Medical Analysis

CSF Examination Part 1: Comprehensive Diagnostic Overview, Procedures, Indications, and Contraindications

Introduction and Clinical Significance of Cerebrospinal Fluid Analysis

Cerebrospinal Fluid (CSF) Examination is an extensive and clinically significant topic [13, 14]. Its proper understanding is crucial, as the findings profoundly influence both diagnosis and prognosis, directly impacting patient care and clinical decision-making [13, 14]. Due to the vastness of this subject, it is not feasible to cover every aspect within a single presentation [13, 14]. This presentation is one of a series of six presentations on CSF Examination [13, 14]. Viewers are encouraged to go through the remaining five presentations for a complete and comprehensive understanding of this topic [13, 14]. Thank you for your attention and commitment to learning [13, 14].

Fundamental Anatomy, Formation, and Physiological Functions of CSF

Cerebrospinal fluid is a clear, colorless fluid formed in the ventricles of the brain mainly by the choroid plexus, which is a meshwork of tiny small blood vessels located in the lateral, third, and fourth ventricles [13, 14]. It is mainly an ultrafiltrate of plasma [13, 14]. CSF is contained within the cerebral ventricles, the spinal canal, and the subarachnoid space, defined as the space between the arachnoid externally and the pia mater internally, surrounding the brain and spinal cord [13, 14]. Furthermore, CSF is reabsorbed into the blood through the arachnoid villi of dural venous sinuses [13, 14].

The primary functions of CSF include the protection of the brain and spinal cord from injury by acting as a shock absorber, and serving as a medium between the blood and the brain for the supply of nutrients to and the removal of waste products from the brain [13, 14].

Diagnostic Indications for Cerebrospinal Fluid Examination

Examination of CSF is indicated for diagnosis in suspected cases of central nervous system infections such as meningitis and encephalitis, meningeal involvement by leukemia or malignancy, subarachnoid hemorrhage if a CT scan is not available, inflammatory diseases such as multiple sclerosis and Guillain-Barre syndrome, and neoplasms of the central nervous system [13, 14, 15]. Additional diagnostic goals include reducing CSF pressure in benign intracranial hypertension or pseudotumor cerebri, the introduction of radiographic contrast media for myelography, and performing Queckenstedt test [13, 14].

Further indications involve the administration of medications such as anesthetic agents, antibiotics including amphotericin B in fungal meningitis, and anticancer drugs like methotrexate [13, 14]. It is also utilized for evaluating infections of the brain and spinal cord, neurosyphilis, meningeal carcinomatosis or lymphomatosis, dementia and other neurodegenerative diseases, unexplained seizures or fever, and the clinical follow-up in meningitis [13, 14, 15].

Contraindications and Safety Risks of Lumbar Puncture

Several critical contraindications restrict the performance of a lumbar puncture, notably raised intracranial pressure due to a space-occupying lesion such as a brain abscess, posterior fossa tumor, subdural hematoma, or epidural abscess [13, 14]. Other contraindications include cardiorespiratory compromise, a bleeding diathesis that has not been corrected, and local infection at the site of the lumbar puncture [13, 14].

Sample Collection Criteria and Procedural Protocols

The procedure involves selecting the subarachnoid space of the L3-L4 or L4-L5 vertebrae as the puncture site, utilizing a 22G lumbar puncture needle, and allowing up to 20 ml of fluid to be removed [13, 14]. The collected fluid is divided into four serially collected sterile tubes [13, 14]. Glass tubes must be avoided because cell adhesion affects counts [13, 14, 15]. The samples must be examined quickly, and refrigeration is strictly contraindicated for culture [13, 14, 15].

Distribution of Serially Collected CSF Sample Tubes

Complications Associated with Lumbar Puncture

Potential complications resulting from a lumbar puncture procedure include post-puncture headache, introduction of infection into the spinal canal, subdural hematoma, failure to obtain CSF known as a dry tap, herniation of the brain, and the development of a subarachnoid epidermal cyst [13, 14].

Normal Biochemical and Cellular Composition of Cerebrospinal Fluid

• Total volume: 100-150 ml, and 10-60 ml in the newborn [13, 14].

• Opening pressure: 60-180 mm of water in adults, and 10-100 mm in infants and young children [1, 2, 3, 4, 5].

• Appearance: Clear and colorless with no clots, possessing a viscosity similar to water [13, 14].

• Cells: Adults show 0-5 cells per cmm, infants show 0-30 cells per cmm, children aged 1-4 years show 0-20 cells per cmm, and children aged 5-18 years show 0-10 cells per cmm [13, 15].

• Glucose: 45-80 mg per dl, where normally CSF glucose is 60% or two-thirds of blood glucose [13, 14].

• Proteins: 15-45 mg per dl, where normally CSF proteins are 1% of plasma proteins [13, 14].

• Oligoclonal bands: Negative [6].

• Chloride: 120-130 mEq per L, which is 20 mEq per L more than the serum level [13, 14].

• Bilirubin: Absent [13, 14].

Overview of Tests Included in CSF Examination

Comprehensive evaluation parameters within a CSF examination protocol encompass opening pressure measurement, gross examination, microscopic examination, microbiological examination, chemical examination, and specialized investigations [13, 14, 15].

Summary and Acknowledgments

Trusted Insights. Curated by Dr. Dipak Ladda [13, 14].

For Non-Medicos

Essential Patient Guide to Cerebrospinal Fluid Testing

What is Cerebrospinal Fluid and Why Test It?

Cerebrospinal fluid is a protective, clear liquid surrounding your brain and spinal cord [13, 14]. Doctors analyze this fluid via a procedure called a lumbar puncture to diagnose serious conditions like brain infections, bleeding, or inflammation [13, 14].

Procedure Safety, Risks, and Normal Values

During the test, a fine needle safely extracts a small sample from the lower back [13, 14]. While crucial for diagnosis, the test is avoided if there is severe brain swelling or bleeding disorders [13, 14]. Normal fluid looks like pure water with strict baseline ranges for cell counts, protein, and glucose [13, 14, 15].

References:

1. Gilland, O., Tourtellotte, W. W., O’Tauma, L., & Henderson, W. G. (1974). Normal cerebrospinal fluid pressure. J Neurosurg, 40, 587–593.

2. Albeck, M. J., Skak, C., Borgesen, S. E., & Gjerris, F. (1990). A simple manometric method for clinical measurement of cerebrospinal fluid pressure. Br J Neurosurg, 4, 195–200.

3. Avery, R. A., Shah, S. S., Chun, T. T., & Liu, G. T. (2010). Normal cerebrospinal fluid opening pressure in children. J Neurosurg Pediatr, 3, 201–205.

4. Ekstedt, J. (1978). CSF hydrodynamic studies in man. 2. Normal hydrodynamic variables related to CSF pressure and flow. J Neurol Neurosurg Psychiatry, 41, 345–353.

5. Minns, R. A., Engleman, H. M., & Stirling, H. (1989). Cerebrospinal fluid pressure in pyogenic meningitis. Arch Dis Child, 64, 811–819.

6. Link, H., & Tibbling, G. (1977). Principles of CSF analysis in patients with multiple sclerosis. Scand J Clin Lab Invest, 37, 397–401.

7. Froin, G. (1903). Lésions sous-arachnoïdiennes et liquidiennes. Variations de l’albumine et de la coagulation. Gaz Hop Paris, 76, 1005–1006.

8. Vermeulen, M., & van Gijn, J. (1982). The diagnostic value of lumbar puncture in subarachnoid hemorrhage. Neurology, 32, 381–384.

9. Edlow, J. A., & Caplan, L. R. (2000). Avoiding pitfalls in the diagnosis of subarachnoid hemorrhage. N Engl J Med, 342, 29–36.

10. Wall, M., & George, D. (1991). Idiopathic intracranial hypertension. A prospective study of 50 patients. Brain, 114, 155–180.

11. Gray, L. W., Currie, S., & Hutchinson, P. J. (2008). Spectrophotometric analysis of cerebrospinal fluid for xanthochromia in suspected subarachnoid hemorrhage. Ann Clin Biochem, 45, 285–288.

12. Bonnici, J., O’Connell, M., & O’Donovan, D. (2011). Diagnostic utility of D-dimer in cerebrospinal fluid for distinguishing traumatic lumbar puncture from subarachnoid hemorrhage. Clin Chim Acta, 412, 432–435.

13. Seehusen, D. A., Reeves, M. M., & Fomin, D. A. (2003). Cerebrospinal fluid analysis. Am Fam Physician, 68(6), 1103–1108.

14. Doherty, C. M., & Forbes, R. B. (2014). Diagnostic lumbar puncture. Ulster Med J, 83(2), 93–102.

15. Engelborghs, S., Sleegers, K., Cras, P., et al. (2006). Collaborative multicenter study of the variability of cerebrospinal fluid analysis. Clin Chem Lab Med, 44(8), 968–977.

FAQ’s:

1. What is part 1 about?
It covers CSF introduction, lumbar puncture procedures, indications, and contraindications.

2. Where is CSF formed?
CSF is formed in the brain ventricles mainly by the choroid plexus.

3. What are the main functions?
It acts as a shock absorber and supplies nutrients while removing waste.

4. When is CSF examination indicated?
For diagnosing CNS infections, malignancies, subarachnoid hemorrhage, and inflammatory diseases.

5. What are LP contraindications?
Raised intracranial pressure, cardiorespiratory compromise, uncorrected bleeding diathesis, and local infection.

6. What is the puncture site?
The subarachnoid space of the L3-L4 or L4-L5 vertebrae.

7. How many tubes are collected?
Collected into four serially numbered sterile tubes for specific laboratory tests.

8. What are lumbar puncture complications?
Post-puncture headaches, infection introduction, subdural hematoma, dry taps, and brain herniation.

9. What is normal CSF pressure?
Normal opening pressure ranges from 60 to 180 mm of water in adults.

10. What are normal CSF cells?
Adults normally have 0 to 5 cells per cmm in cerebrospinal fluid.

Related Tests

• CSF Culture and Sensitivity