
gentamycin
when to use steroids to treat meningitis
BEFORE anything else (antibiotics, lumbar puncture etc)
2 roles of neurosurgery in meningitis management
- definitive (eg must drain csf in hydrocephalus)
- supportive: for IT antibiotics, external ventricular drain (EVD)
2 prophylaxis methods of meningitis
antibiotics
vaccines