CNS Infections Flashcards
Why are infections in the cranial cavity so dangerous?
Infection leads to inflammation which in an enclosed space like the skull leads to compression herniation and necrosis.
If you have pyogenic meningitis in a non immunosuppressed patient caused by a gram +ve what is it likely to be?
Streptococci Pneumonia
If you have pyogenic meningitis in a non immunosuppressed patient caused by gram -ve rods what is it likely to be?
Neisseria Meningitidis
If you have pyogenic meningitis in an immunosuppressed patient caused by gram +ve rods what is it likely to be?
Listeria Monocytogene
If you have a pyogenic meningitis in an immunosuppressed patient caused by gram -ve what is it likely to be?
H.Influenzae
Someone presents with pyogenic meningitis what is the treatment?
IV Ceftriaxone 2g
IV Dexamethasone
What organisms would IV Ceftriaxone be effective for?
Pneumococcus
Meningococcal
H.Influenzae
If someone is Penicillin allergic what is the alternative to Ceftriaxone?
Chloramphenicol IV 25mg
When is Listeria considered a suspected cause of meningitis?
Over 60’s
Immunosuppressed diabetes Alcohol
If Listeria is the suspected cause of the meningitis what is the treatment?
IV Ceftriaxone
IV Dexamethasone
IV Amoxicillin 2g 4 hourly
If someone has recently travelled and presents with meningitis what is the treatment?
IV Ceftriaxone
IV Dexamethasone
IV Vancomycin - increased risk of Penicillin resistance
For all cases of Pyogenic Meningitis what is the baseline length of treatment ?
5 days
A Purpuric non blanching rash is only present in one form of meningitis. Which organism is responsible?
Meningocococcal Menigitis
What is the presentation of viral meningitis?
Headache Fever Neck Stiffness
When is a common time for people to contract Viral Meningitis ?
Late Summer Autumn
What are two common causes of viral meningitis ?
Enterovirus
HSV - Most severe infection
What is the treatment for viral meningitis?
Usually supportive due to its self limiting nature.
What is used to diagnose viral meningitis ?
CSF
PCR
What are the clinical signs of encephalitis ?
Confusion
Coma
Behavioural Changes - due to cerebral cortex involved
What signs can show up on MRI that might indicate a encephalitis?
Temporal lobe and adjacent parahippocampal gyrus are bright white on MRI
What gives the definitive diagnosis of encephalitis ?
Lumbar puncture
What are the clinical signs of a CNS infection?
Headache Vomiting Pyrexia Neck Stiffness Photophobia Lethargy Confusion Rash
What nerves are at risk in a very purulent meningitis?
III Oculomotor
VI Abducens
What routes can an infection take to cause a meningitis ?
Direct route - Invasion through bone into the cranial cavity e.g. mastoiditis from middle ear
Remote focus - Endocarditis Myocarditis blood
If there is a suspicion of a raised ICP what should be undertaken before a Lumbar Puncture ?
CT
What region are you trying to hit in a lumbar puncture?
Sub Arachnoid Space
How may vials should be taken and where should they be sent to?
1 Haematology Cell Count and differentiation
2 Microbiology - Gram stain and culture
3 Chemistry - Glucose Protein
4 Haematology - Cell count
What is normal for a CSF sample?
Protein - 0.15 to 0.45
Glucose - 40 to 60% of blood
No RBC
WBC 5mm³
Bacterial Meningitis
WBC >2000mm³
Neutrophils >1180
High Protein >220
Low Glucose
Viral Meningitis
Less WBC
Lymphocytes > Neutrophils
Normal Glucose
Slightly High or normal protein
If someone presents with Neisseria Meningitis what should you do?
Alert Public Health
Close relatives given vaccine or prophylaxis
Where is Neisseria Meningitis found in healthy individuals?
Throat
What is it that causes the most serious symptoms in a Neisseria Meningitis infection?
Endotoxins
What are some of the more severe symptoms due to Neisseria Meningitis?
Non Blanching Rash
Necrosis of the extremities
High Morbidity
What else is required in order diagnose H.Influenzae?
Blood factors are required for cultures
When is a S.Pneumonia infection more likely?
CSF leaking
Skull fractures
Cochlear Implant
What does someone with TB meningitis present like?
Non specific generally ill health
High Morbidity
When is a meningitis considered Aseptic?
No bacteria are found in the lumbar puncture
What does the CSF look like in Aseptic Meningitis?
Low WBC
Normal Glucose
Minimally Elevated protein
Treatment for HSV I and II is what?
Acyclovir
What is one way other than the severity to differentiate between HSV and Enterovirus?
Enterovirus has no confusion
List some non infectious causes of Meningitis?
Sarcoidosis
Carcinoid
