CNS infections Flashcards by Maria Keriakos

How does N. meningitidis appear on gram stain?

Gram negative diplococcus

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what is the common type of pathogen to cause encephalitis?

viral

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what is encephalopathy?

reduced level of consciousness/ diffuse disease of brain substance, usually non-infective

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What is a neutopathy?

damage to peripheral n erves cuasing wekaness or numbness

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what is mononeuritis multiplex?

inflammation and damage to 2 or more individual nerves, usually causing pain and/or loss of function
can be caused by HIV, leprosy, Lyme’s disease and Hep A

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what is polyradiculopathy?

damage to multiple nerve roots (e.g. cauda equina)

can be cuased by HIV, CMV, syphilis, HSV

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what is myelitis?

inflammation of the spinal cord

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what is Meningoencephalitis?

resembles both Meningitis and encephalitis (inﬂammation of the brain and the meninges)

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what are the symptoms of meningitis?

fever
worsening headache
photophobia neck stiffness
rash commonly seen with N. meningitidis

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what are the signs of menigism?

fever
worsening headache neck stiffness
papilloedeama Kernig’s sign
Brudzinski’s sign

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what is Kernig’s sign?

lay pt supine
bend leg so thigh is 90˚ to waist
try to straighten the lower leg - unable to straighten leg greater than 135˚ without pain - this test stretches the meninges

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what is Brudzinski’s sign?

flex the neck of the pt - the sign is that the pt’s hips and knees will flex to reduce the stretch on the meninges

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how does papillodema look like on fundoscopy when it is due to menigitis?

bilateral
disc margin disappears
can occur over hours to weeks

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How is meningitis managed?

Blood cultures before lumbar puncture
start antibiotics
FBC - to check the WCC and platelet count before lumbar puncture
U&E - baseline kidney function be fore starting antibiotics
CRP
serum Glucose - to compare to the CSF glucose
lactate
Lumbar puncture
CT Head - for signs of raised ICP
Throat swabs (bacterial and viral)
Pneumococcal and Meningococcal serum PCR

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If a pt has raised ICP, when is their headache worse?

on sitting forward or bending

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How is an LP done?

ask the pt to lie on their left side
flex knees to widen the gap between the lumbar vertebrae
use the superior ileac spine as a marker for L4
choose the L3/4 or L4/5 disc space
need goes THROUGH the dura (epidural does not go through the dura mater)

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what layers would you go through when taking an LP?

skin
fascia
spupraspinous ligament 
interspinous ligament 
ligamentum flavum
eipdural space 
dura mater 
arachnoid mater 
so smaple from the sub-arachnoid space where CSF is

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what is the name to the equipment used to measure the opening pressure in LP?

manometer

normal opening pressure is 8-15 mm Hg

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what are the adverse effects of an LP?

Headache
Paresthesia - tingling/numbness around the legs 
CSF leak
Damage to spinal cord
Cerebral herniation and death

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what type of consent is needed for an LP?

written consent

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what advise is given for a post-LP headache?

lay down flat for several hours

drink plenty of fluids

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when should a CT be done before LP?

Age more than 60 - due to increased risk of space-occupying lesions Immunocompromised History of CNS disease New onset/recent seizures
Decreased/-‐ing conscious level
- GCS <14
Focal neurological signs Papilloedema
Atypical history - that is not entirely indicative of meningitis

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how much CSF is needed from an LP?

5ml

10-15 drops per bottle

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what is done with the CSF obtained from LP?

CSF protein
CSF glucose 
microscopy, culture and sensitivity 
viral PCR - for enterovirus, HSV and VZV
bacterial PCR

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when is more than 5ml CSF needed?

to test for TB - so 10 ml is needed

should antibitoics be given before or after a CT head or LP?

do not delay antibiotics whilst waiting for the CT head | if you can't do an LP within 30 mins of arrival then give empirical antibiotics

does a raised opening pressure mean a raised ICP?

not necessarily

what are the CSF results for a bacterial cause?

``` raised opening pressure cloudy CSF high cells - neutrophils low CSF:plasma glucose high protein ```

what are the CSF results for a viral infection?

``` normal/raised opening pressure clear CSF high cells - lymphocytes normal CSF:plasma glucose normal/high protein ```

what are the CSF results for TB meningitis?

``` raised opening pressure cloudy/yellow CSF slight increase in cells - lymphocytes low CSF:plasma glucose high protein ```

what are the CSF results for fungal meningitis?

raised opening pressure cloudy/yellow CSF normal/high cells - lympohocytes normal/high protein

what are the CSF results for subarachnoid haemorrhage?

``` riased opening pressure blood stained CSF = XANTHOCHROMIA slight increase in cells normal CSF:plasma glucose high protein ```

what are the risk factors for Listeria meningitis?

``` immunocompromised pregnancy diabetes chronic alcoholics age >60 ```

what bacteria cause meningitis in neonates and what is their appearance on gram film?

E.coli = Gram negative bacilli Group B streptococci = Gram positive coccus Listeria monocytogenes = Gram positive bacilli

what are the bacterial causes of meningitis in children and adults and what is their appearance on a gram film?

Neisseria meningitidis = Gram negative diplococcus Streptococcus pneumoniae = Gram positive diplococcus Haemophilus inﬂuenzae = Gram negative coccobacilli

how is suspected bacterial meningitis managed?

IV Cefotaxime - ADD IV amoxicillin if Listeria - ADD dexamethasone for Pneumococal menigitis consider vancomycin in returning travellers

Why is IV Cefotaxime particularly good (and better then IV amoxicillin for strep) in meningitis?

reliable BBB penetration

how is meningococcal meningitis prevented?

Meningitis vaccine Men B given at 8 weeks, 16 weeks and booster at 1 year Men C at 1 year Men ACWY given at age 14

what prophylaxis is given to contacts of a pt with meningococcal meningitis?

ciprofloxacin - 500mg stat on tablet (can be given in pregnancy) rifampicin - 600mg BD for 2 days (cannot be given in pregnancy)

which infection is notifiable?

Meningococcal meningitis

describe the meningococcal rash

petechial/non-blanching

is LP needed in meningococcal sepsis/meningococcal meningitis if a rash is present?

no - not necessary

what is the mechanism of death in those with meningocococal speticaemia?

cardiovascular disease

what is the mechanism of death in those with meningocococal meningitis?

raised ICP

is there a rash in viral meningitis?

what treatment is given for viral meningitis?

supportive - no specific treatment

What is the most common cause of viral meningitis?

enterovirus

How dies enterovirus meningitis present?

child has flu-like illness, sore throat, diarrhoea and the parent presents with meningitis

Is there risk of raised ICP with viral meningitis?

how does encephalitis present?

``` headache fever lethargy new onset confusion decreased GCS no focal neurology no meningism progression to focal signs, seizure, coma ```

which part of the brain is affected most in herpes simplex encephalitis?

fronto-temporal

what investigations are done for encephalitis?

CT head LP can do an EEG

what does the LP show in encephalitis?

``` lymphocytes raised protein normal glucose no organism seen on gram film viral CSF PCR shows virus ```

How is HSV encephalitis treated?

10mg/kg IV aciclovir for 14 days

what is CJD caused by?

prions

what is rabies caused by?

RNA virus

how is rabies transmitted?

saliva spreads to CNS via peripheral nerves replicates in the brain and then spreads to the salivary glands

how is rabies prevented?

vaccine - given to travellers going to endemic areas eg India

what are the symptoms of rabies?

``` fever anxiety confusion hydrophobia hyperactivity/uncontrollable excitement hallucinations violent movement ```

what are the neurological manifestations of HIV?

``` HIV associated dementia viruses: HSV, CMV, progressive multifocal leukoencephalopathy due to the JC virus fungus: cryptococcal meningitis parasitic infection: toxoplasmosis lymphoma neurosyphilis ```

What organism causes tetanus?

Clostridium tetani

what would be seen on gram stain of Clostridium tetani?

Gram positive bacillus | has terminal spores

How does Clostridium tetani cause disease?

``` soil organism spore forming secretes a toxin - tetanospasmin infects dirty wounds toxin released in the wound translocates via peripheral nerve ```

what are the symptoms of tetanus?

onset 7 days Paraesthesia of wound Trismus (lockjaw) Sustained muscle contraction (opisthotonus) Involvement of facial muscles (risus sardonicus- abnormal, sustained spasm of the facial muscles that appears to produce grinning.) Paroxysmal generalised spasms autonomic dysfunction - pain and temperature sensation