Lumbar Puncture
Marko Culjat
A. Indications
1. Initial diagnosis of central nervous system (CNS) infections.
a. Bacterial and fungal infections. The inclusion of lumbar puncture (LP) as part of sepsis workup depends on the timing of presumed sepsis (early- vs. late-onset sepsis), prematurity, maternal status (intrapartum antibiotic prophylaxis [IAP], diagnosis of chorioamnionitis), and clinical symptoms (1). While there are differing approaches among health care providers, most sources recommend the following:
In a setting of presumed early-onset sepsis, all newborns with overt signs of sepsis should undergo full evaluation, including LP.
If newborn is well appearing, but mother was diagnosed with chorioamnionitis or received inadequate IAP in a setting of prolonged rupture of membranes, LP does not need to be performed (2, 3).
In a setting of late-onset sepsis, LP is always recommended, since approximately one-third of culture-confirmed meningitis will have a negative blood culture (1). The approach of obtaining a CSF culture only if blood culture is positive is not appropriate.
In practice, these recommendations are often modified based on clinical stability of the infant (4).
b. Diagnosis of congenital infections. Diagnostic evaluations in a setting of possible congenital herpes simplex and syphilis infections are needed (5, 6). Other infections include toxoplasmosis, cytomegalovirus, and lately, Zika virus (7).
2. Monitor efficacy of meningitis treatment. While there is some controversy on whether to repeat an LP in older infants being treated for meningitis, this approach might be beneficial in VLBW infants since approximately 10% of cases have a positive repeat CSF culture despite apparently adequate antimicrobial treatment (4, 8, 9).
3. Drainage of CSF in communicating hydrocephalus associated with intraventricular hemorrhage, presenting with signs of increased intracranial pressure (ICP) or worsening ventriculomegaly (see Section B.1) (10).
a. Serial drainage of 10 to 15 mL/kg of CSF via LP for a limited number of days (usually <3) has been implemented in patients with worsening ventriculomegaly and developing signs of ICP, with cutoff values for ventricular index and diagonal ventricular size varying among practitioners (10, 11, 12, 13, 14).
b. A meta-analysis of four studies found no evidence to support repeated CSF removal in infants at risk of or developing posthemorrhagic hydrocephalus if there are no signs of increased ICP (15).
5. Diagnosis of CSF spread in patients with leukemia (18).
6. CSF instillation of chemotherapeutic agents (19).
B. Contraindications
1. Increased ICP: In the neonate with open cranial sutures, increased ICP in a setting of space-occupying intracranial lesions or meningitis rarely results in transtentorial or cerebellar herniation. However, herniation can occur after LP in the presence of elevated ICP, even when the sutures are open (20, 21). If signs of significantly increased ICP exist (rapidly declining or severely depressed level of consciousness, abnormal posturing, cranial nerve palsies, tense anterior fontanel, abnormalities in heart rate, respirations, or blood pressure without other cause), neuroimaging should be performed before LP. Open fontanels may mitigate development of papilledema until late in the clinical course (22).
2. Uncorrected thrombocytopenia or bleeding diathesis (23).
3. Infection of the skin or underlying tissue at or near the puncture site.
4. Lumbosacral anomalies, suspected or confirmed by imaging.
5. Clinical instability where risk of the procedure outweighs the benefit.
C. Equipment
All equipment must be sterile, apart from mask and cap. Prepackaged LP kits are available. Recommended equipment includes:
1. Mask, and optional cap and sterile gown
2. Sterile gloves
3. Povidone-iodine swabs (×3)
4. Aperture drape and sterile towels
5. Beveled spinal needle with stylet—usually two sizes available:
a. Small: 25 gauge, 1 inch in length
b. Large: 22 gauge, 1.5 inch in length
6. Three or more collection vials with caps
7. Adhesive bandage, gauze
D. Precautions
1. Monitor vital signs and oxygen saturation. Increasing supplemental oxygen during the procedure could prevent hypoxemia (24). However, the prudent approach would be to adjust the FiO2 to keep monitored oxygen saturation within institutional reference ranges. Avoid flexion of the neck, in either the sitting or recumbent positions, since it does not increase interspinous spaces but significantly increases the risk of airway obstruction (25, 26, 27, 28, 29). Lateral recumbent position with flexed knees has been associated with significant, but temporary desaturation episodes (28, 29).
2. Use strict aseptic technique (see Chapter 6).
3. Always use a needle with stylet while penetrating the skin, to avoid development of intraspinal epidermoid tumor (30, 31).
4. Once the needle tip is past the skin, prevent traumatic tap caused by overpenetration by advancing the needle slowly, either in a “stylet-out” or “stylet-in” technique (see Section E.9) (32, 33, 34). Topical anesthetics and eutectic mixtures applied prior to the procedure might reduce the incidence of traumatic tap (33, 34) by reducing pain (35) and struggling of the infant (36, 37). However, due to inadequate evidence regarding safety and effectiveness, no unequivocal clinical recommendations can be made (see Section E.4) (38).
5. Never aspirate CSF with a syringe. Even a small amount of negative pressure can increase the risk of intracranial subdural hemorrhage or cerebellar herniation.
6. Palpate landmarks accurately to adequately determine L3-L4 and L4-L5 interspaces (lower interspace should be used for preterm infants; see Section E.3). Mean level of termination of the spinal cord falls at the L3-L4 level at 23 to 27 gestational weeks; L3 level at 28 to 34 gestational weeks; L2-L3 level at 35 to 40 gestational weeks. The spinal cord termination level reaches mean adult levels of L1-L2 by 2 months postterm (39).
7. Communicate clearly with your assistant.
E. Technique (
Video 19.1: Lumbar Puncture)
Video 19.1: Lumbar Puncture)1. Obtain informed consent (see Chapter 3).
2. Proper positioning of the infant is key to a successful LP. The sitting position with hip flexion provides the widest interspinous spaces, with the second best position being lateral decubitus with hip flexion (25, 26, 27). Instruct the assistant to restrain the infant in the appropriate position (Figs. 19.1 and 19.2).
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