From the Guidelines
The C-Reactive Protein (CRP) test in a lumbar puncture (spinal tap) is a valuable diagnostic tool for distinguishing bacterial from viral meningitis in a sick child, with a high negative predictive value, particularly when the Gram stain result is negative 1. When evaluating a sick child with suspected meningitis, a lumbar puncture should be performed to collect cerebrospinal fluid (CSF), and CRP levels should be measured alongside other standard CSF parameters.
- The sensitivity of serum CRP concentration in diagnosing bacterial meningitis ranges from 69% to 99%, and the specificity ranges from 28% to 99% 1.
- The odds ratio (OR) for serum CRP concentration in the diagnosis of bacterial meningitis is 150 (95% CI, 44–509) 1.
- CSF concentrations of CRP have also been evaluated for distinguishing bacterial from viral meningitis, with a sensitivity ranging from 18% to 100%, and a specificity ranging from 75% to 100% 1.
- A normal CRP has a high negative predictive value in the diagnosis of bacterial meningitis, making it a useful tool in patients with CSF findings consistent with meningitis, but for whom the Gram stain result is negative and the physician is considering withholding antimicrobial therapy 1. The decision to perform a spinal tap should be based on the child's clinical presentation, including fever, irritability, lethargy, neck stiffness, or other signs of meningeal irritation.
- CRP levels rise within 4-6 hours of infection onset and peak at 36-48 hours, making it more sensitive than blood cultures in patients who have received prior antibiotic treatment.
- While serum CRP is more commonly measured and also valuable in assessing infection severity, CSF CRP can provide more specific information about central nervous system inflammation.
From the Research
Significance of C-Reactive Protein (CRP) Test in Lumbar Puncture
The CRP test is not explicitly mentioned in the provided studies as a significant component of a lumbar puncture (spinal tap) for a sick child. However, the following points can be inferred about the significance of lumbar puncture in diagnosing central nervous system infections:
- A lumbar puncture is a crucial diagnostic tool for detecting central nervous system infections in infants and children 2.
- The procedure involves inserting a needle into the lower spine to obtain cerebrospinal fluid, which is then sent for testing in a laboratory 2.
- The results of the tests, together with a clinical assessment of a patient, can guide the effective treatment of infections and reduce the risk of neurological conditions 2.
Indications and Contraindications of Lumbar Puncture
The following points highlight the indications and contraindications of lumbar puncture:
- Lumbar puncture is indicated whenever the diagnosis of meningitis is suspected in a child, except in cases of raised intracranial pressure or other contraindications 3, 4.
- The procedure is used to confirm a diagnosis of purulent meningitis, identify the bacteria, and test its sensitivity to antibiotics 3.
- Lumbar puncture can also be used to control cerebrospinal fluid sterilization after therapy and as a prognostic indicator of neurological abnormalities 3.
Role of Lumbar Puncture in Diagnosing Central Nervous System Infections
The following points emphasize the role of lumbar puncture in diagnosing central nervous system infections:
- Lumbar puncture is a valuable diagnostic tool for identifying the causative organism or excluding bacterial meningitis in children with suspected central nervous system infections 5.
- The procedure can contribute to the management of patients by providing crucial information about the infection 5.
- However, the recommendations for undertaking lumbar punctures in children with suspected central nervous system infections are not always followed, and many children who should receive lumbar punctures do not get them 5.