CNS infections Flashcards
presentation of meningitis?
meningism:
- HA
- photophobia
- neck stiffness
how does bacterial meningitis usually arise?
local spread from the sinuses, the nasopharynx or the ear
most common causative pathogen in bacterial meningitis in
1) neonates
2) infants
3) children/ adolescents
4) adults
5) elderly
1) group B strep
2) N.meningitides
3) N.meningitides
4) strep. pneumonie
5) strep. pneumonie
most likely causative pathogen in bacterial meningitis in
1) fractured cribiform plate
2) neurosurgery/ head trauma
3) pregnancy
1) strep pneumonie
2) staph aureus and epidermidis
3) listeria monocytogenes
what bacterial cause of meningitis is this:
1) gram negative diplococcus
2) gram positive coccus
3) gram negative coccobacillus
4) beta heamolytic gram positive flagellated rod
1) N. meningitides
2) strep. pneumoniae/ group B strep
3) haemophilus influenza B
4) L. monocytogenes
Bacterial meningitis clinical features?
meningism: HA, photophobia, neck stiffness
fever
Kernigs sign (resists knee extension when hip flexed)
Brudzinksi’s sign (neck flexion causes hip and knee flexion)
Tumbler test +ve
NB: viral is same but fever may be less pronounced
what type of bacterial meningitis is the tumbler test most commonly +ve in?
meningococcal septicaemia
what Ix is also done pre-LP in meningitis?
CT: to rule out increased ICP. Always done pre-LP to prevent coning
treatment of community acquired meningitis?
1) normal circumstances
2) if listeria is suspected (>55/ neonate/ immunosuppressed)
1) IV ceftriaxone + dexamethasone with first dose
2) add amoxicillin for cover
why is dexamethasone given in community acquired meningitis?
reduce long term complications, esp deafness
prophylactic therapy for those in close contact with the meningitis patient?
ciprofloxacin
rifampicin 2nd line
T/F: viral meningitis is a form of aseptic meningitis
true (culture negative)
common causes of viral meningitis?
commonly enteroviruses (e.g. echovirus)
more severe infection: HSV (can progress to encephalitis)
Ix in viral meningitis?
LP: clear, raised lymphocytes, normal protein, low/ normal glucose
treatment of viral meningitis?
normally self limiting
IV acyclovir if severe
how does presentation of TB meningitis vary from typical bacterial meningitis?
features of meningism not always present, can present with more general features e.g. headache and fever
characteristic CSF findings in TB meningitis?
clear and culture negative CSF, lymphocytosis, high protein, low glucose, fibrin webs
what is encephalitis?
inflammation of the brain parenchyma commonly caused by viral infection
most common cause of encephalitis?
HSV - tends to spread through olfactory nerve/ from reactivation of the trigeminal root ganglion
clinical features of encephalitis?
acute onset HA, fever, altered consciousness, focal neuro deficit (aphasia, hemiplegia, visual field defect), meningism
in encephalitis, certain features suggest a particular aetiology
1) seizures with focal neurological deficits (aphasia)
2) parotitis in an unvaccinated patient
3) skin lesions/ vesicles in a dermatomal pattern
1) HSV
2) mumps
3) VZV
Ix in encephalitis?
CT: cerebral oedema
MRI: oedema in temporal lobes (HSV)
CSF PCR
treatment of encephalitis?
IV acyclovir
Subacute sclerosing panencephalitis:
An uncommon but serious sequalae of the ____ virus where the onset can be as
late as ____ after the initial infection. It tends to present how?
measles
years
change in personality, cognitive decline, myoclonus: reflecting the diffuse cortical involvement
CSF findings in 1) bacterial meningitis 2) viral menigitis 3) TB meningitis (appearance, opening pressure, cells present, protein, glucose)
1) cloudy, elevated opening pressure, neutrophils, high protein, low glucose
2) clear, normal opening pressure, lymphocytes, high protein, normal glucose
3) opaque (forms fibrin web if left to settle), elevated opening pressure, lymphocytes, high protein, low glucose
CSF findings in
1) MS
2) GBS
3) Alzheimer’s
4) subarachnoid haemorrhage
1) oligoclonal bands
2) high protein
3) increased phosphorylated tau protein, decreased B-amyloid
4) xanthochromia
CSF findings in
1) creutzfeldt-jakob disease
2) idiopathic intracranial hypertension
3) narcolepsy
1) elevated 14-3-3 protein
2) high opening pressure
3) low/ undetectable levels of CSF orexin/ hypocretin
diagnosis of Subacute sclerosing panencephalitis:?
often clinical
MRI can characterise involvement
CSF may show raised IgG anti-measles Abs (chronic infection)
