Is a lumbar puncture (LP) indicated in this patient?

Lumbar Puncture Indications and Contraindications

Lumbar puncture (LP) should NOT be performed if the patient has clinical contraindications indicating possible raised intracranial pressure, coagulopathy, local skin infection at the puncture site, or clinical instability. 1

Clinical Assessment for LP Safety

Clinical assessment, rather than CT imaging alone, should be the primary determinant of whether it is safe to perform a lumbar puncture. The following contraindications should be carefully evaluated:

Absolute Contraindications

• Signs of increased intracranial pressure:
  • Moderate to severe impairment of consciousness (GCS <13)
  • New onset seizures
  • Focal neurological signs
  • Papilledema
  • Abnormal posture or posturing 1
• Coagulopathy:
  • Current anticoagulation therapy (unless appropriately reversed)
  • Platelet count <100 × 10⁹/L
  • Rapidly falling platelet count 2, 1
• Local skin infection at puncture site 2
• Clinical suspicion of spinal cord compression 2
• Clinically unstable patient 2

Imaging Considerations

• If clinical contraindications to immediate LP exist, a CT scan should be performed as soon as possible 2
• LP should be reconsidered on a case-by-case basis after imaging, unless:
  • Imaging reveals significant brain shift
  • Tight basal cisterns are identified
  • An alternative diagnosis is established
  • The patient's clinical condition changes 2, 1

Special Considerations

Thrombocytopenia

• Traditional guidelines recommend platelet counts ≥100 × 10⁹/L for LP 2, 1
• Recent research suggests that lower thresholds may be safe in certain circumstances:
  • A 2023 study found no significant difference in bleeding complications between patients with platelet counts above or below 50 × 10⁹/L, though higher rates of traumatic taps were observed in patients with counts <50 × 10⁹/L 3
  • Another 2023 study showed the incidence of post-LP spinal bleeding was not significantly associated with platelet counts below 50,000/μL 4

Anticoagulation

• For anticoagulated patients:
  • Adequate reversal with protamine for those on heparin
  • Vitamin K, prothrombin complex concentrate, or fresh frozen plasma for those on warfarin 2
• Consult hematology if unclear how to proceed 2

Suspected CNS Infection

• If bacterial meningitis is suspected and LP is delayed or contraindicated:
  • Obtain blood cultures immediately
  • Start appropriate empirical antibiotic therapy before imaging studies
  • Never delay antimicrobial therapy while awaiting CSF collection 1

Follow-up Considerations

• If an initial LP is non-diagnostic, consider a second LP 24-48 hours later 2
• In viral encephalitis, approximately 5-10% of adults with proven HSV encephalitis may have normal initial CSF findings with no pleocytosis and a negative HSV PCR 2
• If an LP is not possible initially, the situation should be reviewed every 24 hours, and an LP performed when it is safe to do so 2

Safety Improvements

• Implementation of an LP safety checklist can improve safety and efficiency by ensuring availability of key clinical information and test results prior to the procedure 5
• Use of atraumatic needle tips can reduce complications such as post-dural puncture headache 1, 6

In summary, while LP is an essential diagnostic procedure for suspected CNS infections and other neurological conditions, patient safety must be prioritized by carefully assessing for contraindications before proceeding.