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Published on: April 9, 2011
Interpretation of Cerebrospinal Fluid White Blood Cell Counts in Young Infants With a Traumatic Lumbar Puncture
Todd W Lyons1, Andrea T Cruz2, Stephen B Freedman3
1Division of Emergency Medicine, Boston Children's Hospital, Boston, MA.
Insights
This study found that correcting cerebrospinal fluid (CSF) white blood cell (WBC) counts in infants with traumatic lumbar punctures reduces pleocytosis diagnoses. However, this correction may lower sensitivity for detecting bacterial meningitis, particularly in younger infants.
Area of Science:
- Pediatrics
- Infectious Diseases
- Clinical Chemistry
Background:
- Traumatic lumbar punctures (LPs) can elevate cerebrospinal fluid (CSF) white blood cell (WBC) counts, complicating the diagnosis of bacterial meningitis in infants.
- Accurate interpretation of CSF WBC counts is crucial for timely and appropriate treatment of suspected meningitis in neonates and young infants.
Purpose of the Study:
- To determine the optimal correction factor for CSF WBC counts in infants experiencing traumatic LPs.
- To evaluate the impact of CSF WBC count correction on the detection of bacterial meningitis and the diagnosis of pleocytosis.
Main Methods:
- Secondary analysis of a retrospective cohort of infants aged ≤60 days with traumatic LPs (CSF RBC count ≥10,000 cells/mm³).
- Defined CSF pleocytosis and bacterial meningitis based on established criteria and CSF culture results.
- Utilized linear regression to derive a CSF WBC correction factor and compared corrected vs. uncorrected counts for diagnostic accuracy.
Main Results:
- A CSF RBCs:WBCs ratio of 877:1 was derived.
- Corrected CSF WBC counts showed lower sensitivity for bacterial meningitis (67%) compared to uncorrected counts (88%).
- Correction significantly reduced the identification of CSF pleocytosis (33% corrected vs. 78% uncorrected) and misclassified 7 additional infants with bacterial meningitis.
Conclusions:
- Correcting CSF WBC counts in infants with traumatic LPs substantially decreases the diagnosis of pleocytosis.
- The correction factor misclassified only one infant with bacterial meningitis aged 29-60 days, suggesting a potential trade-off between reducing false positives and sensitivity.
Study Objective:
We determine the optimal correction factor for cerebrospinal fluid WBC counts in infants with traumatic lumbar punctures.
Methods:
We performed a secondary analysis of a retrospective cohort of infants aged 60 days or younger and with a traumatic lumbar puncture (cerebrospinal fluid RBC count ≥10,000 cells/mm3) at 20 participating centers. Cerebrospinal fluid pleocytosis was defined as a cerebrospinal fluid WBC count greater than or equal to 20 cells/mm3 for infants aged 28 days or younger and greater than or equal to 10 cells/mm3 for infants aged 29 to 60 days; bacterial meningitis was defined as growth of pathogenic bacteria from cerebrospinal fluid culture. Using linear regression, we derived a cerebrospinal fluid WBC correction factor and compared the uncorrected with the corrected cerebrospinal fluid WBC count for the detection of bacterial meningitis.
Results:
Of the eligible 20,319 lumbar punctures, 2,880 (14%) were traumatic, and 33 of these patients (1.1%) had bacterial meningitis. The derived cerebrospinal fluid RBCs:WBCs ratio was 877:1 (95% confidence interval [CI] 805 to 961:1). Compared with the uncorrected cerebrospinal fluid WBC count, the corrected one had lower sensitivity for bacterial meningitis (88% uncorrected versus 67% corrected; difference 21%; 95% CI 10% to 37%) but resulted in fewer infants with cerebrospinal fluid pleocytosis (78% uncorrected versus 33% corrected; difference 45%; 95% CI 43% to 47%). Cerebrospinal fluid WBC count correction resulted in the misclassification of 7 additional infants with bacterial meningitis, who were misclassified as not having cerebrospinal fluid pleocytosis; only 1 of these infants was older than 28 days.
Conclusion:
Correction of the cerebrospinal fluid WBC count substantially reduced the number of infants with cerebrospinal fluid pleocytosis while misclassifying only 1 infant with bacterial meningitis of those aged 29 to 60 days.
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