CSF AUBF

Functions of CSF

supply nutrients to the nervous system
remove metabolic wastes from CNS
maintain intracranial pressure
produce mechanical barrier to brain and spinal cord

Layers of Meninges

Dura Mater
Arachnoid Mater
Pia Mater

Dura Mater

outermost layer
skull & vertebral canal lining
“hard mother”

Arachnoid mater

inner membrane
spiderweb-like appearance

Pia mater

thin membrane
brain and spinal cord lining (direct)
“gentle”

Subarachnoid space

between arachnoid mater and pia mater
contains CSF

Choroid plexuses of two lumbar ventricles (3rd and 4th)

produce CSF

approx volume of CSF produced per hour

20 ml fluid every hour

CSF volume in adults

90-150 ml

CSF volume in neonates

10-60 ml

to maintain normal range volume

reabsorption of fluid to the blood capillaries in arachnoid granulations

prevent reflux of fluid

arachnoid granulations cells (acts as valves)

capillary wall lining

loosely connected endothelial cells (allows passage of nutrients and wastes)

endothelial cells tight-fitting structure

blood brain barrier

specimen collection

lumbar puncture (between 3rd and 4th lumbar or 4th and 5th lumbar)

volume of CSF that can be removed

depends on the volume available in the patient (adult/neonate) and opening pressure of CSF

elevated pressure during specimen collection

requires slow withdraw of fluid with careful monitoring 

Tube 1

chemical and serological (contaminated w blood/bacteria)

Tube 2

microbiology tests

tube 3

hematology (least likely contaminated, far from tap procedure)

tube 4

back up for microbiology (least contamination)

specimen handling/storage

performed stat, if not possible:

hematology - refrigerated 4 hrs

microbiology - room temp

chemistry & serology - frozen

CSF appearances

crystal clear, cloudy/turbid, milky xanthochromic, hemolyzed/bloody

Significance and Cause:

Crystal clear

normal

Significance and Cause:

hazy/turbid, milky, cloudy

wbc - meningitis

microorganisms - meningitis

protein - blood brain barrier disorder/ IgG production in CNS

Significance and Cause:

oily

radiographic contrast media

Significance and Cause:

bloody

rbcs - hemorrhage or traumatic tap

Significance and Cause:

xanthochromic

hemoglobin - old hemorrhage, lysed cells from traumatic tap

bilirubin - rbc degradation, elevated serum bilirubin

carotene - increased serum level

protein - blood brain barrier disorder

melanin - meningeal melanosarcoma

Significance and Cause:

clotted

protein - blood brain barrier disorder

clotting factors - dues to traumatic tap

Significance and Cause:

pellicle 

protein - blood brain barrier disorder

clotting factors - tubercular meningitis

Traumatic tap vs cerebral hemorrhage:

blood distribution

traumatic tap: uneven blood distribution

cerebral hemorrhage: all tubes are equally bloody

Traumatic tap vs cerebral hemorrhage:

clot formation

traumatic tap: clot

hemorrhage: no fibrinogen = no clotting (diseases w bbb = clotting w/o bloody fluid)

diseases causing clot formation in hemorrhage

meningitis, froin syndrome, blocked CSF circulation in subarachnoid space

web like pellicle

associated with tubercular meningitis

overnight refrigeration of fluid

Traumatic tap vs cerebral hemorrhage:

xanthochromic supernatant

traumatic tap: absent

hemorrhage: present

(2hrs rbc before lysis)

normal intracranial pressure

5-15 mmHg

bilirubin deposits in brain

kernicterus

Traumatic tap vs cerebral hemorrhage:

erythrophages

traumatic tap: none

hemorrhage: present, macrophage with ingested red blood cells.

Traumatic tap vs cerebral hemorrhage:

d-dimer

present in hemorrhage 

protein formed when blood clot dissolve

dilution factor: clear

undiluted

dilution factor: slightly hazy

1:10

dilution factor: hazy

1:20

dilution factor: slightly cloudy

1:100

dilution factor: cloudy/ slightly bloody

1:200

dilution factor: bloody/turbid

1:10,000

WBC normal values in CSF

adult: 0-5 WBC/μL

neonates: 0-30 mononuclear cells/μL

agranulocyte dominant

diluting fluid

3% acetic acid with methylene blue