From the Guidelines
Lumbar puncture in infants is indicated primarily for diagnosing meningitis, encephalitis, and subarachnoid hemorrhage, and should be performed when an infant presents with fever without source, irritability, lethargy, bulging fontanelle, nuchal rigidity, seizures, or altered mental status, especially in those under 2 months. The decision to perform a lumbar puncture is guided by clinical assessment rather than CT scanning, and should be considered in infants with suspected CNS infection, particularly if they are under 18 months old, as stated in the guidelines for the management of convulsions with fever 1.
Indications for Lumbar Puncture
- Fever without source, especially in infants under 2 months
- Irritability, lethargy, bulging fontanelle, nuchal rigidity, seizures, or altered mental status
- Evaluating for increased intracranial pressure
- Administering intrathecal medications
- Diagnosing certain neurological conditions like Guillain-Barré syndrome
Contraindications for Lumbar Puncture
- Skin infection at the puncture site
- Signs of increased intracranial pressure with risk of herniation
- Uncorrected bleeding disorders
Pre-Procedural Considerations
Before performing a lumbar puncture, clinicians should stabilize the infant, obtain informed consent, and consider appropriate analgesia such as EMLA cream or lidocaine infiltration, as suggested by the clinical policy for well-appearing infants and children younger than 2 years of age presenting to the emergency department with fever 1. The CSF obtained should be sent for cell count, glucose, protein, culture, and sometimes PCR testing for viral pathogens.
Importance in Neonates and Young Infants
In neonates and young infants, lumbar puncture is particularly important as they may not display classic signs of meningitis, making clinical diagnosis challenging without CSF analysis, and the performance of a lumbar puncture may still be considered in full-term well-appearing febrile infants aged 29 to 90 days, as stated in the clinical policy for well-appearing infants and children younger than 2 years of age presenting to the emergency department with fever 1. However, the most recent and highest quality study on this topic is from 2016, which provides the most up-to-date guidance on the management of febrile infants 1.
From the Research
Indications for Lumbar Puncture in Infants
The following are indications to perform a lumbar puncture on an infant:
- Suspected central nervous system infection, such as meningitis 2, 3
- Suspected subarachnoid hemorrhage 3
- Evaluation of possible demyelinating syndromes, such as multiple sclerosis 4
- Diagnosis and management of pseudotumor cerebri 4
- Evaluation of spontaneous intracranial hypotension, idiopathic intracranial hypertension, Guillain-Barré syndrome, and malignancy 3
- Diagnosis of leptomeningeal carcinomatosis, which can mimic central nervous system infection 3
Clinical Considerations
Lumbar puncture is a crucial diagnostic tool in infants, and its performance should be guided by a thorough understanding of the underlying medical conditions and the potential risks and benefits of the procedure 4, 2, 5. The decision to perform a lumbar puncture should be based on a careful evaluation of the clinical presentation and the potential diagnostic yield of the procedure 2, 3.
Diagnostic Yield
The diagnostic yield of lumbar puncture in infants can be high, particularly in cases of suspected central nervous system infection or subarachnoid hemorrhage 2, 3. The analysis of cerebrospinal fluid can provide valuable information on the diagnosis and management of these conditions, and can help guide treatment decisions 4, 3.