Norm of Lumbar Puncture
See Cerebrospinal fluid, Glucose—Specimen ; Cerebrospinal fluid, Immunoglobulin G, Immunoglobulin G ratios and immunoglobulin G index, Immunoglobulin G synthesis rate—Specimen ; Cerebrospinal fluid, Lactic acid—Specimen ; Cerebrospinal fluid, Myelin basic protein, Oligoclonal bands, Protein, and Protein electrophoresis—Specimen ; Cerebrospinal fluid, Routine analysis—Specimen ; Cerebrospinal fluid, Routine—Culture and cytology.
Usage of Lumbar Puncture
To assist in the diagnosis of primary or metastatic brain or spinal cord neoplasm, cerebral hemorrhage, meningitis, encephalitis, degenerative brain disease, autoimmune diseases involving the central nervous system, neurosyphilis, and demyelinating disorders (such as multiple sclerosis, acute demyelinating polyneuropathy). Also, this procedure may be performed therapeutically to inject therapeutic or diagnostic agents, to administer spinal anesthetics, or to reduce/drain volume of CSF to a normal level in benign intracranial hypertension (pseudotumor cerebri, idiopathic intracranial hypertension). See individual test listings above for additional specific usage.
Description of Lumbar Puncture
An invasive sterile procedure that can be performed at the bedside. A needle is placed into the subarachnoid space of the spinal column. Cerebrospinal fluid (CSF) pressure is measured, and CSF is obtained for examination. The spinal fluid is analyzed to diagnose spinal cord and brain diseases. CSF protects the brain and spinal column from injury and transports products of neurosecretion and cellular metabolism. Under special circumstances, CSF may be obtained from a ventriculotomy or from cisternal or lateral cervical punctures.
Professional Considerations of Lumbar Puncture
Consent form IS required.
Bleeding causing epidural hematoma, cerebral and spinal herniation, brain shift, cranial neuropathy, headache, hematoma (spinal subdural or intracranial occipital), increased intracranial pressure, infection, low back pain, meningitis, nausea, nerve root irritation.
Degenerative joint disease affecting the spine; an agitated or uncooperative client; infection near the L2-S1 site, which could carry the infective process into the CSF and change cytologic results; coagulation defects, low back pain, or spinal deformities; brain shift (usually characterized by headache and vomiting; papilledema may or may not be present).
Note: Comatose clients with high intracranial pressure but without brain shift may be candidates for lumbar puncture without prior CT when the need for the lumbar puncture diagnostic information is mandatory and urgent, such as in cases of suspected acute meningitis (van Crevel et al, 2002).
- See Client and Family Teaching.
- If a prescheduled procedure, verify whether client has stopped taking anticoagulants for the length of time required per the physician.
- Obtain a lumbar puncture or a spinal tap sterile tray, sterile drapes, 1%–2% lidocaine (Xylocaine), and a dry, sterile dressing.
- If increased intracranial pressure is suspected, a computed tomographic scan of the brain should be performed to rule out this possibility before the lumbar puncture. Herniation of the brain may occur in such clients.
- Assess the client's vital signs. Perform a baseline neurologic assessment of the legs by assessing strength, sensation, and movement.
- Client should empty bowel and bladder before the procedure.
- Just before beginning the procedure, take a “time out” to verify the correct client, procedure, and site.
- EMLA topical anesthetic cream may be prescribed for application to puncture site 30 minutes before the start of the procedure for children, in nonemergent situations.
- Position the client in a lateral position with the knees drawn up to the abdomen, the chin placed on the chest, and hands clasped around the knees.
- Assist the client in relaxing during the procedure by using soothing words and by instructing the client to breathe slowly and deeply with the mouth open. Give reassurance by using touch or holding the client's hand, unless this is opposed by the client.
- The puncture site is selected, usually in the lumbar sac at L3-L4 or at the L4-L5 site. A little bone at the L5-S1 interspace, the “surgeon's delight,” facilitates selection of the puncture site.
- The site is thoroughly cleansed with an antiseptic solution.
- The surrounding area is draped carefully with sterile towels such that the towels do not obscure important landmarks.
- A local anesthetic (usually lidocaine) is injected into the L3-L4 or L4-L5 spinal column area, creating a burning sensation.
- A spinal needle, which contains an inner obturator (stylet), is placed through the skin and into the spinal canal. Postdural puncture headache may be decreased if the Sprotte atraumatic needle or a Quincke needle is used.
- The subarachnoid space is entered. The client may feel the entry (a “pop”) of the needle through the dura mater. Postdural puncture headache prevalence decreases when the smallest needle possible is used and when the bevel of the needle is inserted parallel (instead of perpendicular) to the dural fibers. Note: In children a rule of thumb to use for mean insertion depth is 0.03 × height of child (in centimeters).
- The obturator is removed, and CSF will be seen slowly dripping from the needle.
- The needle is attached to a sterile manometer.
- Ask the client to relax and straighten the legs. This will reduce the intra-abdominal pressure, which will cause an increase in CSF pressure.
- The opening CSF pressure is recorded.
- Three numbered sterile polypropylene CSF transfer tubes are filled sequentially, with a total of 6–12 mL of CSF.
- The Queckenstedt procedure is performed during a lumbar puncture if blockage in the CSF circulation in the spinal subarachnoid space is suspected. The jugular vein is temporarily occluded manually by digital pressure or by a medium-sized blood pressure cuff inflated to approximately 20 mm Hg. The CSF pressure should increase to 15–40 cm H2O within 10 seconds of jugular occlusion. No rise after 10 seconds is suggestive of a complete obstruction in the spinal canal. The pressure should return promptly to normal within 10 seconds of release of pressure. A sluggish rise or fall of CSF pressure is suggestive of partial blockage of CSF circulation.
- The closing pressure of CSF is measured.
- One may decrease a puncture headache by pointing the face of the bevel in the direction of the client's side, replacing the stylet, and rotating the needle 90 degrees before withdrawing the needle.
- The procedure takes 30 minutes.
- Discard the first specimen, which is likely to be contaminated with blood. Label all test tubes immediately with the proper number (1, 2, 3), the client's name, the date, and the room number. Colored or very cloudy spinal fluid requires additional mixing with 0.5 mL of sterile sodium citrate per 5 mL of CSF to prevent clotting.
- Transport the specimens to the laboratory immediately. Analysis must be performed promptly on freshly collected specimens. Refrigerate the CSF or store the specimens for culture in a bacteriologic incubator when prompt analysis is not possible.
- Apply a dry, sterile dressing to the lumbar puncture site.
- Monitor vital signs and assess for changes in level of consciousness, headache, and neurologic status every 15 minutes × 4, every 30 minutes × 4, and then hourly × 4.
- Assess the client for numbness, tingling, and movement of the lower extremities; irritability; change in level of consciousness; nonreactive eye pupils; and ability to void.
- Assess the puncture site for redness, swelling, drainage, and pain every 4 hours for 24 hours. Notify the physician of any unusual findings. Notify the physician immediately if there is a sign of leakage at the puncture site.
- Encourage the client to drink increased amounts of fluid with a straw to replace CSF removed during the lumbar puncture, unless this is contraindicated.
- Headache is common after lumbar puncture, usually beginning within 48 hours and may last up to 4 months, but it usually resolves within 1 week. The cause is thought to be related to CSF hypotension caused by spinal fluid leak. However, this is not proven. There is no correlation between amount of postprocedure bed rest and the duration of the headache; however, lying still typically reduces the severity of the symptoms. Treatment sometimes involves injection of a blood patch into the epidural space, as well as medication for pain. The incidence of post-puncture headache progressively decreases as needle gauge decreases (Evans et al, 2000).
Client and Family Teaching
- Explain the procedure, potential risks and benefits, and postprocedural care. Allay the client's fears, and allow him or her time to verbalize concerns.
- There will be a burning sensation with the injection of local anesthetic, and transient pain or pressure may occur during the lumbar puncture.
- No fasting or sedation is required. Blood thinners may have to be stopped for preplanned procedures, depending on physician prescription.
- Empty the bladder and bowels before the procedure.
- You will have to lie on your side with your chin bent down onto your chest and clasp your hands around your knees. The knees should be drawn up to but not compress the abdomen so that the back bows. (A sitting position, with the client straddling a straight-backed chair and flexing the head to the chest, can also be used.)
- It is important to lie very still throughout this procedure because movement may cause accidental injury. Do not hold your breath, strain, or talk during procedure.
- Notify the physician or nurse if you are having severe back pain, numbness or tingling in the lower extremities, more than minor bleeding, headache that lasts more than 1 day, or a temperature higher than 101 degrees F (38.3 degrees C).
- Headaches are common after this procedure. They usually resolve on their own within a week.
- Avoid heavy lifting for 2 days after the procedure.
Factors That Affect Results
- Contamination of the specimen will cause inaccurate results. The first tube could be contaminated with blood from the spinal tap and should not be used for protein determination, cell count, or culture.
- A traumatic spinal tap could cause blood to be present in the specimen, and this may be mistaken for a clinical problem.
- Cloudy specimens may be caused by elevated white blood cells. Yellow specimens may be caused by elevated protein >100 mg/dL. Pink or red specimens may be caused by red blood cells. Turbid specimens may be caused by the presence of fungi.
- Refrigeration will alter the test results if bacteriologic and fungal studies are done.
- Certain drugs could cause a falsely increased CSF protein level, such as anesthetics, acetophenetidin (phenacetin), chlorpromazine (Thorazine), salicylates (aspirin), streptomycin, and sulfonamides.
- CSF chloride level determination may be invalidated by IV fluid containing chloride.
- Hyperglycemia could increase the CSF glucose level.
- Handle specimens cautiously to prevent self-contamination.
- It is recommended that lumbar punctures continue to be performed in children with first febrile convulsions, especially if less than 18 months of age.
- The total amyloid beta peptide (Abeta) protein in CSF has not been found to be a useful marker for current diagnosis of Alzheimer's disease.
- The role of routine lumbar puncture in the initial evaluation of symptom-free infants for congenital syphilis is not recommended because of the low yield of reactive VDRL in CSF and to the similar CSF leukocyte and protein values in the syphilis group and control group.