CSF Analysis Flashcards
What is cerebrospinal fluid (CSF)?
A clear fluid that surrounds the brain and spinal cord, providing protection and support
CSF is produced by the choroid plexus and circulates through the ventricles.
What is the normal production rate of CSF per day?
400 – 600 mL/day
The typical volume of CSF in the human body is 150 – 250 mL.
What are the primary functions of CSF?
- Mechanical protection
- Biochemical homeostasis
- Metabolic support
- Waste removal
What are common indications for CSF analysis?
- CNS infections
- Hemorrhage in CNS
- Demyelinating diseases
- CNS malignancy
- CSF leakage from ear or nose
How is CSF obtained for analysis?
By lumbar puncture at L3-L4, L4-L5, or L5-S1
Aseptic technique is crucial during sampling.
What are the contraindications to performing a lumbar puncture?
- Bleeding diatheses
- Space occupying intracranial lesions
- Infection at the needle site
What is the normal range for CSF opening pressure in adults?
6 – 25 cmH20, median 20
A pressure above 28 cmH20 is considered pathological.
What does xanthochromia in CSF indicate?
The presence of bilirubin, often due to breakdown of red blood cells
It can also result from elevated protein levels or severe jaundice.
What is the normal range for leukocytes in CSF?
0 - 5 per mm3 (μL)
An increase may indicate infection or other pathological conditions.
What is the significance of elevated CSF protein levels?
Indicates possible traumatic tap, infection, or obstruction
Normal values are 0.15 – 0.45 g/L in adults.
What does an increased CSF lactate level indicate?
Increased anaerobic metabolism, often related to hypoxia or CNS infections
CSF lactate does not cross the blood-brain barrier.
What does the presence of oligoclonal bands in CSF suggest?
Intrathecal synthesis of immunoglobulins, often indicative of multiple sclerosis
Oligoclonal bands are not typically present in serum.
What is the CSF glucose level in relation to plasma glucose?
Typically 2/3 of plasma concentration
A decrease may indicate increased utilization by cells or microorganisms.
What does a positive CSF culture indicate?
The presence of causative organisms in infections
Staining can help identify specific pathogens.
What is the role of CSF adenosine deaminase in diagnostics?
Indicator of CNS infections, particularly tuberculosis
Non-specific increases can occur in cryptococcal meningitis.
What characterizes bacterial meningitis in CSF analysis?
- Appearance: Turbid
- Glucose CSF: serum ratio: <0.45
- Total protein: ↑↑
- Cell count: Predominantly PMNs
What is the significance of measuring CSF chloride levels?
Used in the diagnosis of tuberculous meningitis
Low levels of CSF chloride can indicate CNS infections.
What is the interpretation of CSF findings in subarachnoid hemorrhage (SAH)?
May show xanthochromia and increased RBC count
CT scans are most reliable within 12 hours of symptoms.
What are the potential complications of a lumbar puncture?
- Headaches
- Diplopia
- Spinal epidural hematoma
- Brain herniation
What does an increased IgG index in CSF suggest?
Increased intrathecal production of IgG
Normal range is 0.32–0.60.
What are common symptoms of CNS infections?
- Fever
- Neck stiffness
- Headaches
- Neurological deficits
What is the role of CSF in metabolic support?
Provides buoyancy, reducing the effective weight of the brain
It also helps in metabolic homeostasis.
What does a clear CSF sample indicate?
Normal or non-pathological findings
Changes in color or turbidity often indicate pathology.
What are the components typically analyzed in CSF testing?
- Glucose
- Protein
- Lactate
- Electrolytes
- Cell counts
- Cultures
