CNS Infections Flashcards
4 reasons why CSF infections are difficult to treat
Low proteins so no compliment activation, low IgG, no lymph, BBB means not all drugs given will get to where you want them
List the main routes of infection into the CSF
Blood borne, parameningeal supppuration, defect in the dura eg surgery, through the cribiform plate
Which two to features of gram +ve and -ve bacteria cause the inflammatory cascade?
\+ve = lipoeichoic -ve = endotoxins
Describe the inflammatory cascade
- Bacteria in blood enters the CSF at the choroid plexus.
- Causes inflammatory mediators to be released
- This attracts Neutrophils which release O- Toxic to the endothelium
- Alters the permeability of the BBB causing oedema
Name some inflammatory mediators
IL-1,6,8
NO
PAF
TNF
Name some virulence factors of bacteria which enable them to get into your blood
IgA protease
Pili
Endocytosis
They can separate tight junctions
Difference in inflammatory cascade in viral and bacterial meningitis
viral - mononuclear
bacteria - neutrophilic
Symptoms of meningitis
Headache, photophobia, nausea, vomiting, neck and back stiffness, rash, kernigs sign (chin on neck)
Name the two types of rash you can acquire
petechial and purpuric
Symptoms of meningitis in an infant
strange cry, convulsions, flaccid , bulging fontanelle, fever, vomiting
What makes diagnosing meningitis difficult
- General symptoms similar to other diseases e.g. sever UTI sub arachnoid haemorrhage
- Symptoms not always all present
Describe the use of a lumbar puncture in diagnosing meningitis (2+1-)
Rapid test
Can distinguish between viral and bacterial
Risk of herniation (dont do if risk of increased ICP_
When would you use a CT scan in investigating meningitis
when diagnosis is in doubt
with focal abnormalities
with coma or seizures as non-urgent
Negatives to using CT scans in investigating meningitis
doesn’t diagnose, takes time, poor predictor of raised ICP
Name 3 more tests you can use to investigate meningitis
Gram stain, PCR, Aggulation tests ( look for antigens)
- Nisseria meningitisis
- Strep pnuemoniae
- Haemophilus influenza B
- B streptococci
- E. Coli
- Listeria monocytogenes
- children and young adults
- children under 2 and elderly
- uncommon (vaccine)
- neonates
- neonates
- neonates / immunocompramised
Name the complications of meningitis
death, subdural collection, cerebral vein thrombus, visual/sensory/motor deficit, convulsions, 10% deafness, hydrocephalus ( increased fluid on brian )
Describe the management of meningitis
antibiotics, oxygenation, anticonvulsants, prevention of hypoglycaemia and hyponatraemia, decrease intracranial pressure
Describe Pneumococcal Meningitis
2nd most common, caused by Strep pnuemoniae. 30 % mortality. can also cause pneumonia and ear infection.
Factors that predispose Pneumococcal meningitis
myeloma, alcohol, diabetes, IMSuppression
Describe some features of Listeriosis Meningitis
Meningo-encephalitus. - effects brain stem so can cause ataxia and movement problems. mortality 20%
Name some of the prevention and controls for Meningitis
Vaccines, Chemoprophylaxis
What is Myelitis
Inflammation of the spinal cord
What is Encephalitis
Inflammation of the brain
Symptoms of Encephalitis
Irritable, altered personality, ataxia, brisk reflexes, brainstem failure = slow pupil reflexes, brain swelling = neurological signs
