To examine the spinal fluid for diagnosis of four major disease categories:
Central nervous system (CNS) malignancy (meningeal carcinoma, tumor metastasis)
Autoimmune disease and multiple sclerosis (MS)
To determine level of CSF pressure, to document impaired CSF flow, or to lower pressure by removing volume of fluid
To identify disease-related immunoglobulin patterns (IgG, IgA, and IgM referenced to albumin) in neurotuberculosis, neuroborreliosis, or opportunistic infections
TABLE 5.1 Normal CSF Values
Adult: 90-150 mL; child: 60-100 mL
Adult: 90-180 mm H2O; child: 10-100 mm H2O
Total cell count
Essentially free cells
Microscopic Examination of Cells
Newborn (0-14 d)
RBCs (has limited diagnostic value)
Newborn (0-14 d)
40-70 mg/dL (2.2-3.9 mmol/L)
60-80 mg/dL (3.3-4.4 mmol/L)
Adults: 15-45 mg/dL (150-450 mg/L)
Elderly (>60 yr): 15-60 mg/dL (150-600 mg/L)
Neonates: 15-100 mg/dL (150-1000 mg/L)
15-25 mg/dL (150-250 mg/L)
5-15 mg/dL (50-150 mg/L)
Lactic acid (lactate)
10-24 mg/dL (1.11-2.66 mmol/L)
5-20 mg/dL (0.34-1.37 mmol/L)
10-35 mg/dL (1.52-5.32 mmol/L)
6-16 mg/dL (2.14-5.71 mmol/L)
0.5-1.2 mg/dL (44-106 mmol/L)
0.5-4.5 mg/dL (29.7-268 mmol/L)
1.2-2.0 mg/dL (387-646 mmol/L)
10-35 mg/dL (5.87-20.5 mmol/L)
Lactate dehydrogenase (LDH) (10% of serum level)
Adult: 0-40 U/L (0-0.67 mkat/L)
Electrolytes and pH
Newborn (0-14 d)
115-130 mEq/L (mmol/L)
135-160 mEq/L (mmol/L)
2.6-3.0 mEq/L (mmol/L)
20-25 mEq/L (mmol/L)
44-50 mm Hg (5.8-6.6 kPa)
40-44 mm Hg (5.3-5.8 kPa)
2.0-2.8 mEq/L (mmol/L)
1.0-1.4 mEq/L (mmol/L)
2.4-3.0 mEq/L (mmol/L)
1.2-1.5 mEq/L (mmol/L)
280-300 mOsm/kg (280-300 mmol/kg)
Serology and Microbiology
>1.5 indicates chronic inflammatory process
<0.4 probably not acute inflammatory process
CSF, cerebrospinal fluid; RBCs, red blood cells; VDRL, Venereal Disease Research Laboratory; WBCs, white blood cells.
Be sure to include patient’s age because it is needed to evaluate borderline values.
To introduce anesthetics, drugs, or contrast media used for radiographic studies and nuclear scans into the spinal cord
To confirm the identity of pathogens involved in acute inflammatory or chronic inflammatory disorders (e.g., MS and blood-brain barrier dysfunction)
To identify extent of brain infarction or stroke
To formulate antibody index (AI) of the IgG class for polyspecific immune response in the CNS. Examples: measles, rubella, and zoster (MRZ) antibodies to viruses in MS; herpes simplex virus (HSV) antibodies in MS; toxoplasma antibodies in MS; and autoantibodies to double-stranded DNA (ds-DNA)
To identify brain-derived proteins, such as neuron-specific enolase present after brain trauma
CSF pressure is measured.
General appearance, consistency, and tendency of the CSF to clot are noted.
CSF cell count is performed to distinguish types of cells present; this must be done within 2 hours of obtaining the CSF sample.
CSF protein and glucose concentrations are determined.
Other clinical serologic and bacteriologic tests are done when the patient’s condition warrants (e.g., culture for aerobes and anaerobes or tuberculosis).
Tumor markers may be present in CSF; these tests are useful as supplements to CSF cytology analysis (Table 5.2).
TABLE 5.2 Tumor Markers in CSF
Blood levels for specific substances should always be measured simultaneously with CSF determinations for meaningful interpretation of results.
Before lumbar puncture, check eyegrounds (fundus of the eye as visualized with an ophthalmoscope) for evidence of papilledema (swelling of the optic disc generally due to an increase in ICP) because its presence may signal potential problems or complications of lumbar puncture.
A mass lesion should be ruled out by computed tomography (CT) scan before lumbar puncture because a mass lesion can lead to brainstem herniation.
If increased pressure is found while performing the lumbar puncture, it should not be necessary to stop the procedure unless neurologic signs are present.
Place the patient in a side-lying position with the head flexed onto the chest and knees drawn up to, but not compressing, the abdomen to “bow” the back. This position helps to increase the space between the lower lumbar vertebrae so that the spinal needle can be inserted more easily between
the spinal processes. However, a sitting position with the head flexed to the chest can be used. The patient is helped to relax and instructed to breathe slowly and deeply with his or her mouth open.
Select the puncture site, usually between L4 and L5 or lower. There is a small bony landmark at the L5-S1 interspace that helps to locate the puncture site. The site is thoroughly cleansed with an antiseptic solution, and the surrounding area is draped with sterile towels in such a way that the drapes do not obscure important landmarks (Fig. 5.2).
Inject a local anesthetic slowly into the dermis around the intended puncture site.
Insert a spinal needle with stylet into the midline between the spines of the lumbar space and slowly advance until it enters the subarachnoid space. The patient may feel the entry as a “pop” of the needle through the dura mater. Once this happens, the patient can be helped to straighten his or her legs slowly to relieve abdominal compression.
Remove the stylet with the needle remaining in the subarachnoid space and attach a pressure manometer to the needle to record the opening CSF pressure.
Remove a specimen consisting of up to 20 mL of CSF. Take up to four samples of 2 to 3 mL each, place in separate sterile screw-top tubes, and label with the patient’s name, date and time of collection, and test(s) ordered. Label the tubes sequentially: Tube 1 is used for chemistry and serology; tube 2 is used for microbiology studies; tube 3 is used for hematology cell counts; and tube 4 is used for special studies such as cryptococcal antigens, syphilis testing (Venereal Disease Research Laboratory [VDRL]), protein electrophoresis, and other immunologic studies. A closing pressure reading may be taken before the needle is withdrawn. In cases of increased ICP, no more than 2 mL is withdrawn because of the risk that the brainstem may shift.
Apply a small sterile dressing to the puncture site.
The correctly labeled specimens of CSF must be immediately delivered to the laboratory, where they should be given to laboratory personnel with specific instructions regarding the testing. CSF samples should never be placed in the refrigerator because refrigeration alters the results of bacteriologic and fungal studies. Analysis should be started immediately. If viral studies are to be performed, a portion of the specimen should be frozen.
Record procedure start and completion times, patient’s status, CSF appearance, and CSF pressure readings.
If the opening pressure is >200 mm H2O in a relaxed patient, no more than 2 mL of CSF should be withdrawn.
If the initial pressure is normal, Queckenstedt’s test may be done. (This test is not done if a CNS tumor is suspected.) In this test, pressure is placed on both jugular veins to occlude them temporarily and to produce an acute rise in CSF pressure. Normally, pressure rapidly returns to average levels after jugular vein occlusion is removed. Total or partial spinal fluid blockage is diagnosed if the lumbar pressure fails to rise when both jugular veins are compressed or if the pressure requires >20 seconds to fall after compression is released.
Explain the purpose, benefits, and risks of lumbar puncture and explain tests to be performed on the CSF specimen; present a step-by-step description of the actual procedure. Emphasize the need for patient cooperation. Assess for contraindications or impediments such as arthritis. Sedation or analgesia may be used.
Help the patient to relax by having him or her breathe slowly and deeply. The patient must refrain from breath holding, straining, moving, and talking during the procedure.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Have the patient lie prone for approximately 4 to 8 hours. Turning from side to side is permitted as long as the body is kept in a horizontal position.
Women may have difficulty voiding in this position. The use of a fracture bedpan may help.
Fluids are encouraged to help prevent or relieve headache, which is a possible result of lumbar puncture.
Review test results; report and record findings. Modify the nursing care plan as needed for abnormal outcomes and complications such as paralysis (or progression of paralysis, as with spinal tumor), hematoma, meningitis, asphyxiation of infants due to tracheal obstruction from pushing the head forward, and infection.
Observe for neurologic changes such as altered level of consciousness, change of pupils, change in temperature, increased blood pressure, irritability, and numbness and tingling sensations, especially in the lower extremities.
If headache occurs, administer analgesics as ordered and encourage a longer period of prone bed rest. If severe headache persists, an epidural blood patch may need to be done, in which a small amount of the patient’s own blood is introduced into the epidural space at the same level that the canal was previously entered.
Check the puncture site for leakage.
Document the procedure completion and any problems encountered or complaints voiced by the patient.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.
Extreme caution should be used when performing lumbar puncture in the following cases:
If ICP is elevated, especially in the presence of papilledema or split cranial sutures. However, with some cases of increased ICP, such as with a coma, intracranial bleeding, or suspected meningitis, the need to establish a diagnosis is absolutely essential and outweighs the risks of the procedure.
If ICP is from a suspected mass lesion. To reduce the risk for brain herniation, a less invasive procedure such as a CT scan or magnetic resonance imaging (MRI) should be done.
Contraindications to lumbar puncture include the following conditions:
Suspected epidural infection
Infection or severe dermatologic disease in the lumbar area, which may be introduced into the spinal canal
Severe psychiatric or neurotic problems
Chronic back pain
Anatomic malformations, scarring in puncture site areas, or previous spinal surgery at the site
If there is CSF leakage at the puncture site, notify the healthcare provider immediately and document findings.
Follow standard precautions (see Appendix A) when handling CSF specimens.
A lumbar puncture is performed (see Lumbar Puncture [Spinal Tap]).
Measure the CSF pressure before any fluid is withdrawn.
Take up to four samples of 2 to 3 mL each, place in separate sterile screw-top tubes, and label with the patient’s name, date and time of collection, and test(s) ordered. Label the tubes sequentially: Tube 1 is used for chemistry and serology, tube 2 is used for microbiology studies, tube 3 is used for hematology cell counts, and tube 4 is used for special studies.
Increases in CSF pressure can be a significant finding in the following conditions:
Intracranial tumors; abscess; lesions
Meningitis (bacterial, fungal, viral, or syphilitic)
Hypo-osmolality as a result of hemodialysis
Congestive heart failure
Superior vena cava syndrome
Thrombosis of venous sinuses
Conditions inhibiting CSF absorption
Decreases in pressure can be a significant finding in the following conditions:
Leakage of spinal fluid
Significant variations between opening and closing CSF pressure can be found in the following conditions:
Tumors or spinal blockage above the puncture site when there is a large pressure drop (no further fluid should be withdrawn)
Hydrocephalus when there is a small pressure drop that is indicative of a large CSF pool
Slight elevations of CSF pressure may occur in an anxious patient who holds his or her breath or tenses his or her muscles.
If the patient’s knees are flexed too firmly against the abdomen, venous compression will cause an elevation in CSF pressure. This can occur in patients of normal weight and in those who are obese.
A lumbar puncture is performed (see Lumbar Puncture [Spinal Tap]).
Compare the CSF with a test tube of distilled water held against a white background. If there is no turbidity, newsprint can be read through normal CSF in the tube.
Abnormal appearance (Table 5.3)—causes and indications:
Blood in CSF can be due to hemorrhage or result from trauma from the lumbar puncture. If blood in CSF is caused by subarachnoid or cerebral hemorrhage, the blood is evenly mixed in all three tubes. Table 5.4 describes differentiation of bloody spinal tap from cerebral hemorrhage. Clear CSF fluid does not rule out intracranial hemorrhage.
Turbidity is graded from 1+ (slightly cloudy) to 4+ (very cloudy) and may be caused by the following conditions:
Leukocytes (pleocytosis [i.e., an increase in the number of cells—in this case, white blood cells (WBCs)—which is referred to as leukocytosis ])
Microorganisms such as fungi and amebae
Aspirated epidural fat (pale pink to dark yellow)