Cerebrospinal Fluid (CSF) and Meninges

Supplies nutrients to the nervous system; removes metabolic waste; provides a mechanical barrier that cushions the brain and spinal cord against trauma.

Dura mater; Arachnoid mater; Pia mater.

Dura mater – outer layer lining the skull and vertebral canal; Arachnoid mater – spiderweb-like filamentous inner membrane; Pia mater – innermost layer lining the surface of the brain and spinal cord.

The space below the arachnoid mater where CSF flows.

Choroid plexus; through selective filtration; 20 mL/hour.

Arachnoid villi or arachnoid granulations.

Protects the brain from chemicals and other substances circulating in the blood that may harm brain tissue.

WBCs, proteins, and other chemicals enter the CSF; examples include meningitis and multiple sclerosis.

Lumbar puncture; between L3–L4 in adults and L4–L5 in infants.

Up to 20 mL if CSF pressure is normal; normal pressure is 50–180 mmHg.

Only 1–2 mL.

Adults: 90–150 mL; Neonates: 10–60 mL.

Tube 1 – Chemistry/Serology; Tube 2 – Microbiology; Tube 3 – Hematology.

Tube 1 – Freezing temperature; Tube 2 – Room temperature for 30 minutes or 35–37°C; Tube 3 – Refrigeration temperature.

Tube 1.

Tube 2.

Tube 3.

Microbiology or serology; provides better exclusion of skin contamination or allows additional tests.

Tubes 1 and 4.

Microbiology first; Hematology second; Chemistry/Serology last.

Supernatant may be used for additional chemical or serologic tests; excess fluid should not be discarded and should be frozen until no further use is needed.

Crystal clear.

Increased WBCs (>200/µL), RBCs (>400/µL), lipids, proteins, or microorganisms.

Pink, yellow, or orange discoloration of CSF due to hemoglobin degradation products; it is most commonly caused by hemoglobin breakdown.

Pink – slight amount of oxyhemoglobin; Yellow – oxyhemoglobin converted to bilirubin; Orange – heavy hemolysis.

Increased carotene; increased melanin; increased protein (>150 mg/dL); rifampin.

Greater than 6,000 RBCs/µL.

Traumatic tap and intracranial hemorrhage.

Traumatic tap – uneven distribution (Tube 1 > Tube 2 > Tube 3); Intracranial hemorrhage – even distribution (Tube 1 = Tube 2 = Tube 3).

Traumatic tap – positive due to plasma fibrinogen; Intracranial hemorrhage – negative because CSF normally has no fibrinogen.

Traumatic tap – clear; Intracranial hemorrhage – xanthochromic due to RBC lysis after approximately 2 hours.

Macrophages containing ingested RBCs; present in intracranial hemorrhage.

Hematoidin and hemosiderin.

Traumatic tap – negative; Intracranial hemorrhage – positive.

Radiographic contrast media.

Presence of protein and clotting factors; associated with meningitis, Froin syndrome, and blockage of CSF circulation.

A film-like formation associated with tubercular meningitis.

WBCs and RBCs begin to lyse within 1 hour; approximately 40% of WBCs disintegrate within 2 hours.

Adults: 0–5 WBCs/µL; Neonates: 0–30 WBCs/µL.

Clear – undiluted; Slightly hazy – 1:10; Hazy – 1:20; Slightly cloudy – 1:100; Cloudy/slightly bloody – 1:200; Bloody/turbid – 1:10,000.

Only in cases of traumatic tap.

Subtract 1 WBC for every 700 RBCs observed.

Subtract 8 mg/dL total protein for every 10,000 RBCs/µL.

Subtract 1 mg/dL total protein for every 1,200 RBCs/µL.

Using a stained smear after concentrating the specimen.

Cytocentrifugation; centrifugation; sedimentation; filtration.

A device that forces cells from fluid in a conical chamber into a monolayer within a 6-mm diameter circle on a slide.

Increases cell yield or recovery; decreases cellular distortion.

Predominant – lymphocytes and monocytes; Occasional – neutrophils.

70:30 (70% lymphocytes and 30% monocytes).

Up to 80% lymphocytes.

An abnormal increase in the number of normal cells in CSF.

Lymphocytes – viral, tubercular, and fungal meningitis; multiple sclerosis. Monocytes – may accompany lymphocytic reactions and inflammatory conditions.

Bacterial meningitis; early viral, tubercular, and fungal meningitis; cerebral hemorrhage.

Their granules may be less prominent than those in blood; cells disintegrate rapidly.

Cells associated with RBCs in spinal fluid or contrast media; may contain phagocytized RBCs appearing as empty vacuoles or ghost cells, hemosiderin granules, and hematoidin crystals.

Acute leukemia; lymphoblasts, myeloblasts, or monoblasts.

Disseminated lymphoma; resemble lymphocytes with cleft nuclei.

Associated with multiple sclerosis and lymphocyte reactions; traditional and classic forms may be observed.

Diagnostic procedures; they appear in clusters with distinct nuclei and cell walls.

Metastatic carcinomas or primary CNS carcinoma; cells appear in clusters with fused cell borders and nuclei.

Adults: 15–45 mg/dL; Infants: 150 mg/dL; Immature individuals: 500 mg/dL.

CSF protein is less than 1% or approximately 1/200 of serum protein.

Damage to the blood-brain barrier (BBB).

Meningitis; hemorrhage; intrathecal immunoglobulin production (multiple sclerosis); decreased normal protein clearance; neural tissue degeneration.

CSF leakage or trauma; recent puncture; rapid CSF production; water intoxication.

Albumin.

Prealbumin.

Haptoglobin and ceruloplasmin.

Carbohydrate-deficient transferrin found in CSF but not in serum.

IgG and some IgA.

IgM; fibrinogen; lipids.

Multiple sclerosis.

It is a CSF-associated protein that is not found in serum.

BBB damage; increased immunoglobulin production within the CNS; decreased normal protein clearance.

Lymphocytes and monocytes.

Neutrophils.

Lymphocytes and plasma cells.

Blast forms, including lymphoblasts, myeloblasts, and monoblasts.

Macrophages.

Pleocytosis refers to an abnormal increase in normal CSF cells, whereas normal CSF contains predominantly lymphocytes and monocytes.

To improve cell recovery and allow adequate identification of cells.

Tube 3; refrigeration temperature.

Tube 1; freezing temperature.

Tube 2; room temperature for 30 minutes or 35–37°C.

RBCs lyse after approximately 2 hours, releasing hemoglobin that produces xanthochromic discoloration.

Traumatic tap – absent; Intracranial hemorrhage – present.

Hazy/turbid/cloudy – increased cells, protein, lipids, or microorganisms; Xanthochromic – hemoglobin degradation products; Bloody – increased RBCs.

Hemoglobin degradation products.

It favors traumatic tap.

It favors intracranial hemorrhage.

70% lymphocytes and 30% monocytes.

Neutrophils may also be present during the early stages of these infections, not only in bacterial meningitis.

Damage to the BBB; production of immunoglobulins within the CNS.

Beta-2 transferrin (tau).

15–45 mg/dL; less than 1% or approximately 1/200 of serum protein.

Both may cause increased CSF protein due to damage to the BBB.

Increased intrathecal immunoglobulin production; lymphocytes and plasma cells may be observed.

Normal – predominantly lymphocytes and monocytes, with occasional neutrophils; Abnormal – increased cells or the presence of neutrophils, macrophages, blast forms, lymphoma cells, plasma cells, or malignant cells depending on the condition.

Appearance; cell count and differential; protein concentration; specimen collection and handling; traumatic tap versus intracranial hemorrhage findings.