1. CSF analysis

2. Cerebrospinal Fluid

3. CSF Formation 140 ml spinal and cranial CSF 30 ml in the spinal cord
Production is approx ml/min

4. Location of CSF Two lateral ventricles Third ventricle
Fourth ventricle
Spinal cord central canal
Subarachnoid space

5. Formation of CSF
Choroid plexuses of lateral, third and fourth ventricles
Ependymal lining of ventricular system
Blood vessels

6. Circulation of CSF Due to pulsation of blood in choroid plexus
Due to pulsation of ependymal cells
Lateral ventricles Interventricular Foramen of Monro third ventricle
Mesencephalic Aqueduct (Aqueduct of Sylvius) fourth ventricle spinal cord central canal through the Median Foramen of Magendie; also, out the Lateral Apertures of Luschka to the subarachnoid space. 6

8. Absorption of CSF
Through the arachnoid villi, a protrusion of arachnoid membrane into the central venous sinus and other sinuses
A valve opens when CSF pressure exceeds venous pressure
Absorption by veins and capillaries of CNS

12. Specimen Collection

13. Lumbar Puncture

14. Indications for Lumbar Puncture
Primary indication for emergent spinal tap is possibility of CNS infection
The second indication for an emergent spinal puncture is a suspected spontaneous subarachnoid hemorrhage.

15. Infectious Indications
Fever of unknown origin
Children 1mo to 3yrs: fever, irritability, and vomiting. Cannot comfort child
Over age 3yrs: nuchal rigidity, Kernig’s sign, and Brudzinski’s sign
Petechial rash in a febrile child
Partially treated children are less likely to be febrile or exhibit an altered mental status

16. Contraindications for LP
Absolutely contraindicated in the presence of infection in the tissues near the puncture site.
Relatively contraindicated in presence of increased ICP.
Caution advised when lateralizing signs.

17. Indications
1. Suspected CNS infection
2. Suspected subarachnoid hemorrhage
3.Sampling of CSF for any other reason
Contraindications
1. Local skin infections over proposed puncture site (absolute contraindication)
2. Raised intracranial pressure (ICP)
3. Suspected spinal cord mass or intracranial mass lesion (based on lateralizing neurological findings or papilledema)
4. Uncontrolled bleeding diathesis
5. Spinal column deformities

18. Equipment Spinal needle Three-way stopcock Manometer 4 specimen tubes
Local anesthesia
Drapes
Betadine

20. Procedure
Performed with the patient in the lateral recumbent position.
A line connecting the posterior superior iliac crest will intersect the midline at approx. the L4 spinous process.
Spinal needles entering the subarachnoid space at this point are well below the termination of the spinal cord.

22. Procedure
Almost all patients are afraid of an LP. Explaining the procedure in advance and discussing each step aids in reducing anxiety.
Inquire about allergies to anesthetics.
Informed consent.

23. Procedure Sterile gloves MUST be used.
Wash back with antiseptic solution.
Sterile towel under hips.
The skin and deeper subcutaneous tissue are infiltrated with local anesthetic.

24. Procedure
The patient should be told to report any pain and should be informed that he or she will feel some pressure.
The needle is placed into the skin in the midline parallel to the bed.

25. Procedure
The ligaments offer resistance to the needle, and a “pop” is often felt as they are penetrated.
Clear fluid will flow from the needle when the subarachnoid space has been penetrated.

26. Procedure
If bone is encountered, withdrawal into subcutaneous tissue and redirect.
Attach a manometer and record opening pressure.
Turn stopcock and collect fluid.
Withdrawal needle and place a dressing.
Instruct patient to remain lying down for 1-2 hours before getting up

27. Procedure Tube 1 is used for determining protein and glucose
Tube 2 is used for microbiologic and cytologic studies
Tube 3 is for cell counts and differential
Tube 4 reserve tube for any special tests

28. Interpretations Opening pressure Cloudiness / Turbidity Cells Glucose
Protein

29. Interpretations Opening Pressure
Opening pressure is taken promptly, avoiding falsely low values due to leakage through and around the needle
Normal pressure is between 80 and 180 mm Hg

30. Normal = mmHg
If elevated, likely due to cerebral edema from intracranial pathology

31. Interpretation Appearance (Cloudiness / Turbidity)
If CSF is not crystal clear, a pathologic condition of the CNS should be suspected
Compare fluid to water
Fluid may be clear with as many as 200 WBCs/mm3

32. A simple test of CSF turbidity is to see if normal print can be read easily through the sample – CSF should be crystal clear.
Cloudiness usually appears at CSF WBC counts > 200 WBCs/mm3

33. Interpretation
Cells
WBC counts over 5 cells/mm3 should be taken to indicate the presence of pathologic condition
Polymorphonuclear leukocytes are never seen in normal adults

34. Infections:
PMN predominance: likely bacterial meningitis.
Lymphocytic predominance: likely viral meningitis.

35. Interpretation
Cells
Neutrophilic pleocytosis is commonly associated with bacterial infections or early stages of viral infections.
Eosinophils are always abnormal and most commonly represent a parasite infestation.

36. Interpretation Cells Normal CSF RBCs are less than 5/mm3.
Counts that are otherwise unexplained may be due to a traumatic tap.

37. The Traumatic Tap
It should not be difficult to distinguish between subarachnoid hemorrhage and a traumatic tap.
In traumatic taps, the fluid generally clears between 1st and 3rd tubes.

38. Interpretation Glucose
Low CSF glucose concentration indicates increased glucose use in the brain and the spinal cord.
The normal range of CSF glucose is between 50 and 80 mg/dl
50-70% of serum glucose concentration
Only low concentrations of glucose are significance

39. Hypoglycorrhachia:
Decreased sugar level in CSF
Decreased glucose transport by the inflamed meninges.
Due to increased glucose utilization by the cerebral tissue.

40. Interpretation Protein
Increase in CSF total protein levels are a nonspecific abnormality associated with many disease states.
Levels > 500mg/dl are uncommon and are seen mainly in meningitis, in subarachnoid bleeding, and with spinal tumors.

41. Raised CSF protein levels are due to increased vascular permeability of the blood-brain barrier and the loss of albumin-rich fluid from the capillaries.

42. CSF Analysis with Infections
Bacterial Infections
The Gram stain is of great importance, because this often dictates the initial choice of antibiotic.
Gram-negative intracellular or extracellular diplococci are indicative of Neisseria meningitidis
Small Gram-negative bacilli may include Haemophilus influenza, especially in children.
Gram-positive cocci indicates Streptococcus pneumoniae, other Streptococcus species, or Staphylococcus.
20% of Gram stains may be falsely negative.

43. CSF Analysis with Infections
Bacterial Infections
While the culture is pending, one may suspect a bacterial infection in the presence of an elevated opening pressure and a marked pleocytosis ranging between 500 and 20,000 WBCs/mm3.
The differential count is usually chiefly neutrophils.
A count above 1000 cells/mm3 seldom occurs in viral infections.

44. CSF Analysis with Infections
Bacterial Infections
CSF glucose levels less than 40 mg/dl or less than 50% of a simultaneous blood glucose level should raise the question of bacterial meningitis.
The CSF protein content in bacterial meningitis ranges from 500 to 1500 mg/dl.

45. CSF Analysis with Infections
Viral Studies
The organisms most commonly isolated in viral meningitis are enteroviruses and mumps.
Enteroviruses: summer and fall
Mumps: winter and spring

46. CSF Analysis with Infections
Viral Studies
WBC count in viral meningitis and encephalitis usually: 10 to 1000 cells/mm3.
The differential count is predominantly lymphocytic and mononuclear in type.
Protein levels are usually mildly elevated

47. CSF Findings >1000 >50 50-80 ½ - 2/3 serum <30 < ½ serum
Component
Normal Children
Bacterial Meningitis
Viral Meningitis
Leukocytes/ mm3
WBC
0-5
>1000
Neutrophils (%)
>50
< 40
Glucose (mg/dL)
50-80
½ - 2/3 serum
<30
< ½ serum
<
Protein (mg/dL)
20-30
>100
50-100
Erythrocytes/mcL
0-2
0-10

48. Complications Headache After Lumbar Puncture Most common complication
Occurs 5-30% of all spinal taps
Usually starts up to 48 hours after to procedure.
Usually lasts 1-2 days (occas 14 days)

49. Meningitis
Meningitis is an inflammatory process of the leptomeninges and CSF