Infections of Nervous System Flashcards
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?
listeria
group B strep
E. coli
what causes meningitis in children?
H influenzae
what causes meningitis in ages 10-21?
neisseria meningitidis
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?
listeria monocytogenes
what causes meningitis in those with head trauma / post neurosurgery?
staphylococcus
gram negative bacilli
what causes meningitis in those with fracture of cribiform plate?
strep pneumoniae
what causes meningitis in those with CSF shunt?
staph epidermis
staph aureus
aerobic GNR
propionibacterium acnes
what is the three main ways bacterial meningitis can colonise?
nasopharyngeal colonisation
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?
neutrophils
what are the symptoms of bacterial meningitis?
fever neck stiffness change in mental state headache rash papilloedema (3%)
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?
immunocompromised 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?
blood cultures
FBC + coagulation screening
swab rash
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)
stop dexamethasone
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
stop dexamethasone
allergic = co-trimoxazole IV 120mg
what is given when H influenzae confirmed?
10 days ceftriaxone
stop dexamethosone
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
petechial rash
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?
purulence
invasion
cerebral oedema
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?
throat
how does neisseria meningitidis probably gain access to the meninges?
blood stream
are the symptoms of neisseria meningitidis are usually due to exotoxin or endotoxin?
endotoxin
who does neisseria meningitidis most often cause disease in?
young children
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
fulminant septicaemia
where is H influenzae normally found?
throat
what type of H influenzae is most common cause of meningitis in children under 4?
type b
where is strep pneumoniae commonly found?
throat
who is most susceptible to pneumococcal meningitis?
hospitalised patients
patients with CSF skull fractures
diabetics / alcoholics
young children
there is some evidence that pneumococcal meningitis is related to CNS devices such as what?
cochlear implants
does the conjugate vaccine for pneumococcal pneumonia also protect against pneumococcal meningitis in children?
yes
who does listeria monocytogenes meningitis usually occur in?
neonates
>55
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?
HiB vaccine
what vaccination is available for streptococcus pneumoniae meningitis?
pneumococcal vaccines (polysaccharide and conjugate)
what is more common - bacterial or viral meningitis?
viral
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
throat swab
CSF PCR
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?
low WBC
elevated protein
normal glucose
what causes aseptic meningitis?
infection carcinomatous sarcoidosis vasculitis dural venous sinus thrombosis migraine drugs - co-trimox, IVIG, NSAIDs
what infection must you not forget is a cause of aseptic meningitis?
HSV
what is encephalitis?
infection of brain parenchyma
what are the symptoms of encephalitis?
insidious onset meningismus stupor, coma seizures, partial paralysis confusion, psychosis speech, memory symptoms focal or diffuse neurological signs
what is most common virus which causes encephalitis?
HSV
how is encephalitis diagnosed?
lumbar puncture
EEG
MRI
how do you treat encephalitis?
pre-emptive acyclovir
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?
<100
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
what is treatment for cryptococcal meningitis?
IV amphotericin B + flucytosine for 2 weeks
add fluconazole PO for 8 weeks
