Flashcards in Infections of Nervous System Deck (72):
what may untreated CNS infection cause?
brain herniation and death
cord compression and necrosis with subsequent permanent paralysis
what is bacterial meningitis?
infection of brain meninges
what are the two types of meningitis?
acute pyogenic (bacterial) meningitis
acute aseptic (viral) meningitis
what causes meningitis in neonates?
group B strep
what causes meningitis in children?
what causes meningitis in ages 10-21?
what causes meningitis in ages >21?
strep pneumoniae > neisseria meningitidis
what causes meningitis in ages >65?
strep pneumoniae > listeria
what causes meningitis in those with decreased cell mediated immunity?
what causes meningitis in those with head trauma / post neurosurgery?
gram negative bacilli
what causes meningitis in those with fracture of cribiform plate?
what causes meningitis in those with CSF shunt?
what is the three main ways bacterial meningitis can colonise?
direct extension of bacteria (from parameningeal foci or across skull defects)
from remote foci of infection (endocarditis etc)
what is the pathology of bacterial meningitis?
thick layer of suppurative exudate which covers leptomeninges over surface of brain
also exudate in basal and convexity surface
what is present in subarachnoid space in bacterial meningitis?
what are the symptoms of bacterial meningitis?
change in mental state
what is gold standard for diagnosis of meningitis?
lumbar puncture - send 4 tubes away
in what cases would you give a CT before lumbar puncture?
history of CNS disease
new onset seizure
papilloedema (raised ICP)
altered level of consciousness
focal neurological deficit
what additional investigations may you carry out in suspected bacterial meningitis?
FBC + coagulation screening
throat swab = meningococci
what is given as empirical treatment before lumbar puncture in bacterial meningitis?
10 days of ceftriaxone IV 2g bd and dexamethasone IV 10mg
penicillin allergic = chloramphenicol IV 25mg
what is the treatment once meningococcus (neisseria meningitidis) confirmed?
ceftriaxone (5-7 days)
what is given when pneumococcus confirmed?
ceftriaxone (10-14 days)
4 days dexamethasone
what is given if listeria suspected (if >60 or immunocompromised)?
amoxicillin IV 2g hourly
allergic = co-trimoxazole IV 120mg
what is given when H influenzae confirmed?
10 days ceftriaxone
what do you add to treatment if patient has recently travelled to places with penicillin resistant pneumococcal?
vancomycin IV or rifampicin IV / PO
when would a hospital admission be required for bacterial meningitis?
signs of meningeal irritation
impaired conscious level
febrile or unwell and have had a recent fit
any illness (especially headache) and are close contacts of patients with meningococcal infection, even if they have received a prophylactic antibiotic
what measures can be taken to try and prevent secondary cases of bacterial meningitis?
telephone reporting to public health
GPs informed to locate close contacts to implement chemoprophylaxis and vaccination
what are the 3 options which can be given as contact prophylaxis of bacterial meningitis?
rifampicin PO 12-hourly for four doses (adults and children >12 years)
ciprofloxacin PO single dose for adults and children >12 years
ceftriaxone IM single dose in adults, IV single dose in children under 12 years
what are side effects of rifampicin?
reduced efficacy of oral contraceptives
red colouration of urine
staining of contact lenses
what are the complications of bacterial meningitis?
ventriculitis / hydrocephalus
where does purulence occur when it is a complication of bacterial meningitis?
clusters at base of brain
convexities of rolandic and sylvian sulci
exudate around cranial nerves (esp III and VI)
how does invasion occur when it is complication of bacterial meningitis?
pia prevents meningitis becoming abscess
abscesses can cause secondary ventriculitis and hence meningitis
where is neisseria meningitidis usually found in healthy carriers?
how does neisseria meningitidis probably gain access to the meninges?
are the symptoms of neisseria meningitidis are usually due to exotoxin or endotoxin?
who does neisseria meningitidis most often cause disease in?
to prevent epidemics of neisseria meningitidis in training camps, military recruits are vaccinated with what?
purified capsular polysaccharide
as well as meningitis, what else can meningococcal infection cause?
local - conjunctivitis, arthritis
meningitis with septicaemia
where is H influenzae normally found?
what type of H influenzae is most common cause of meningitis in children under 4?
where is strep pneumoniae commonly found?
who is most susceptible to pneumococcal meningitis?
patients with CSF skull fractures
diabetics / alcoholics
there is some evidence that pneumococcal meningitis is related to CNS devices such as what?
does the conjugate vaccine for pneumococcal pneumonia also protect against pneumococcal meningitis in children?
who does listeria monocytogenes meningitis usually occur in?
immunosuppressed especially malignancy
what type of bacteria is listeria monocytogenes?
gram positive bacilli
what vaccination is available for neisseria meningitidis?
serogroups A and C (W135 and Y)
commonly used in travel vaccination
what vaccination is available for haemophilus influenzae meningitis?
what vaccination is available for streptococcus pneumoniae meningitis?
pneumococcal vaccines (polysaccharide and conjugate)
what is more common - bacterial or viral meningitis?
when does viral meningitis most commonly occur?
late summer / autumn
what causes viral meningitis?
enteroviruses eg ECHO
other microbes and non-infectious causes
how is viral meningitis diagnosed?
viral stool culture
how is viral meningitis treated?
supportive - self limiting
what is aseptic meningitis?
this is a term used to mean non-pyogenic bacterial meningitis
what is the characteristics of the spinal fluid in aseptic meningitis?
what causes aseptic meningitis?
dural venous sinus thrombosis
drugs - co-trimox, IVIG, NSAIDs
what infection must you not forget is a cause of aseptic meningitis?
what is encephalitis?
infection of brain parenchyma
what are the symptoms of encephalitis?
seizures, partial paralysis
speech, memory symptoms
focal or diffuse neurological signs
what is most common virus which causes encephalitis?
how is encephalitis diagnosed?
how do you treat encephalitis?
what is tuberculosis meningitis?
meningitis caused by M tuberculosis
who does tuberculosis meningitis usually affect?
elderly as reactivation
what are symptoms and investigation results in tuberculosis meningitis?
often non-specific ill health
previous TB on CXR
poor yield from CSF
what is treatment of tuberculosis meningitis?
isoniazid + rifampicin key
add pyrazinamide + ethambutol
what is cryptococcal meningitis and who does it usually occur in?
fungal type of meningitis which usually occurs in those with HIV
what is the CD4+ value in cryptococcal meningitis?
what are the symptoms of cryptococcal meningitis?
subtle neurological presentation
disseminated infection symptoms
what investigations should take place in cryptococcal meningitis?
CSF - aseptic
serum and CSF cryptococcal antigen