What are indications and contraindications for lumbar puncture in the workup of Haemophilus influenzae type b (Hib) meningitis?

Updated: Jul 09, 2018
  • Author: Prateek Lohia, MD, MHA; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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Answer

Lumbar puncture should be performed unless some specific contraindication exists. In young febrile children, lumbar puncture should be performed if meningitis cannot be otherwise excluded (after appropriate consideration of such contraindications as asymmetrical space-occupying lesion).

Lumbar puncture should also be strongly considered if another definite source of infection and fever cannot be found and outpatient antibiotic therapy is to be provided. In such cases, performing puncture avoids the diagnostic difficulties associated with partially treated meningitis in the event that the infant returns within the next few days with clinical worsening.

Care must be taken not to perform lumbar punctures in patients who are at risk for brain herniation or are manifesting signs of impending herniation. Although the scientific underpinnings of allegations that there is a relationship between lumbar puncture and herniation are in many cases weak, they may not appear to be so in the minds of nonmedical personnel called upon to review such an alleged relationship in retrospect in a courtroom.

Findings that may indicate the onset of herniation or impending herniation include focal brainstem signs, especially if present unilaterally (eg, dilation of a pupil, diminution or loss of pupillary reactivity, diminution or loss of abducens function); head tilt; meningismus; deterioration in mental status; visual field defect; focal seizures; vomiting; increased tone in the lower extremities; Cushing reflex (ie, elevated blood pressure with slow heart rate); and hyperventilation or other disturbances of breathing rhythm consistent with brainstem regulatory failure.

Papilledema is a very important sign, but it may not develop until after several hours of increased intracranial pressure (ICP), and a large segment of the medical community cannot reliably determine the pertinent early funduscopic changes. Venous pulsation presence may be reassuring, but the absence of pulsations is of greatest value only in cases where they were known to be present prior to the current urgent presentation.

In cases where concern is raised by any of these signs, deferring lumbar puncture until after brain imaging can be obtained is appropriate. However, in all such cases wherein the diagnosis of meningitis is entertained, obtaining a blood culture and initiating appropriate broad-spectrum antibiotic therapy immediately afterward is crucial, so that performance of the brain scan does not delay initiation of treatment.

The authors re-emphasize the point that the performance of brain imaging studies should never delay the initiation of treatment for increased intracranial pressure or seizures. Note that even in cases where intravenous (IV) antibiotics have been administered immediately before a computed tomography (CT) scan, CSF from a lumbar puncture performed after the completion of the scan seldom has been sterilized by the antibiotics.

In the absence of focal neurologic findings (such as those noted above), the risk of herniation in cases of Hib meningitis is low, and one can safely proceed to lumbar puncture without imaging. In general, evidence of raised ICP is not considered a categorical contraindication to lumbar puncture, as long as no signs suggesting focal space-occupying lesions are found. If evidence exists for increased ICP, a small needle (#22 gauge) should be employed by the most skilled available person, and only as much CSF as is needed for essential tests should be collected.


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