brain abscesses and other infections of the central nervous system Flashcards
define brain abscess
focal suppurative process within the brain parenchyma
what are the main causes of brain abscess
bacterial
fungal
polymicrobial
what is the main bacterial pathogen which causes brain abscesses
streptococci (streptococcus milleri)
what 4 clinical settings do brain abcessess develop in.
direct spread- continuous supparative focus e.g. ear or sinus.
Haematogenous spread from a distant focus via bloodstream e.g. endocarditis (heart), bronchiectasis (lungs) (often multiple abscesses).
Trauma- post neurosurgery
Cryptogenic (no known cause)- no focus, commonly found in immunocompromised people as they have had the breakdown of the muscosal barrier and have access devices such as hickman lines.
clinical presentation of patient with brain abcesses
headache- most common focal neurological deficit confusion- generalised neurological deficit. fever nausea and vommitting dizziness, seizures neck stiffness (papilloedema), coma- optic nerve swelling.
main treatment of choice for brain abscess
drainage
is the abscess in small drainage may not be used as treatment, what might be used ins tea
antibiotics
why is drainage the best option for treatment of brain abscess.
reduce ICP- can causes seizures and coms
confirm diagnosis- CT not 100%
obtain pus fro micobiological investigation.
to enhance efficacy of antibiotics
to avoid spread of infection to ventricles.
why are oral ampicillin, penicillin not used to treat brain abscesses.
they are not targeted to the right place. e.g. CSF and CNS
which antibiotics are used to treat brain abscesses.
cefuroxime (penetrate brain and CSF))
cefotaxime, ceftazidime (works against pseudomonal aspergilloma)
metronidazole achieve therapeutic concentrations in intracranial pus
unto how many weeks after surgery are antibiotics given to patients who had a brain abscess
4-6 weeks and then have a oral switch.
complications of a brain abscess
Raised intracranial pressure, mass effect.
Rupture (usually into ventricles) causing ventriculitis
what is the mortality rate if the brain abscess speeds to the ventricles
100%
define subdural empyema
Infection between dura and arachnoid mata-
most common pathogenic organisms to cause subdural empyema
often polymicrobial
anaerobes, streptococci, aerobic gram negative bacilli, streptococcus pneumoniae, haemophilius influenza and staphylococcus aureus (after surgery)
pathogenesis of subdural empyema
spread of primary infection from sinuses (most common) , middle ear and mastoid or distant site` and following surgery or trauma- but it does not enter the brain parenchyma it is stopped by the dura.
most common site of origin of infection of subdural empyema
sinuses
what is the clinical presentation of a patient with subdural empyema
headache, fever, focal neurological deficit, confusion, seizure, coma due to increased pressure.
how is subdural empyema treated
surgical drainage of pus antimicrobial agents (guided by culture of pus results)
Is a Ventriculoperitoneal (VP) shunt permanent or temporary
permanent
what age groups present with Ventriculoperitoneal (VP) shunt
children
is a external ventricular drain (EVD) permanent of temporary
temporary.
in what conditions is a external ventricular drain (EVD) inserted to drain CSF
hydrocephalus.
how can Ventriculoperitoneal (VP) shunt and external ventricular drain (EVD) cause infection.
can become colonised with organisms that subsequently cause ventriculitis (often peritonitis)
