Question 1: For pediatric lumbar punctures (LPs), does advancement of the LP needle without a stylet (ie, stylet out) increase the odds of a successful LP?

Advancement of the LP needle without a stylet has been reported in the adult medical literature since the 1960s.¹ After puncturing through the epidermis and subcutaneous tissue with the stylet in place, does advancement with the stylet out allow for earlier recognition of the subarachnoid space, or would the soft pediatric bony structures more easily facilitate materials occluding the needle?

A 17-month prospective observational study in 2006 by Baxter et al evaluated 594 pediatric LPs in children age 12 months or younger in a tertiary pediatric emergency department.² Of 594 pediatric LPs, data were collected on 428 (72 percent), of which 377 were performed by residents and included in their analysis.

The authors were interested in resident-performed LPs. LP kits included a form for recording several intraprocedural data elements such as patient age, use of anesthetics, use of paper drapes, experience of the person performing the LP, early stylet removal, and number of attempts. The primary outcome was the ability of the resident to successfully perform an LP. Failure was defined as more than 1,000 red blood cells (RBCs)/mm3, inability of the resident to get cerebrospinal fluid (CSF), or inability to get enough volume for a CSF cell count (ie, adequate volume for a CSF culture but not enough for a cell count).

When analyzing all children age 12 months or younger, the success of LP with early stylet removal was not significant—the final adjusted odds ratio (OR) was 1.9 (95% CI; 0.95–3.9). When evaluating children younger than 12 weeks of age, the OR for successful completion of the procedure using early stylet removal was 2.4 (95% CI; 1.1–5.2), which was significant, suggesting that early stylet removal might be beneficial in LP success in this young group.

A prospective observational study in 2007 by Nigrovic et al evaluated 1,459 pediatric LPs (ages 0 to 22 years) over a 19-month period at a tertiary pediatric emergency department.³ Data collection forms were prospectively obtained and included performer experience, anatomical landmark identification, patient characteristics, local anesthesia, sedation, early stylet removal, and patient movement. The primary outcome was successful LP on first attempt with further analysis by age (3 months or less versus older than 3 months of age). Failure was defined as more than 10,000 RBCs/mm3, the inability to get CSF on the first attempt, or the inability to get enough volume for a CSF cell count (ie, adequate volume for a CSF culture but not enough for a CSF cell count).

The stylet-out LP technique was performed in 29 percent of these first LP attempts. For all children, the stylet-in technique demonstrated an adjusted OR of 1.8 (95% CI; 1.3–2.7) for failure. For kids age 3 months or younger, failure was significantly associated with stylet in, with an OR of 1.4 (95% CI; 1.02–2.0), suggesting that stylet out improves LP success.

Summary: After insertion of the LP needle through the epidermis and subcutaneous tissue with the stylet in, advancing stylet out appears to improve LP success in children.

Dr. Jones

Dr. Cantor is professor of emergency medicine and pediatrics, director of the pediatric emergency department, and medical director of the Central New York Regional Poison Control Center at Upstate Medical University in Syracuse, New York.

References

1. McLennan TA. Removal of the stylet during the performance of lumbar puncture. Can Med Assoc J. 1962;86(12):544.
2. Baxter AL, Fisher RG, Burke BL, et al. Local anesthetic and stylet styles: factors associated with resident lumbar puncture success. Pediatrics. 2006;117(3):876-881.
3. Nigrovic LE, Kuppermann N, Neuman MI. Risk factors for traumatic or unsuccessful lumbar punctures in children. Ann Emerg Med. 2007;49(6):762-771.