Infections of CNS Flashcards
what area of the CNS is infection during Encephalitis ?
inflammation / infection of brain substance
what area of the CNS is infection during Meningitis ?
inflammation / infection of meninges
what area of the CNS is infection during Myelitis ?
inflammation / infection of spinal cord
what is the classical triad of meningitis ?
fever
neck stiffness
altered mental state
what the of rash do people get during a meningitis ?
Petechial skin rash
what test is done to test for the petechial skin rash?
tumbler test
- non blanching
what type of meningitis is the petechial rash commonly seen?
the bacteria meningitis
as well as the classical triad of symptoms, what other symptoms can be seen during meningitis ?
confusion declining consciousness cranial nerve palsy seizures focal symptoms
what are the four main categories of aetiology for meningitis ?
infective
inflammatory
drug induced
malignant
what drugs can induce meningitis ?
NSAIDs and IVIG (Intravenous Immunoglobulin)
what are the three infective agents that can cause meningitis ?
bacterial
viral
fungal
what group of people usually are infected by fungal meningitis ?
immunosuppressed people
what is the virus that causes viral meningitis ?
enteroviruses
what two bacteria can cause bacterial meningitis ?
Neisseria meningitidis (meningococcus) Streptococcus pneumoniae (pneumococcus)
what are the symptoms of meningitis ?
fever headache neck stiffness petechial skin rash confusion
what are the symptoms of encephalitis ?
flu like stage in first couple of weeks
confusion
abnormal behaviour
seizures
focal symptoms (vision, hearing)
is the onset of viral encephalitis faster or slower than bacterial meningitis ?
viral encephalitis is slower
is cerebral dysfunction more prominent in viral encephalitis or bacterial meningitis ?
viral encephalitis
what are the four main categories of the aetiology of encephalitis ?
infective
inflammatory
metabolic
malignant
what is an inflammatory cause of encephalitis ?
limbic encephalitis
what is the most common infective cause of encephalitis ?
herpes simplex virus
what three metabolic problems could cause encephalitis ?
hepatic
uraemia
hyperglycaemic
what are the two antibodies that can cause autoimmune encephalitis ?
anti - VGKC (voltage dated K channels)
anti - NMDA
what are the clinical signs of anti-VGKC encephalitis ?
frequent seizures
amnesia
altered mental state
what are the clinical signs of anti-NMDA encephalitis ?
flu like stage
prominent psychiatric features
altered mental state
result in coma
what investigations would be done for meningitis ?
blood cultures
lumbar puncture
should the blood tests and lumbar puncture be done as soon as possible?
yes
- they want to be done before antibiotics have started to be given
when should a CT scan be done for meningitis ?
if there is a contraindication for lumbar puncture
what are the investigations that should be done for encephalitis ?
blood cultures
imaging (CT/MRI)
lumbar puncture
EEG
what two tests can be done on the CSF from a lumbar puncture ?
CSF microscopy
CSF culture
what are some contraindications for lumbar puncture ?
papilloedema GCS <10 severe immunocompromised new onset seizures focal neurological deficit
what does focal symptoms suggest about the brain?
suggest a focal brain mass/tumour
what does reduced conscious level suggest?
raised intracranial pressure
is the opening pressure of the CSF increased, decreased or normal with bacterial meningitis ?
increased
is the opening pressure of the CSF increased, decreased or normal with viral meningitis or encephalitis ?
normal/increased
what WBC is high in CSF of bacterial meningitis?
neutrophils
what WBC is high in CSF of viral meningitis/ encephalitis ?
lymphocytes
is glucose levels in CSF increased, decreased or normal with bacterial meningitis?
decreased
- sometimes zero
is glucose levels in CSF increased, decreased or normal with viral meningitis/ encephalitis ?
normal
is protein levels in CSF increased, decreased or normal with bacterial meningitis?
high
is protein levels in CSF increased, decreased or normal with viral meningitis/ encephalitis ?
slightly increased
what type and shape of bacteria causes bacterial meningitis ?
gram positive cocci in chains
what is the commonest cause of encephalitis in europe ?
herpes simplex virus
should treatment of encephalitis be started on suspicion ?
yes
- even if the lumbar puncture results aren’t back yet
what is the mortality of herpes simplex encephalitis ?
70%
what antibiotic should be started for herpes simplex virus?
aciclovir
are HSV encephalitis and bacterial meningitis easy to treat in the early stages ?
yes
how many types of HSV are there?
two types
- type 1 and 2
once someone is infected with herpes group of viruses can they be cured?
no they are always infected
where abouts does the herpes virus lie latent to cause cold sores and genital herpes ?
trigeminal and sacral ganglion
what type of herpes simplex virus causes encephalitis ?
type 1
are enteroviruses DNA or RNA viruses ?
RNA
how are enteroviruses spread?
faecal oral route
do enteroviruses cause GI symptoms ?
no
what part of the history is very important to ask about when talking about CNS infections ?
travel history
sexual history
how are arbovirus encephalitides transmitted ?
by a vector such as a mosquito or ticks
give some examples of arbovirus encephalitides?
West Nile virus St Louis Encephalitis Western Equine Encephalitis Tick Borne Encephalitis Japanese B Encephalitis
what is an important factor when thinking about uncommon infections from other countries ?
immigration
what is a brain abscess?
localised area of pus within the brain
what is a sub dural empyema ?
thin layer of pus between the dura and arachnoid membranes over the surface of the brain
what symptoms can be caused by a brain abscess?
increased intracranial pressure
decreased conscious level
focal symptoms dependant on the area of brain affected
what are the clinical symptoms of a brain abscess?
fever headache seizures hemiparesis decreased conscious level
what are three underlying causes of a brain abscess?
poor dentition
sinusitis
(middle) ear infection
what are two differential diagnoses of a brain abscess or empyema ?
subdural haematoma focal lesson (tumour)
what are some causes of a brain abscess?
penetrating head injury
spread of infection from adjacent structures
blood borne infection
post surgery
what investigations should be done for a brain abscess?
CT/ MRI
examination of head/neck
blood cultures
biopsy (drainage of pus)
is drainage of a abscess always possible?
no
- if the abscess was in the brain stem then the risks of damage would not be worth it
what type and group of bacteria are usually found in brain abscesses?
streptococci bacteria
- strep milleri group
what group of antibiotics are the strep milleri group of bacteria found in brain abscesses sensitive to?
penicillin
what percentage of brain abscesses contain strepococci bacteria ?
70%
what are three bacteria in the strep milleri group?
Strep anginosus,
Strep intermedius,
Strep constellatus
what antibiotics should be given to aerobic bacteria in brain abscesses?
Penicillin or ceftriaxone
is strep bacteria aerobic or anaerobic ?
aerobic
what antibiotic should be given to anaerobic bacteria in brain abscesses?
metronidazole
why are antibiotics sometimes not effective for brain abscesses?
sometimes the antibiotic can’t penetrate the abscess properly so high doses are required for penetration
what system in the brain reduces the effect of drugs on the brain ?
blood brain barrier
with which conditions should the patient be offered a HIV test?
Cerebral toxoplasmosis Aseptic meningitis /encephalitis Primary cerebral lymphoma Cerebral abscess Cryptococcal meningitis Space occupying lesion of unknown cause Dementia Leucoencephalopathy
what brain infections are common in HIV patients with low CD4 counts ?
Cryptococcus neoformans Toxoplasma gondii Progressive multifocal leukoencephalopathy (PML) Cytomegalovirus (CMV) HIV-encephalopathy
are PCR tests specific ?
yes very specific
what tests should be done to investigate infections associated with HIV?
India Ink Toxoplasmosis serology (IgG) JC virus PCR CMV PCR HIV PCR
what bacterial antigen is detected using the india ink test?
cryptococcal antigen
what type of organism is cryptococcal ?
fungi
what is the transmission route for fungi?
inhalation from dust
form what object do immunocompromised people in aberdeen commonly get a fungal brain infection?
opening brown bins full of compost
what bacteria causes lyme disease ?
Borrelia burgorferi
what bacteria causes syphilis ?
Trepomena pallidum
what bacteria causes leptospirosis ?
Leptospira interrogans
how many stages are there for lames disease?
3
how is lyme disease transmitted?
vector borne
- ticks
what type of rash is seen in stage 1 lyme disease ?
erythema migrans
where is the erythema migrans rash seen on the patient ?
where the tick bite was
what type of symptoms are seen in stage 1 lyme disease ?
flu like symptoms
- fatigue
- headache
- fever
- chills
- neck stiffness
how long does stage 1 lyme disease last for ?
1 month
how does the bacteria form the tick spread around the body after the initial bite?
blood and lymphatics
what are the common symptoms in stage 2 lyme disease ?
joint and muscle pain
neurological involvement
during lyme disease, is the PNS or CNS more effected ?
PNS
how long does stage 2 lyme disease last for?
weeks - months
how long does stage 3 of lyme disease last for?
months - years
does lyme disease cause chronic fatigue syndrome ?
no
what two conditions of neurological involvement is seen in stage 3 lyme disease
Subacute encephalopathy
Encephalomyelitis
what investigations should be done for lyme disease ?
serology CSF lymphocytosis PCR of CSF MRI spine and brain nerve conducting studies
what is the treatment for stage 1 and 2 lyme disease
oral doxycycline
what is the treatment for stage 3 lyme disease ?
1 month IV ceftriaxone
how many stages of presentations are there for syphilis ?
3
what is syphilis treated with?
high dose penicillin
what blood tests can be done for syphilis ?
Treponema specific and non-treponemal specific (VDRL) antibody tests
what type of virus is poliovirus ?
enteroviruses
what symptoms does polio cause ?
flaccid paralysis
- no sensory features
what can the polio vaccine be given ?
injection
orally
what part of the nervous system does the polio virus affect?
anterior horn cells of lower motor neurones
how is rabies transmitted to humans ?
bite
saliva
what part of the nervous system does the rabies virus affect?
infects the peripheral nerves and migrates to CNS
what are the clinical symptoms of rabies ?
ascending paralysis and encephalitis
how is the rabies infection managed ?
sedation
intensive care
death
what mammals commonly transmit the rabies virus ?
dogs and bats
in what form is the rabies virus given in the vaccine ?
killed vaccine
who should be given the rabies vaccine?
people travelling abroad to areas where rabies incidence is high
bat handlers
regular handlers of imported animal s
what are the three steps of suspected rabies from a dog bite ?
- wash wound
- give active rabies immunisation
- give human rabies immunoglobulin
what type of bacteria is clostridium tetani?
anaerobic gram positive bacillus, spore forming
where about does the toxin of tetanus act in the nervous system ?
acts at the NMJ
what are the clinical symptoms of tetanus?
rigidity
spasm
risus sardonicus
what is risus sardonicus ?
highly characteristic, abnormal, sustained spasm of the facial muscles that appears to produce grinning
What two medications should be given to suspected tetanus patients ?
penicillin
immunoglobulin
what bacteria causes botulism ?
clostridium botulinum
what type of bacteria is clostridium botulinum ?
Anaerobic spore producing gram positive bacillus
What are the three routes of infection of botulism ?
infant intestinal colonisation
food borne
wound - common in drug users
why are drug users high risk for botulism ?
when they inject the drugs, if they miss the vein then the drugs can cause an abscess to form and the bacteria to colonise
what are the common clinical signs of botulism ?
pupil dilation
descending symmetrical flaccid paralysis
does botulism affect the sensory and motor fibres ?
just the motor fibres
how is botulism diagnosed ?
culture from debrided wound
nerve conduction study
what are the three treatment options for botulism ?
- anti-toxin (A,B,E)
- penicillin/ metronidazole (prolonged treatment)
- radical wound debridement
state two post infective inflammatory syndrome which can occur after an infection?
- CNS
- PNS
CNS
- Acute disseminated encephalomyelitis (ADEM)
PNS
- Guillain Barre Syndrome (GBS)
what type of condition is post infective inflammatory syndrome?
autoimmune
state some symptoms of Guillain Barre Syndrome (GBS)?
pain, tingling and numbness
progressive muscle weakness
co-ordination problems and unsteadiness
what is the most common cause of CJD ?
sporadic CJD
is CJD disease common?
no very rare
1 per million
is the presentation of sporadic CJD all the same ?
no it varies
what age range is CJD most common?
> 60yrs
what substance causes CJD ?
Transmissible Proteinaceous particle – Prion
what symptoms would someone with CJD experience ?
myoclonus (jerks) weakness hyper reflexia blindness seizures confusion tremor
what disease should be considered in someone over 60yrs who has rapidly progressive dementia ?
sporadic CJD
what is the prognosis and survival time for sporadic CJD?
- poor due to rapid progression
- death within 6 months
what are some differential diagnoses of sporadic CJD?
Alzheimers with myoclonus Subacute sclerosing panencephalitis (SSPE) CNS vasculitis Non-convulsive status Inflammatory encephalopathies
what three investigations should be done to test for CJD?
MRI
EEG
Lumbar puncture
for CJD infection will the protein in the CSF be normal ?
normal or raised
what would be seen on a MRI with a patient who has variant CJD?
pulvinar sign
what age range is at most risk for new variant CJD?
younger onset <40yrs
what is a common way for people to become infected with new variant CJD?
eating infected meat
does new variant or sporadic CJD have a longer course and therefore less severe?
new variant has a longer course
is Guillain Barr syndrome anaerobic or aerobic infection ?
aerobic
which infection would have flu like symptoms before neurological signs ?
viral encephalitis
lymes disease
should antibiotics be started while waiting for a CT and a lumbar puncture for viral encephalitis ?
yes
what infection are drug users high risk for contracting ?
botulism
what rash is seen during lymes disease ?
erythema migrans
what virus is the most common cause for viral encephalitis ?
herpes simplex
what group of bacteria is most common in brain abscesses?
strep milleri
can poliomyelitis be vaccinated against ?
yes
does bacterial meningitis increase CSF opening pressure?
yes
does viral encephalitis increase CSF opening pressure?
no
