INTRODUCTION — Examination of the cerebrospinal fluid (CSF) provides essential diagnostic information in many clinical situations. The indications, contraindications, and procedure for performing a lumbar puncture (LP) in children are presented here.
LP in adults, the physiology and utility of examination of CSF, and the diagnosis, prevention, and treatment of postspinal headache are discussed separately:
●(See "Lumbar puncture: Technique, indications, contraindications, and complications in adults" and "Cerebrospinal fluid: Physiology and utility of an examination in disease states" and "Post dural puncture headache".)
●(See "Cerebrospinal fluid: Physiology and utility of an examination in disease states".)
●(See "Post dural puncture headache".)
ANATOMY — During LP, a styletted needle is passed between the interspinous processes of the lumbar vertebrae and through the supraspinal and intraspinal ligaments, ligamentum flavum, dura mater, and arachnoid mater into the subarachnoid space. Cerebrospinal fluid (CSF) is then removed for sample.
LP should be performed distal to the spinal cord, at the level of the cauda equina (figure 1). At birth, the inferior tip of the spinal cord is located opposite the body of L3. The vertebral column grows more rapidly than the spinal cord. As a result, by adulthood, the tip of the spinal cord is at the inferior border of the body of L1. In older children, LP can be performed from the L2-L3 interspace to the L5-S1 interspace because these interspaces are below the termination of the spinal cord. LP in children younger than 12 months must be performed below the L2-L3 interspace [1].
An imaginary line that connects the two posterior-superior iliac crests intersects the spine at approximately the fourth lumbar vertebra (figure 2). This landmark helps to locate the L3-L4 and L4-L5 interspaces.
INDICATIONS — Major indications for LP in children are as follows:
●Suspected central nervous system (CNS) infection – For children, evaluation of cerebrospinal fluid (CSF) for possible CNS infection remains the most common emergency indication for LP. Because delay in the administration of appropriate antimicrobial therapy can have deleterious effects on outcomes for patients with CNS infections, early empiric antimicrobial treatment is recommended. Such treatment should not be delayed when LP cannot be performed in a timely fashion (eg, when patients have contraindications to LP or when concern for increased intracranial pressure (ICP) or a space-occupying intracranial lesion mandates neuroimaging prior to the procedure). However, other cultures or testing necessary to diagnose the type of infection should be obtained prior to antimicrobial therapy whenever possible. (See "Viral meningitis in children: Clinical features and diagnosis", section on 'Cerebrospinal fluid studies' and "Bacterial meningitis in children older than one month: Clinical features and diagnosis", section on 'Evaluation'.)
●Suspected subarachnoid hemorrhage – Evaluation for spontaneous subarachnoid hemorrhage is a less common emergency indication for LP in children. A computed tomography (CT) scan should be performed initially for all children with findings suspicious for subarachnoid hemorrhage (eg, sudden onset of severe headache, which may or may not be accompanied by meningismus, neck pain, or preretinal hemorrhages). LP to assess for elevated opening pressures, red blood cells in the CSF that do not clear during collection, and xanthochromia is indicated when clinical suspicion remains high but subarachnoid hemorrhage is not seen on CT. (See "Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis", section on 'Evaluation and diagnosis'.)
●Other – Other pediatric indications for LP include:
•Measurement of opening pressure and removal of CSF for the diagnosis and treatment of idiopathic intracranial hypertension (pseudotumor cerebri) (see "Idiopathic intracranial hypertension (pseudotumor cerebri): Clinical features and diagnosis")
•Diagnosis of neurologic conditions such as Guillain-Barré syndrome or juvenile multiple sclerosis (see "Guillain-Barré syndrome in children: Epidemiology, clinical features, and diagnosis", section on 'Cerebrospinal fluid' and "Pathogenesis, clinical features, and diagnosis of pediatric multiple sclerosis", section on 'Cerebrospinal fluid analysis')
•Diagnosis of pediatric metabolic disease (see "Inborn errors of metabolism: Identifying the specific disorder", section on 'Laboratory evaluation')
•Instillation of chemotherapy for intrathecal treatment or prevention of CNS malignancy (see "Overview of the management of central nervous system tumors in children", section on 'Chemotherapy' and "Treatment of acute lymphoblastic leukemia/lymphoma in children and adolescents", section on 'CNS management')
•Spinal anesthesia (see "Spinal anesthesia: Technique")
CONTRAINDICATIONS — Potential contraindications to LP include:
●Increased intracranial pressure (ICP) — Children with elevated ICP are at risk for cerebral herniation when an LP is performed [1,2]. Consequently, in children with clinical suspicion for elevated ICP based upon physical examination or predisposing illness, LP should not be performed until neuroimaging is performed to identify cerebral edema, space-occupying lesion, or obstructive hydrocephalus, any one of which would contraindicate the procedure [3]. (See 'Preprocedure evaluation' below and 'Cerebral herniation' below.)
Furthermore, normal neuroimaging does not absolutely exclude the presence of elevated ICP or the possibility that elevated ICP will develop at a later time. Nevertheless, LP can usually be safely performed within six hours of a normal CT scan when no other contraindications are present.
●Respiratory distress — Children with respiratory compromise may become hypoxemic or apneic while undergoing LP, especially in the lateral recumbent position [3]. Thus, careful assessment and support of airway and breathing should be provided, as needed, before and during the procedure in patients with significant respiratory distress. Patients who cannot maintain their airway or who are in respiratory failure should undergo endotracheal intubation prior to LP.
●Hemodynamic instability — Children with shock should undergo appropriate resuscitation before LP. As an example, a hemodynamically unstable patient with septic shock who may have bacterial meningitis should undergo emergency fluid resuscitation, have a blood culture obtained, and receive empiric antibiotics as soon as possible; LP should be deferred until the child's condition stabilizes.
●Soft tissue infection at the puncture site — Meningitis or other infections such as epidural abscess, vertebral osteomyelitis, discitis, or intramedullary spinal abscess can be induced if the LP is performed through cellulitis or soft tissue infection (eg, epidural abscess) at the site of puncture [4-6]. For this reason, local infection at the puncture site is a contraindication to performing LP.
●Bleeding disorder — Because of the risk of spinal hematoma formation, we generally do not advise performing LP in patients with coagulation defects who are actively bleeding, have severe thrombocytopenia (eg, platelet counts <50,000/microL), or have an international normalized ratio (INR) >1.4 without correcting the underlying abnormalities. When LP is considered essential for a patient with an abnormal INR or platelet count in whom the cause is not obvious, we suggest consultation with a hematologist to provide the best advice for safe correction of the coagulopathy prior to performing the LP. In cases in which LP is considered necessary but the risk of bleeding is considered to be high, it may be useful to perform the procedure under fluoroscopy or ultrasound guidance to reduce the chance of accidental injury to small blood vessels.
Evidence regarding the safety of performing LP in patients with thrombocytopenia or coagulation factor deficiency is limited:
•The safety of performing LP in children with thrombocytopenia at the time of diagnosis or during treatment for acute lymphoblastic leukemia was reported in two retrospective series describing 5223 and 9088 LPs, of which 941 [7] and 266 [8], respectively, were performed in children with a platelet count <50,000/microL. No serious hemorrhagic complications occurred. However, the number of children with platelet counts <10,000/microL was small in both studies, making the safety of performing LP without giving a platelet transfusion uncertain at these low levels.
•No serious complications were reported in a small retrospective series describing children and adults with hemophilia who received LP following replacement of the deficient factor [9].
PREPARATION
Preprocedure evaluation — Circumstances that should be identified in preparation for LP include the following:
●Critically ill children who require monitoring of oxygen saturation, respirations, and heart rate during the procedure, especially those with respiratory distress or hemodynamic instability that require stabilization before LP.
●Children who may have increased intracranial pressure (ICP) and should have neuroimaging performed before LP based upon any one of the following physical findings [3,10]:
•Bradycardia with hypertension
•Altered mental status
•Unequal, dilated, or poorly responsive pupils
•Papilledema
•Focal neurologic findings
•Decorticate or decerebrate posturing
•At risk for brain abscess (immunocompromise or congenital heart disease with a right-to-left shunt)
If meningitis or encephalitis is suspected, the clinician should obtain appropriate cultures (eg, blood, urine, and/or tissue cultures) and initiate antimicrobial therapy prior to neuroimaging.
●Signs of infection of the skin or soft tissues in the lumbar region. (See 'Contraindications' above.)
●Patients with spinal abnormalities (such as spina bifida or severe scoliosis) should be identified. An alternative approach for obtaining cerebrospinal fluid (CSF), such as performing the procedure under fluoroscopy, may be required for such patients [1,11]. Patients who have undergone posterior lumbar spinal fusion cannot have spinal fluid obtained by LP. Such patients need to undergo an alternative method for CSF collection (eg, cisternal or transforaminal tap); this procedure should be performed by a neurosurgeon or neuroradiologist.
Patient counseling — Although LP is a relatively simple and safe procedure to perform, it is frightening for most children and their families. A clear explanation of the urgent indications for the procedure, as well as the details of the procedure itself, is usually reassuring and should routinely be provided. In addition, it may be helpful for older children and adolescents to "practice" the position that they will assume for the procedure.
In addition, written informed consent is advisable given the invasive nature of the procedure and the rare but potentially severe complications that can occur. Justification for and essential components of informed consent in the pediatric emergency department are described in the reference [12].
In the emergency setting, LP is performed primarily to identify central nervous system (CNS) infection or subarachnoid hemorrhage, conditions that must be urgently diagnosed and treated (see 'Indications' above). Consequently, the benefit of early diagnosis far outweighs the risks of the procedure for patients who have been carefully screened for contraindications. (See 'Contraindications' above.)
Equipment — Commercial trays are available for performing LP and typically contain all of the necessary equipment except topical antiseptic solution, sterile gloves, and manometers. The following equipment is needed if a commercial tray is not available:
●Lidocaine 1 percent without epinephrine and topical anesthetic cream (such as liposomal lidocaine or eutectic mixture of lidocaine 2.5 percent and prilocaine 2.5 percent)
●Sterile 3-mL syringe with 25-gauge needle for lidocaine injection
●Four sterile collecting tubes
●Sterile gloves for all patients
●Surgical mask or face shield for all patients
●For patients who pose an infection control risk, other personal protective equipment as indicated based upon type of infectious transmission (eg, contact, droplet, or airborne)
●Sterile drapes
●Povidone-iodine solution or similar antiseptic solution (eg, 2 percent chlorhexidine gluconate in 70 percent isopropyl alcohol)
●Sterile sponges or 4x4 gauze pads for preparing puncture site
●Manometer (typically used in patients older than two years of age)
●22-gauge styletted spinal needle. The following guidelines for appropriate needle length are based on the child's age (although a longer needle may be necessary for children who are large for their age, particularly for those closer to 12 years):
•Under 2 years: 1.5 inches (3.75 cm)
•Between 2 and 12 years: 2.5 inches (6.25 cm)
•Over 12 years: 3.5 inches (8.75 cm)
●Resuscitation equipment (eg, a code cart with emergency airway, breathing, and circulation supplies) should be immediately available for all patients.
Analgesia and sedation — Options for local anesthesia in infants and children undergoing LP include infiltration with lidocaine, needle-free lidocaine delivery, and/or topical preparations (such as EMLA or LMX) (see "Subcutaneous infiltration of local anesthetics" and "Clinical use of topical anesthetics in children"). Each has its advantages and disadvantages:
●Infiltration with lidocaine provides immediate analgesia but may obscure bony landmarks in neonates and young infants, making the procedure more difficult to perform. Ultrasound guidance may mitigate this problem. (See 'Ultrasound guidance' below.)
●Topical anesthetics anesthetize the skin (but not the subcutaneous tissues) without altering landmarks but require 30 to 60 minutes to be effective, depending on the preparation. Thus, they are only useful for elective LP. The dose and precautions for specific topical anesthetics and their use in neonates are discussed separately. (See "Clinical use of topical anesthetics in children" and "Prevention and treatment of neonatal pain".)
For older infants and children, more complete local anesthesia may be provided by the combination of a topical and infiltrated local anesthetic.
For neonates, oral sucrose appears to be safe and is easy to administer. Thus, offering sucrose to infants less than six months of age undergoing LP who are not restricted from oral intake, in addition to local anesthesia, is an option. (See "Pharmacologic agents for pediatric procedural sedation outside of the operating room", section on 'Analgesic agents' and "Prevention and treatment of neonatal pain".)
For older infants and children who are unable to cooperate with positioning and restraint during the procedure, mild procedural sedation (eg, midazolam alone) reduces anxiety and, in combination with local anesthesia, typically permits safe performance of the LP. Otherwise, moderate procedural sedation may be used. (See "Procedural sedation in children outside of the operating room" and "Selection of medications for pediatric procedural sedation outside of the operating room", section on 'Sedation for painful procedures'.)
Evidence from randomized trials in neonates demonstrates that both infiltrative and topical anesthesia reduce the pain associated with LP [13,14]. The use of an infiltrative anesthetic does not appear to interfere with obtaining CSF in infants and small children [13-15]. Furthermore, observational evidence suggests that using a local anesthetic increases the likelihood of a successful procedure:
●Among 297 infants ≤3 months of age receiving LPs in an emergency department, LPs performed with a local anesthetic were twice as likely to be successful as those performed without local anesthesia (odds ratio [OR] 2.2, 95% CI 1.04-4.6) [16].
●In a prospective series describing 1459 children receiving LPs in an emergency department, procedures performed without local anesthetic were more likely to be traumatic or unsuccessful than those performed with local anesthesia (OR 1.6, 95% CI 1.1-2.2) [17].
These findings suggest that local anesthesia should be provided for all children whenever possible. We suggest topical anesthesia for all neonates and young infants for whom the procedure can safely be delayed until the medication has had an effect. When there is not enough time for topical anesthesia, an infiltrative anesthetic is suggested for most; the available data do not support the notion that infiltrative anesthetics interfere with the procedure, even in this young age group.
Positioning — Careful positioning is required in order to accurately identify landmarks and successfully perform the LP. An experienced assistant must be available to hold the child in an optimal position. Children should be observed for adequate respiratory function throughout the procedure because positioning may compromise respiratory status; apnea can occur, especially in young infants. The lateral recumbent or the sitting position can be used as described below.
Lateral recumbent — For the lateral recumbent position (figure 2 and picture 1), the clinician and an assistant place the child on their side near the edge of the examining table. The assistant then helps the child draw the knees upward and flex the neck. This position can be accomplished if the assistant places one arm around the posterior aspect of the child's neck and the other arm under the child's knees. The assistant can maintain adequate restraint by holding onto his or her own wrists.
Satisfactory positioning also requires the following:
●The child's hips and shoulders should be kept perpendicular to the examining table in order to maintain spinal alignment without rotation.
●The gluteal crease must be aligned with the spinous processes.
Because neck flexion in the lateral recumbent position may not significantly change the interspinous space as determined by ultrasound measurement [18], it may be omitted in the cooperative child. However, careful neck flexion is still often necessary to prevent movement in the infant or young child.
Sitting — The sitting position may be preferred in children who have the potential for developing respiratory compromise because of hyperflexion of the neck in the lateral recumbent position (figure 3) [19,20]. In addition, this position may improve flow of CSF in very small infants (less than two weeks of age). The sitting position does not permit accurate measurement of opening pressure and should be avoided when manometry is necessary. (See 'Use of manometer' below.)
Infants can be held in the sitting position by an assistant who grasps one of the infant's arms and one of the legs in each hand, while supporting the head to prevent excessive flexion at the neck (figure 3).
Older children should be asked to sit with their legs hanging over the edge of the examining table (picture 2). They can then be flexed over a pillow with the elbows resting on the knees. An assistant should maintain alignment throughout the procedure, even in a cooperative child.
Monitoring — Monitoring appropriate to the degree of illness should be performed throughout the procedure. In addition, the assistant holding the child and the clinician performing the procedure should monitor visual respirations. Because of the higher risk of apnea, we suggest that all young infants undergo continuous cardiorespiratory monitoring and pulse oximetry during LP.
PROCEDURE
Ultrasound guidance — Prior to performing an LP in children and whenever properly trained providers are available, we suggest that static bedside ultrasound be used to identify the best site and safest depth (picture 3 and image 1). In a meta-analysis of 12 randomized trials of static bedside ultrasound guidance for LP in a total of 956 pediatric and adult patients, first-pass success rate was more likely when ultrasound guidance was used compared with a landmark-based technique (risk difference 9 percent, 95% CI 1-17 percent) [21]. Furthermore, ultrasound guidance significantly decreased the number of needle passes or traumatic taps and reduced reported pain. Subgroup analysis of the six pediatric studies (456 children) found that the first-pass success rate was higher when ultrasound guidance was used, but the result was not significant (risk difference 12 percent, 95% CI -10 to 34 percent); fewer traumatic taps occurred when ultrasound guidance was used in children (risk difference -21 percent, 95% CI -38 to -4 percent). Risk of bias was low for most of the included studies, but there was significant heterogeneity seen in the meta-analyses.
Thus, when performed by an experienced provider, static ultrasound is a useful tool in obtaining cerebrospinal fluid (CSF) in children. For infants, the technique of static ultrasound to mark the best site and determine the needle depth prior to LP is described in the reference [22]. LP in adults is discussed separately. (See "Lumbar puncture: Technique, indications, contraindications, and complications in adults", section on 'Ultrasound'.)
Lumbar puncture — LP should be performed with universal precautions and sterile technique. Personal protective equipment should be donned, as indicated based upon type of infectious transmission (eg, contact, aerosol, or airborne), for patients who pose an infection control risk.
Procedural steps include:
●Identify and mark the interspace (L3-L4 or L4-L5) through which the LP will be performed. An imaginary line that connects the two posterior-superior iliac crests intersects the spine at approximately the fourth lumbar vertebra and helps to locate the interspace (figure 2). When available, ultrasound guidance further delineates the best site and proper depth of needle insertion. (See 'Ultrasound guidance' above.)
●Using sterile technique, clean the puncture site with povidone-iodine solution or other appropriate site preparation solution, such as 2 percent chlorhexidine gluconate in 70 percent isopropyl alcohol. The clinician should clean the site of puncture first and then expand with circular movements of increasing circumference. The area cleansed should be large, including the posterior superior iliac spine, which may be palpated as a landmark during the procedure. The clinician may remove the solution with isopropyl alcohol.
●Place one set of sterile drapes underneath the patient and use a surgical drape with an eyehole to cover above and around the puncture site. Alternatively, the clinician may choose to proceed without the surgical drape in order to better maintain visualization of the vertebral bodies above and below the puncture site during the procedure. For infants, use a neonatal LP tray whenever available. The neonatal LP tray supplies a small drape appropriate for use in infants and permits visualization of respirations throughout the procedure. If a neonatal LP tray is not available, fold the surgical drape to permit visualization of respirations throughout the procedure. Place the drape such that the anterior superior iliac spine is covered for palpation of the landmarks as needed by the gloved hand.
●For children receiving infiltrative anesthesia, the skin and subcutaneous tissues are anesthetized with 1 percent lidocaine using a 25-gauge needle to raise a wheal over the interspace and then to infiltrate the deeper subcutaneous tissue. In order to adequately infiltrate the deeper tissues for larger children, the 25-gauge needle should be replaced with a longer needle once the skin is anesthetized. During infiltration, the clinician should aspirate before infiltrating, especially when anesthetizing the deeper tissues, to be sure that the needle is not inadvertently placed in the subarachnoid space.
●Placing the spinal needle in the subarachnoid space:
•Check the spinal needle to ensure that the stylet is firmly in place.
•Hold the spinal needle with one or both hands, depending upon clinician preference and experience (figure 4). In the single-hand approach, use the free thumb tip as a guide by holding it on the spinous process above or below the desired interspace entry site. With the two-handed approach, support the needle between the index fingers while stabilizing the hub with the thumbs.
•Position the spinal needle in the midline. If using a cutting spinal needle (eg, Quincke or Atraucan needle), orient the bevel parallel to the direction of the dural fibers (eg, bevel up for patients in the lateral decubitus position and 90 degrees to either the left or right side for patients in the sitting position). This approach separates rather than cuts the longitudinally running dural fibers and thereby decreases CSF leakage after the procedure is completed [23].
Atraumatic spinal needles (ie, pencil-point needles such as Sprotte or Whitacre needles) do not require any special orientation.
•Advance the needle slowly through the spinous ligaments, aiming cephalad toward the umbilicus. Based upon ultrasound measurements, the angle of entry in children in the lateral recumbent position is approximately 45 degrees from perpendicular in infants under 12 months of age and about 30 degrees from perpendicular in children over 12 months of age [24].
•Because penetration of the dura is not always obvious and the depth to which the needle must be inserted varies depending on the size of the patient and body habitus, remove the stylet cautiously from time to time as the needle is advanced to look for CSF. A "pop" often is perceived as the needle penetrates the dura and enters the subarachnoid space. At this point, remove the stylet, place it on a sterile surface, and assess for CSF at the hub with free flow.
Some clinicians prefer to remove the stylet once the skin has been punctured and to advance the needle without the stylet into the subarachnoid space. The goal of this approach is to enhance the likelihood of obtaining CSF, particularly for small infants [25]. In observational reports, rates for successful and nontraumatic LPs were improved using this technique [16,17].
•When CSF return occurs, attach the manometer and measure the opening pressure (children in whom a reliable measurement can be obtained) and then collect CSF for analysis. (See 'Use of manometer' below and 'Cerebrospinal fluid collection' below.)
•Once CSF is collected, replace the stylet and remove the needle. Wash the antiseptic solution off the skin and place a sterile adhesive bandage or gauze dressing over the puncture site.
Use of manometer — The opening pressure should be measured with manometry whenever possible. Because the measurement may be unreliable, opening pressure measurement may be deferred in infants younger than two years of age, struggling or uncooperative patients, or LPs performed with the patient in the sitting position.
●The manometer is attached to the spinal needle hub with a three-way stop-cock (figure 5).
●CSF is permitted to enter the manometer; opening pressure is recorded at the highest level attained by the CSF in the manometer column, ideally with the legs in extension. The CSF level fluctuates slightly with respiratory and cardiac cycles. The presence of these fluctuations confirms placement of the spinal needle in the subarachnoid space. The absence of fluctuations may indicate that the needle is partially occluded by dura or a nerve root, and the reading may be inaccurate.
●Normal opening pressures range from 5 to 20 cm H2O in a relaxed patient in the lateral recumbent position with the neck and legs extended. The range can increase to 10 to 28 cm H2O in patients in the lateral recumbent position with the neck and legs flexed [26,27].
●After the opening pressure has been measured, the stop-cock can be used to transfer fluid from the manometer column to sterile tubes.
Cerebrospinal fluid collection — The CSF should be collected in three to four sterile tubes. Approximately 1 mL of CSF per tube is needed for standard studies. The first tube should be sent for Gram stain and bacterial culture, the second for CSF glucose and protein, and the third for CSF cell count and differential. Additional tubes may be saved for future studies or used for viral culture, fungal culture, cell pathology, or special chemistries. If subarachnoid hemorrhage is suspected, four tubes should be collected and the first and fourth tubes sent for cell count.
The interpretation of CSF testing is discussed separately. (See "Cerebrospinal fluid: Physiology and utility of an examination in disease states" and "Bacterial meningitis in children older than one month: Clinical features and diagnosis", section on 'Interpretation'.)
TROUBLESHOOTING
Bony resistance — Bony resistance occasionally is felt during attempted LP. Immediate bony resistance is probably due to puncture over the posterior spinous process; it can be overcome by withdrawing the needle to the subcutaneous tissue, confirming that the position of the spine is not rotated, and palpating again to make sure that the puncture site is in the midline. Bony resistance also may be caused by the inferior spinous process; this resistance can be overcome by repositioning the child to ensure the presence of adequate flexion, particularly at the hips, to open the interlaminar space and by redirecting the spinal needle more sharply cephalad [28].
Poor flow — The following techniques can be attempted to improve the flow of cerebrospinal fluid (CSF) [1]:
●Rotating the spinal needle by 90 degrees
●Replacing the stylet and advancing the needle slightly
●Pulling the needle back to the subcutaneous tissue and redirecting
●Removing the spinal needle and attempting the procedure at a different site; a new needle should be used for each additional attempt, if the needle has been removed completely
Change in position from lateral recumbent to sitting is sometimes suggested to enhance flow, but we do not use this approach because movement of the patient risks dislodgement of the spinal needle, and evidence is lacking to indicate that this approach results in more rapid CSF flow. In addition, intracranial pressure (and therefore CSF flow) in normal patients relies primarily on venous pressure and not posture [29]. Thus, CSF may be collected in either the sitting or lateral recumbent position. For an individual patient, the rate of CSF flow would not be expected to be different when comparing one position with the other.
Similarly, for the dehydrated infant undergoing LP, limited evidence suggests that intravenous rehydration does not appear to increase the volume of CSF in the subarachnoid space and may not improve the success rate of LP [30]. However, intravenous fluids should be given to stabilize patients in shock before performing a LP.
Traumatic puncture — A traumatic puncture occurs when the spinal needle strikes the venous plexus that encircles the spinal cord as it advances into the subarachnoid space. This problem can arise if the spinal needle is not directly in the midline or has been placed too deep and passed through the posterior wall of the dura into the internal (ventral) vertebral venous plexus (figure 6). The CSF typically clears as it is collected if the spinal needle is in the subarachnoid space. The spinal needle should be removed if the bloody fluid clots in the hub or does not clear; these events are indications that the needle is in an improper position. The LP should be reattempted, with a new needle, at a different site.
Trauma from the LP can cause small amounts of bleeding into the CSF that can interfere with interpretation of the CSF cell count. How to account for this possibility is discussed elsewhere. (See "Cerebrospinal fluid: Physiology and utility of an examination in disease states", section on 'Predicted WBC count after traumatic tap'.)
Lateral approach — The midline approach usually is preferred in pediatrics. However, a lateral or paramedian approach is acceptable (figure 7). In the lateral approach, the needle is inserted 10 to 15 degrees lateral to the upper border of the L3 or L4 spinous process. The needle is then directed slightly medially and cephalad.
The lateral approach bypasses the supraspinal ligament and penetrates the ligamentum flavum, passing through the dura into the subarachnoid space.
POST-PROCEDURAL COMPLICATIONS — LP is a relatively safe procedure, but minor and major complications can occur even when standard infection control measures and good technique are used. Postspinal headache and localized back pain are the most commonly reported minor complications after LP in children. Major complications are rare but include cerebral herniation, infection (eg, bacterial meningitis or epidural abscess), spinal hematoma, nerve root damage, or later development of an epidermoid tumor.
Cerebral herniation — The most serious complication of LP is cerebral herniation. This can occur when LP is performed in a patient with increased intracranial pressure (ICP) and an abnormal ICP gradient (eg, space-occupying lesion such as a brain tumor or abscess with a midline shift or obstructive hydrocephalus). In these patients, LP lowers pressure caudally and causes the intracranial contents to shift down the pressure gradient [31]. Neuroimaging should be performed before LP to exclude such lesions in children with signs suggesting increased risk for cerebral herniation, including altered mental status, papilledema, and focal neurologic findings. (See 'Preprocedure evaluation' above and "Elevated intracranial pressure (ICP) in children: Clinical manifestations and diagnosis".)
By contrast, children with uniform increased ICP (eg, idiopathic increased ICP [pseudotumor cerebri]) may safely undergo LP. Elevation of cerebrospinal fluid (CSF) opening pressure in the absence of pleocytosis is an essential element of diagnosis in these patients. (See "Idiopathic intracranial hypertension (pseudotumor cerebri): Clinical features and diagnosis", section on 'Lumbar puncture'.)
For children, concern regarding herniation following LP arises most frequently in patients with suspected bacterial meningitis. In one retrospective review of 445 children hospitalized with bacterial meningitis, cerebral herniation occurred in 19 (4.3 percent); 12 of the episodes occurred within the first 12 hours after LP was performed [32]. However, a review of the literature found that herniation was unlikely in children with bacterial meningitis unless they had focal neurologic findings or coma; furthermore, a normal CT scan does not absolutely exclude subsequent herniation [33].
Infection — Meningitis or other infections such as epidural abscess, vertebral osteomyelitis, discitis, or intramedullary spinal abscess can be induced if the LP is performed through cellulitis or soft tissue infection at the site of puncture [4-6]. For this reason, local infection at the puncture site is a contraindication to performing LP. Otherwise, with proper sterile technique, the risk of causing meningitis is extremely low in the absence of soft tissue infection at the puncture site.
Spinal hematoma — Spinal hematoma is a complication after LP that usually occurs in patients with uncorrected bleeding disorders, but it has also been reported in those with no apparent risk factors for bleeding [34]. (See 'Contraindications' above.)
The diagnosis of spinal hematoma is complicated by the concealed nature of the bleeding; thus, a high index of suspicion must be maintained. Patients who have back pain that is associated with neurologic findings (eg, weakness, decreased sensation, or incontinence) after undergoing LP require emergency evaluation for possible spinal hematoma.
The appropriate treatment for the symptomatic patient is prompt surgical intervention, usually a laminectomy, and evacuation of the blood. Timely decompression of the hematoma is essential to avoiding permanent loss of neurologic function.
Postspinal headache — Postspinal headache is one of the most common complications of LP. Limited evidence suggests that the frequency of postspinal headaches in children is approximately 5 to 15 percent [35-41]. Various techniques such as using the smallest possible needle, using atraumatic needles, and, when using a cutting needle, placing the bevel of the needle parallel to the long axis of the spine have been shown to prevent or lessen postspinal headache. (See "Post dural puncture headache", section on 'Procedural risk factors'.)
By contrast, bed rest or prolonged supine position does not appear to prevent headache in children. As an example, in one randomized trial comparing bed rest for 24 hours with free mobility following LP in 111 children, positional headaches were more likely with bed rest than with no limitations on activity (15 versus 2 percent, respectively) [42]. In a separate trial of 400 infants and young children undergoing LP, the frequency of post-spinal headache was similar for individuals who remained flat for 30 minutes compared with those who remained flat for four hours (approximately 7 percent in both groups) [41]. In this study, the presence of headache in infants was based upon a validated pain score administered by nurse observers.
The treatment of postspinal headache is discussed in detail separately. (See "Post dural puncture headache", section on 'Treatment'.)
Back pain — Observational studies suggest that back pain occurs in up to 11 percent of children following LP [41,43]. Back pain typically resolves within a few days of the procedure. Prolonged pain should raise concern for a localized infection or a spinal hematoma. (See 'Infection' above and 'Spinal hematoma' above.)
In addition, transient, unilateral radicular pain radiating to the posterior leg may be reported by verbal patients during the procedure if the spinal needle contacts one of the nerves. Reversible low-pressure radiculopathy ("pseudo-tethered cord") has also been described [44]. However, sustained radicular pain due to nerve injury is rare.
Epidermoid tumor — The formation of an epidermoid spinal cord tumor is a rare complication of LP that may become evident years after the procedure is performed [45-49]. It is believed to be caused by epidermoid tissue that is transplanted into the spinal canal during LP without a stylet, or with one that is poorly fitting. For this reason, spinal needles with tight-fitting stylets should always be used during LP [50,51]. (See 'Lumbar puncture' above.)
FOLLOW-UP CARE — No specific follow-up care is required for children who have had a LP. Bed rest is of no apparent benefit. (See 'Postspinal headache' above.)
Patients may receive analgesia with acetaminophen or ibuprofen. They should seek medical attention for worsening headache or back pain, or for leg pain, paresthesias, or weakness.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Post dural puncture headache".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Lumbar puncture (spinal tap) (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Indications – In children, primary emergency indications for lumbar puncture (LP) consist of the diagnosis of central nervous system (CNS) infection or, less commonly, subarachnoid hemorrhage. LP is also used for diagnostic testing (eg, suspicion for idiopathic intracranial hypertension, Guillain-Barré, juvenile multiple sclerosis, or metabolic disease), administration of intrathecal medications, and spinal anesthesia. (See 'Indications' above.)
●Contraindications – Prior to performing an LP, the clinician should assess for potential contraindications including signs of increased intracranial pressure (ICP), respiratory distress, hemodynamic instability, skin or soft tissue infection at the puncture site, or bleeding disorder. (See 'Contraindications' above.)
●Preprocedure evaluation – Preprocedure evaluation should determine the need for stabilization and neuroimaging prior to LP as well as the presence of spinal abnormalities(see 'Preprocedure evaluation' above):
•Signs of increased ICP – Children should have neuroimaging performed before LP if there are findings of increased ICP, including any one of the following:
-Bradycardia with hypertension
-Altered mental status
-Unequal, dilated, or poorly responsive pupils
-Papilledema
-Focal neurologic findings
-Decorticate or decerebrate posturing
-At risk for brain abscess (immunocompromise or congenital heart disease with a right-to-left shunt)
If meningitis or encephalitis is suspected, the clinician should obtain appropriate cultures (eg, blood and urine cultures) and initiate antimicrobial therapy prior to neuroimaging.
•Critically ill patients – Children who are critically ill should undergo stabilization of airway, breathing, and circulation prior to LP and have cardiorespiratory monitoring during LP. Because of the higher risk of apnea, we suggest that all young infants also undergo continuous cardiorespiratory monitoring and pulse oximetry during LP.
•Patients with spinal abnormalities – Patients with spinal abnormalities (such as spina bifida or severe scoliosis) should be identified. An alternative approach for obtaining cerebrospinal fluid (CSF), such as performing the procedure under fluoroscopy, may be required for such patients. Patients who have undergone posterior lumbar spinal fusion cannot have spinal fluid obtained by LP.
●Analgesia and sedation – LP is a painful procedure that warrants appropriate local anesthesia and, in uncooperative patients, mild or moderate sedation (see 'Analgesia and sedation' above):
•We suggest topical anesthesia for neonates and young infants for whom LP can safely be delayed until the medication has had an effect (Grade 2C). In addition, we suggest that most neonates and small infants receive infiltrative anesthetics. (See 'Analgesia and sedation' above and "Clinical use of topical anesthetics in children".)
•We suggest that older infants and children receive a combination of a topical and infiltrative anesthetic (Grade 2C). The latter can be used alone when the LP must be performed urgently.
•We suggest offering sucrose for analgesia to infants younger than six months of age who are not restricted from oral intake (table 1) (Grade 2C). (See "Pharmacologic agents for pediatric procedural sedation outside of the operating room", section on 'Analgesic agents'.)
●Ultrasound guidance – Prior to performing an LP in children and whenever properly trained providers are available, we suggest that static bedside ultrasound be used to identify the best site and safest depth (picture 3 and image 1). (See 'Ultrasound guidance' above.)
●Procedure – Key steps in the successful and safe performance of an LP include (see 'Procedure' above):
•Identifying and marking the site of the puncture
•Careful positioning of the patient in the lateral recumbent (figure 2 and picture 1) or sitting position (picture 2 and figure 3)
•Use of sterile technique
•Proper orientation of the spinal needle during the procedure (figure 4)
Troubleshooting for commonly encountered difficulties during LP is provided. (See 'Troubleshooting' above.)
●Complications – Postspinal headache and localized back pain are the most commonly reported minor complications after LP in children. Major complications are rare but include cerebral herniation, paraspinal infection, spinal hematoma, or later development of an epidermoid tumor. (See 'Post-procedural complications' above.)
