Evaluation of CSF

• Cerebrospinal fluid (CSF) is a clear fluid present in the ventricles of the brain, the central canal of the spinal cord, and the subarachnoid space.

• CSF is produced in the brain by modified ependymal cells in the choroid plexus (approx. 50-70%), and the remainder is formed around blood vessels and along ventricular walls.

Functions of CSF

• Protects, lubricates the brain• Provides nutrients, removes waste 90-150 ml adult 10-60 ml in newborn• Modulates pressure changes (Buoyancy) • Serves as a chemical buffer to maintain

constant ionic environment• Serves as a transport medium for nutrients

and metabolites, endocrine substances and even neurotransmitters

Circulation of CSFLateral ventricles

interventricular foramen of Monroe

third ventricle

mesencephalic aqueduct (aqueduct of Sylvius)

fourth ventricle

spinal cord central canal; also, out the lateral apertures to the subarachnoid

space to the venous system

Circulation of CSF

Normal CSF

• Thin, colourless, clear fluid• Pressure 90-180mm WATER (10-100 neonates)• 0-5 WBC’s /mm3 (neonates 0-30/ mm3 ) (Lymphocytes & monocytes)• Occasional ependymal or choroid plexus cells• Protein 15-45mg/dl• Glucose 50-80mg/dl• Chloride 113-130 mEq/L• Sterile

• Appearance• Normal - Crystal clear, colorless• Descriptive Terms – hazy, cloudy, turbid, milky, bloody, xanthrochromic • Often are quantitated – slight, moderate, marked, or grossly. • Clots indicate traumat tap• pellicle formation –cobweb • Milky – increased lipids• Oily – contaminated with x-ray – media

• Xanthrochromic – Yellowing discoloration of supernatent (may be pinkish, or orange).• Most commonly due to presence of ‘old’

blood.• Other causes include increased bilirubin,

carotene, proteins, melanoma

• Cerebral hemorrhage• Even distribution of blood in the numbered tubes• Clot formation possible• Xanthrochromic supernatent

• – RBCs must have been in CSF @ 2+ hours• - D-dimer, fibrin degradation product from hemorrhage site• Microscopic presence of erythrophages, or siderophages,

Hemosiderin granules

Traumatic collection vs cerebral hemorrhage

Lumbar puncture

• a lumbar puncture (or LP, and colloquially known as a spinal tap)

• is a diagnostic procedure that is performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis

indications

1. To obtain CSF sample for cytological,chemical,cellular and bacteriological examination

2. To aid in therapy by the administration of soinal anesthetics and occasionally antibiotics or antitumor agents or by reduction of CSF pressure

3. To inject radiopaque substance as in myelography, or a radioactive agent , as in radionuclide cisternography.

complications

1. Headache2. Brain herniation3. Diplopia4. Subarachnoid haemorrhage5. Spinal epidural hematoma

contraindications

1. Infection2. Pailloedema3. Bleeding diathesis4. Severe pulmonary disease

COMMON FORMS OF MENINGITISCONDITION PRESSURE LEUKOCYTE PROTIEN GLUCOSE COMMENTS

Aute bacterial

Elevated(100-300)

100-10,000Usually PMN’s

100-500 Reduced <40< 50% of s.glucose

Gram stain or culture

Partially treated

Normal/elevated

5-10,000Usually PMN’s/mononuclear cells

100-500 Normal/reduced

Gram stain or anitgen detectionby agglitination test

Viral meningitis

Normal or slightly elevated

Rarely >1000 cells.intiallly PMN then lymph

50-200 Normal or reduced <40

Viral cultures/PCR, CT/MRI

Uncommon formsCONDITION PRESSURE LEUKOCYTE PROTEIN GLUCOSE COMMENTS

TBM Usually elevated

10-500, all lymphocytes

100-300, higher due to block

<50 % CSF is turbid with cobweb coagulum/PCR

syphilis Usually elevated

5-500 , all lymphocytes

50-200 Usually normal

CSF serology

Amoebic elevated 1,000 – 10,000,PMN’s

50-500 normal Mobile amoeba in hanging drop CSF exam.

Fungal meningitisORGANISM WBC’s PROTIEN GLUCOSE SMEARS SEROLOGY CULTURES

blastomyces

15,000(PMN’s/lymph)

300 normal rare No good rare

candida 600-1900 (mixed)

elevated low 40% positive

No good useful

coccidioides

100-750(lymphocytes)

150-2000 21 – 62% rare Antibody positive in 95% cases

Positive in 60 %

cryptococcus

40 – 400(lymphocytes)

high low India ink positive (25-50%)

Antigen positive(90%)

Positive in 75%

histoplasma

0 – 300(mixed)

normal Low(<40) rare Antigen positive (61%)

Positive (27-65%)

Brain abscess and parameningeal focus

condition pressure leukocyte protein glucose comments

Brain abscess Elevated(100-300)

5-200(lymphocytes)

75-500 normal Sterile,unless ruptures

Subdural empyema

Elevated(100-300)

100-5000(PMN)

100-500 normal sterile

Cerebral epidural abscess

normal 100-500(lymphocytes)

100-500 normal sterile

Spinal epidural abscess

low with spinal block

10-100(lymphocytes)

50-400 normal sterile

Chemical(drugs,dye,dermoid cyst)

elevated 100-1000(PMN)

50-100 Normal or decreased

Epithelial cells with dermoid

noninfectiouscondition pressure leukocyte protein glucose others

sarcoidosis normal 0-100(mononuclear)

40-100 normal none

SLE elevated 0-500(PMN) 100 Normal or decreased

Culture sterile

Tumors/leukemia

Elevatedto very high

0-100 50-1000 Normal to decreased

Cytology positive

SAH Opening pressure high

Normal increased normal xanthochromia

Demyelinating disorder condition pressure leukocyte protein glucose others

Multiple sclerosis

normal < 50 (lymphocytes)

normal normal MRI

ADEM normal > 50 (lymphocytes)

normal normal