CNS infections and meningitis Flashcards

1
Q

What are the 4 lobes of the brain?

A

Frontal
Temporal
Parietal
Occipital

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2
Q

How many spinal nerves are there?

A

31 pairs

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3
Q

What are the 4 routes of entry?

A
Haematogenous spread (e.g. pneumococcus, meningococcus)
Direct implantation (e.g. trauma)
Local extension (e.g. from the ear)
PNS to CNS (e.g. rabies)
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4
Q

What are the meningeal layers

A

Dura - Outermost
Arachnoid
Pia (Innermost)

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5
Q

What is meningitis usually caused by?

A

Bacteria such as Neisseria meningitis, strep pneumo, TB, Haem influ

Fungus such as cryptococcus neoformans

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6
Q

What can encephalitis be caused by?

A

Viruses such as rabies, arboviruses

amoeba

Parasites

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7
Q

What can myelitis be caused by?

A

Spinal cord infections due to polio

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8
Q

What can neurotoxins like Clostridium tetani and clostridium botulinum cause?

A

Rigid paralyisis and flaccid paralysis respectively

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9
Q

Difference between meningitis and meningoencephalitis?

A

Meningoencephalitis is the inflammation of the meninges AND brain parenchyma

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10
Q

What can meningitis be classified into?

A

Acute - Bacterial (Meningococcal, Neiseria, H.influenzae, GBS, E Coli, Listeria)
Chronic - TB, spirochetes, crytpococcus
Aseptic - Viral

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11
Q

Where can Listeria be found?

A

Blue cheese, mayo

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12
Q

Babies being delivered via vaginal delivery are in bigger risk of developing which kind of meningitis?

A

GBS and E Coli

So if mum is positive for GBS, give Benzylpenicilin during delivery

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13
Q

What is a tell tale sign for meningococcal meningitis?

A

Purpural petichael rashes due to thrombocytopaenia as your platelet count drops. Rashes are non blanching.

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14
Q

How can meningococcal meningitis present?

A

Thrombocytopaenia

Septicaemia - Hypovolaemia, coagulopathy, metab acidosis, myocardial failure

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15
Q

What can be seen in a CT head of someone with TB meningitis?

A

Dilation of ventricles
Thick wall abscess
Space occupying lesions

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16
Q

What are the symptoms of aseptic meningitis?

A

Headache, stiff neck and photophobia

May have non specific rash

17
Q

What are the biggest viral causes of meningitis

A

Enterovirus - Cocksackie A and B, echovirus, polio

Herpes - 1 and 2

18
Q

What is encephalitis

A

Infection of brain parenchyma - Mostly due to virus

19
Q

How do viral infections spread to cause encephalitis?

A

Mosquitoes
Lice
Ticks

Person to person

20
Q

What is the international leading cause of encephalitis?

A

West Nile virus

21
Q

What are the other leading causes of encephalitis?

A

Herpes
Enterovirus

Bacteria - Listeria

Amoeba

Toxoplasmosis

22
Q

How can you visualise brain abscess or infarcts?

A

MRI not CT

23
Q

What organisms mostly cause brain abscess?

A

Strep

Staph

24
Q

How to investigate CNS infections?

A

CSF sample
Blood culture
Throat swab
Blood PCR to detect pneumococcla and meningococcal DNA

25
Q

What should the CSF studies of a normal person look like?

A
Clear fluid 
0-5 leukocytes 
No gram stain
0.15-0.4 protein 
>60% blood glucose levels
26
Q

What should the CSF studies of a person with purulent meningitis look like?

A
Turbid fluid 
100 - 10 000 Polymorphs
\+ve gram stain
0.5 - 4 protein 
<60% blood glucose levels
27
Q

What should the CSF studies of a person with aseptic meningitis look like?

A
Clear or slightly turbid fluid 
15 - 1000 Polymorphs
Negative gram stain
0.5 - 1 protein 
>60% blood glucose levels
28
Q

What should the CSF studies of a person with TB meningitis look like?

A
Clear or slightly turbid fluid 
30 - 1000 Polymorphs
Negative gram stain - Scanty acid fast bacilli 
1 - 6 protein 
<60% blood glucose levels
29
Q

What do stains look like in general.

A

Purple - Gram +ve
Pink - Gram -ve

Cocci - spherical
Rods - Cuboidal

30
Q

What is a gram +ve diplococci in CSF?`

A

Pneumococcos

Strep pneumo

31
Q

What shape and gram stain in Listeria?

A

Gram +ve

Rod

32
Q

What is a gram -ve dipolococci

A

Neisseria

33
Q

What is a gram +ve cocci in clusters

A

Staph

34
Q

What is a gram +ve cocci in chains or pairs

A

Strep

35
Q

What is a gram +ve rod

A

Listeria

36
Q

What is a Ziel Nielson stain used for?

A

TB

37
Q

High pressure CSF meningitis?

A

Crytococcus

Usually seen in HIV patients

38
Q

How to treat meningitis?

A

Ceftriaxone 2g iv bd

If they are older than 50 or immunocompromised or you suspect Listeria, add Amoxicillin 2g iv 4 hourly

39
Q

How to treat meningo-encephalitis?

A

Ceftriaxone 2g iv bd

If they are older than 50 or immunocompromised or you suspect Listeria, add Amoxicillin 2g iv 4 hourly

Also give Acyclovir 10mg/kg iv tds as viruses are the leading cause of encephalitis