Flashcards in Lecture 6: CSF and CNS Infections Deck (20):
Where is CSF produced and reabsorbed?
Produced by Choroid plexus of ventricles
Reabsorbed by arachnoid granulations through the process of transcytosis
500 ml/day of adults (water bottle’s worth)
90-150 ml in adults
What is the choroid plexus?
Epithelial cells that are specialized ependymal cells
What is the difference between CSF and plasma?
The CSF has
LESS proteins/amino acids
LESS ion concentration except for Cl- and Mg2+ (around same for Na)
What are the 4 physiologic roles of CSF?
1. Physical Support
2. Protection (protection in sense of maintaining composition of microenvironemt)
3. Extracellular Homeostasis
4. Excretory Waste Function
What are the three features of brain capillaries that contribute to formation of blood brain barrier?
1. tight junctions between non-fenestrated capillary endothelial cells
2. thick basement membrane
3. astrocyte endfoot
What are the delineating lab findings of bacterial meningitis?
High WBC count (over 1000 cells/ul)
DECREASE in glucose
HUGE increase in protein
What are the delineating lab findings of viral meningitis?
Normal opening pressure
Lymphocytes for cell differential
What is delineating lab findings of fungal meningitis?
Same WBC count as viral meningitis (10-200 cells/ul)
What are the classic presenting symptoms for meningitis?
2. stiff neck
Fever, headache, altered mental status
What causes bacterial meningitis is neonates (0-6months)?
1. Listeria monocytogenes
2. E. coli
3. Group B streptococcus
What causes bacterial meningitis in children and adults (6mo – 60 years)
1. Streptococcus pneumoniae
2. Neisseria meningitides
3. Haemopilus influenza
What causes bacterial meningitis in adult and immunosuppressed patients (over 60 years)?
1. Streptococcus pneumonia
2. Listeria monocytogenes
What are the three classes of viruses that cause viral meningitis?
-most common cause of viral meningitis in summer/fall and commonly occur in children
2. Herpes virus
HSV1 = encephalitis
HSV2 = meningitis
Greater moribidity and mortality though less common
Spread by mosquitoes and ticks
e.g. west nile, st. Louis encephalitis virus
What are the 3 fungi that cause HIV associated meningitis?
1. Cryptococcosis neoformans
2. Coccidioides immitis (Valley Fever aka coccidiodomycosis)
3. Histoplasma capsulatum (Cave Disease)
What are the 3 bacteria that cause HIV associated meningitis?
1. Listeria monocytogenes
2. Mycobacterium tuberculosis
3. Treponema pallidum (Syphillis)
What are the two viruses that cause HIV associated meningitis?
What are the HIV associated meningitis?
-coccidiodes immitis (valley fever)
-histpolasma capsulatum (cave disease)
-Group B strep?
-Treponema pallidum (syphilis)
What are the mechanisms through which infectious agents enter CNS?
1. bacterial surface proteins attach to endothelial cells and migrate transcellularly
-lipoteichoic acid in streptococcus pneumonia appears to utilize an endogenous receptor for platelet activating factor to enter CNS
2. Trojan horse mechanism
-cross barriers inside a circulating cell (monocyte)
3. Physically disrupted barriers
What are the pathologic processes that can cause fluid to appear?
-increased WBC due to CNS infection
ORANGE = carotene ingestion
BROWN = metastatic melanoma
Metastatic mucinous adenocarcinoma