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Subject: Lumbar Puncture
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Lumbar puncture tray:
Atraumatic (Sprotte or Pajunk) needle (which has an opening on the side at the end or the needle) or the standard (Quincke) needle (which has a standard bevel) with introducer, 22 to 26 gauge
Local anesthesia for injection
Povidone-iodine or chlorhexidine (Hibiclens) for sterilization of field
Four sterile collection tubes with labels one through four
Manometer for measurement of CSF pressure if needed
Dressing to apply after procedure
Suspected central nervous system infection
Suspected subarachnoid hemorrhage
Suspected Guillain-Barré syndrome
Support for the diagnosis of pseudotumor cerebri (i.e., increased CSF pressure without infection)
Serial removal of CSF
Support for the diagnosis of multiple sclerosis (i.e., elevated IgG level and oligoclonal banding on electrophoresis)
Dermatitis or cellulitis at insertion site
Raised intracranial pressure
Supratentorial mass lesions (evaluate with CT scan first)
Severe bleeding diathesis (relative)—increased risk of epidural hematoma
Lumbosacral deformity (relative)
Pearl: Topical lidocaine (EMLA cream) has been studied in infants and found to decrease the pain response during the procedure. EMLA cream was applied in a topical dose of 1 g with an occlusion dressing placed over the site for 60 to 90 minutes before the procedure.
PITFALL: Avoid forced flexion of the neck during the procedure because cardiorespiratory arrest may occur if a child’s neck is excessively flexed.
PITFALL: Rotation of the patient beyond perpendicular can distort the appearance of the vertebral processes and make it more difficult to insert the needle in a midline position. If the patient is rotated, then insertion of the needle may be lateral and not penetrate the subarachnoid space.
Pearl: Chlorhexidine may be used for patients allergic to iodine.
PEARL: It can be helpful to palpate the back and identify landmarks before the patient is sterilely prepped and draped. Once the patient is draped, vertebral landmarks can be more difficult to identify. It can be useful to make an indention in the skin with the end of a retractable pen that has the tip retracted. This indention will not be washed away like ink when the patient is prepped with povidone-iodine or chlorhexidine.
Pearl: If bone is encountered, withdraw the needle and change the angle. Bone is usually encountered when the needle has been directed away from the midline. It can also be beneficial to palpate bony landmarks again and ensure that patient position is optimal. Patient movement during the procedure can alter the physician’s perception of the midline.
PITFALL: Make sure the bevel of the needle enters and exits the dura parallel to the long axis of the spinal column. This may lower the incidence of spinal nerve root damage and postprocedure headache.
PITFALL: Once the pop is felt, allow several seconds for the flow of CSF. The flow of CSF may not be immediate in some patients. This is especially true in dehydrated patients.
Pearl: The CSF opening pressure normal value is 6 to 14 mm Hg.
PITFALL: Have the patient relax his or her legs to prevent falsely elevating the opening pressure.
PITFALL: Accurate pressure measurements can only be made in the lateral decubitus position.
PEARL: Allow the fluid in the manometer tube to flow into the tubes first to decrease the amount of CSF removed.
PITFALL: If the tubes are not prelabeled, make sure to place the tubes in order so that you can easily identify and label each tube after the procedure.
Implantation of epidermoid tumors, which occur when epidermoid tissue is implanted into the spinal canal during a lumbar puncture: This occurs with the use of unstyletted needles or with needles that have poorly fitting stylets. These tumors cause pain to the back and lower extremities years after spinal puncture.
Aspiration of a nerve root into the spinal space, which occurs when the needle is withdrawn without the stylet in place.
Headache occurs in 5% to 40% of all lumbar punctures.
Headaches can start up to 48 hours after the procedure and usually last 1 to 2 days (sometimes up to 14 days).
Headache is associated with sitting upright and ceases with lying down.
They are thought to be caused by leakage of fluid through the dural puncture site.
Incidence of headache may be higher with “cutting needles” and larger-diameter needles.
Epidural blood patch may be performed to alleviate a persistent headache. This procedure is usually performed by an anesthesiologist.
Infection of CSF:
Infection on CSF may occur if local tissue infection is present over the LP site. Overlying cellulitis is a contraindication to LP.
It has also been suggested that infection may be caused by introduction of bacteria from infected blood (sepsis or bacteremia) during an LP. This has not been proven, and reported cases most likely represent CSF infection that was not yet detectable at the time of LP.
This occurs in 2% to 3% of patients after LP.
Onset of symptoms is noted within 12 hours of procedure and manifested by loss of consciousness.
Many of these patients have a normal CSF opening pressure.
Most patients improve within 48 hours of symptom onset.
Risk of this complication can be decreased with the use of small-caliber spinal needles and ICP-lowering agents when needed.
Backache and radicular symptoms: Minor backache occurs in up to 90% of patients because of local trauma of the spinal needle.
Use Gram stain, culture, glucose, protein, and lactate dehydrogenase (LDH).
Other tests that may be performed are CSF counterimmunoelectrophoresis (CIE), CSF latex agglutination (LA), and coagulation immunoelectrophoresis.
Commercial kits are available to detect the many common organisms that cause meningitis.
All of these tests have a low sensitivity for bacterial meningitis; however, they have a much higher specificity. False-negative antigen tests may be seen with elevated rheumatoid factor and complement levels.
Polymerase chain reactions hold promise for future rapid diagnosis of infection and may be available in some hospital settings.
CSF should be examined for xanthochromia, which is produced by the lysis of red blood cells (RBCs) in the CSF. RBC lysis begins to occur approximately 2 hours after exposure to CSF. The CSF is centrifuged and then examined for clarity. Collection of CSF within 12 hours of symptom onset of suspected subarachnoid hemorrhage may reveal false-negative results as a result of this phenomenon.