Bacterial meningitis Flashcards
MENINGES
Protective coverings of the brain and spinal cord
Dura mater
Tough and strong
Two layers: one to skull, and other to arachnoid
Arachnoid mater
Spider like.
Where CSF circulates
Pia mater
Delicate.
Adheres to brain surface (gyri and sulci)
What is meningitis
Inflammation of the Meningie.
Specifically in Pia mater, arachnoid, and CSF subarachnoid
Common cause of meningitis
Bacterial (purulent)
Viral (lymphocytic)
Most at risk of meningitis
Children under 5
Bacterial meningitis
Common cause: streptococcus pneumoniae, NEISERRIA MENINGITIDIS
Where are bacterial meningitis found
Nasal passages; coughing sneezing, respiratory secretions
Risk factor Bacterial Meningitis
Neurosurgery Head trauma Immunocompromised Ear infection Sinusitis
Diagnosis of Bacterial meningitis
CSF cloudy and purulent. Increased pressure. Contains large number of neutrophils. Increased protein. Reduced sugar as eaten up by bacteria.
Colour of CSFLP when positive of bact. meningitis
Cloudy and purulent.
Pathophysiology of Bact. Meningitis.
- Bacteria in CSF.
- Release of inflammatory response (neutrophils).
- Blood brain barrier becomes leaky and allows albumin to enter brain as it pulls water with it.
- Leads to cerebral oedema - increased fluid in brain = increased pressure.
- Pathogens enter Subarachnoid space - further exacerbate inflammatory response.
- Vascular congestion > engorged swollen veins and purulent exudate.
- Blockage/collapse of arterioles (ischaemia + infarction).
- Thickening of meninges = dysfunction of a cranial nerve.
- Can impair outflow of CSF = Hydrocephalus.
Complication of Bacterial: Hydrocephalus
Enlargement of CSF within brain.
Abnormal increase in CSF volume.
Complication of Bacterial: Cerebral oedema
Increased fluid = increased pressure in brain.
Disrupted BBB > albumin moves into brain > water follows > increased fluid > increased brain volume > increased ICP.
