This document provides information on cerebrospinal fluid (CSF) including its normal composition and function. CSF is produced by the choroid plexus and circulates in the ventricles and subarachnoid space. It acts as a cushion and transport medium and is absorbed by arachnoid villi. A lumbar puncture, or spinal tap, is performed to collect CSF for analysis to diagnose conditions like meningitis, tumors, or other brain and spinal disorders.

2.  Normal CSF:
› Clear, colorless, and odorless
› CSF fills ventricles and subarachnoid space.
 Composition and formation
› Adult volume 90-150 mL
› Neonate volume 10-60 mL
 Rate of production:
› 550 ml/day, it turns 3.7 times/day.

3.  Lumbar CSF pressure:
› 70-180 mm CSF
 Absorption of CSF occurs by bulk flow is
proportionate to CSF pressure.:
 At pressure of 112 mm (normal average): filtration
and absorption are equal.
 Below pressure of 68 mm CSF, absorption stops.

4.  CSF is formed in:
 Choroid plexus.
 Around blood vessels.
 Along ventricular walls.
 CSF is absorbed by:
› Arachnoid villi

5.  Shock absorber
 A mechanical buffer
 Act as cushion between the brain and cranium
 Act as a reservoir and regulates the contents of the
cranium
 Serves as a medium for nutritional exchange in CNS
 Transport hormones and hormone releasing factors
 Removes the metabolic waste products through
absorption

6.  Normal CSF:
 Clear, colorless, and odorless
Area Appearance Pressure Cells Protein Miscellaneous
Lumbar Clear/colorless 70-180
0-5
(lymphocytes)
<50 mg/dl
Glucose
50-75 mg/dl
Ventricular Clear/colorless 70-190
0-5
(lymphocytes)
5-15 mg/dl

11.  Blood Brain Barrier
› Essential to protect the brain
› Blocks chemicals, harmful substances
› Antibodies and medications also blocked
› Tests for those substances normally blocked can
indicate level of disruption by diseases: ie
meningitis and multiple sclerosis.

12.  Four major categories of disease
› Meningeal infections
› Subarachnoid hemorrhage
› CNS malignancy
› Demyelinating disease

13.  Indications for analysis
› To confirm diagnosis of meningitis
› Evaluate for intracranial hemorrhage
› Diagnose malignancies, leukemia
› Investigate central nervous system disorders

14. • Specimen collection and handling
› Tube 1 – chemistries and serology
› Tube 2 – microbiology cultures
› Tube 3 – hematology
› Testing considered STAT
• Specimen potentially infectious
› If immediate processing not possible
 Tube 1 (chem-sero) frozen
 Tube 2 (micro) room temp
 Tube 3 (hemo) refrigerated

15.  Increased inflammatory cells [pleocytosis] may be
caused by infectious and noninfectious processes.
 Polymorphonuclear pleocytosis indicates acute
meningitis.
 Mononuclear cells are seen in viral infections
(meningoencephalitis, aseptic meningitis), syphilis,
neuroborreliosis, tuberculous meningitis, multiple
sclerosis, brain abscess and brain tumors.

16.  Increased protein: CSF protein may rise to 500 mg/dl
in bacterial meningitis.
 A more moderate increase (150-200 mg/dl) occurs in
inflammatory diseases of meninges (meningitis,
encephalitis), intracranial tumors, subarachnoid
hemorrhage, and cerebral infarction.
 A more severe increase occurs in the Guillain-Barrc
syndrome and acoustic and spinal schwannoma.

17.  Multiple sclerosis:
 CSF protein is normal or mildly increased.
 Increased IgG in CSF, but not in serum [IgG/albumin
index normally 10:1].
 90% of MS patients have oligoclonal IgG bands in CSF.
 CSF in MS often contains myelin fragments and
myelin basic protein (MBP).
 MBP can be detected by radioimmunoassay.
 MBP is not specific for MS.
 It can appear in any condition causing brain necrosis,
including infarcts.

18.  This condition is seen in suppurative tuberculosis
 Fungal infections
 Sarcoidosis
 Meningeal dissemination of tumors.
 Glucose is consumed by leukocytes and tumor cells.

19.  Blood may be spilled into the CSF by accidental puncture of a
leptomeningeal vein during entry of the LP needle.
 Such blood, stains the fluid that is drawn initially & clears
gradually.
 If it does not clear, blood indicates subarachnoid hemorrhage.
 Erythrocytes from subarachnoid hemorrhage are cleared in 3
to 7 days.
 A few neutrophils and mononuclear cells may also be present
as a result of meningeal irritation.

20.  Xanthochromia [blonde color] of the CSF following
subarachnoid hemorrhage is due to oxyhemoglobin
which appears in 4 to 6 hours and bilirubin which
appears in two days.
 Xanthochromia may also be seen with hemorrhagic
infarcts, brain tumors, and jaundice.

21.  Tumor cells indicate dissemination of metastatic or
primary brain tumors in the subarachnoid space.
 Most common among the latter is medulloblastoma.
 They can be detected by cytological examination.
 A mononuclear inflammatory reaction is often seen in
addition to the tumor cells.

22. Bacterial Viral Tubercular Fungal
Increased WBC count Increased WBC count Increased WBC count Increased WBC count
Neutrophils Lymphs Lymps & Monos Lymphs & Monos
Marked ↑ protein Mod. ↑ protein Mod-Marked ↑
protein
Mod-Marked ↑
protein
Marked ↓ glucose ↔ normal glucose ↓ glucose Normal to ↓
glucose
Lactate > 35
mg/dL
Lactate normal Lactate > 25 mg/dL Lactate > 25
mg/dL
+ gram stains Pellicle formation + India ink with
Cryptococcus
neoformans
+ bacterial
antigen tests
+ immunological
test for C. neo.

23.  A lumbar puncture also called a spinal tap is a
procedure where a sample of cerebrospinal fluid is
taken for examination.
 CSF is mainly used to diagnose meningitis [an
infection of the meninges].
 It is also used to diagnose some other conditions of
the brain and spinal cord.

24.  Patient usually lie on a bed on side with knees
pulled up against the chest.
 Push a needle through the skin and tissues between
L3 & L4 vertebra into the space around the spinal
cord which is filled with CSF.
 CSF leaks back through the needle and is collected in
a sterile container.
 As soon as the required amount of fluid is collected
the needle is taken out and a plaster is put over the
site of needle entry.