What is the approach to suspected meningitis with a normal physical examination?

Approach to Suspected Meningitis with Normal Physical Examination

Even with a normal physical examination, lumbar puncture is strongly recommended in patients with suspected bacterial meningitis, as no clinical sign is present in all patients with meningitis. 1

Initial Assessment

• Patients with suspected meningitis require immediate evaluation despite normal examination findings, as the absence of classic symptoms does not rule out meningitis 1
• Blood cultures should be obtained within the first hour of arrival at hospital, before antibiotic administration 1, 2
• Document Glasgow Coma Scale (GCS) score to assess severity and monitor changes 1, 2

Diagnostic Approach

Lumbar Puncture (LP)

• LP should be performed within 1 hour of hospital arrival if no contraindications exist 1, 2
• CSF analysis remains the principal contributor to final diagnosis with an area under the curve of 0.95 in receiver operating characteristics analysis 1
• CSF white blood cell count is the best diagnostic parameter for differentiating bacterial meningitis from other diagnoses 1

Contraindications to Immediate LP

• Focal neurological signs 1
• Presence of papilledema 1
• Continuous or uncontrolled seizures 1
• GCS ≤ 12 1
• New-onset seizures 1
• Severe immunocompromised state 1

Neuroimaging Before LP

• Consider cranial imaging before LP in patients with:
  • Severely altered mental status (GCS < 10) 1
  • Focal neurologic deficits 1
  • New-onset seizures 1
  • Severe immunocompromised state 1
• Note: Cranial imaging before LP has been identified as an important cause of delay in antibiotic treatment 1

Treatment Approach

• Antibiotics should be administered within 1 hour of arrival, regardless of whether LP has been performed 1
• If LP is delayed due to neuroimaging or other reasons, antibiotics should be given immediately after blood cultures are taken 1, 2
• For adults without risk factors for Listeria monocytogenes, a third-generation cephalosporin (ceftriaxone or cefotaxime) is recommended 1, 3
• Standard dosing for ceftriaxone in adults with meningitis is 2g IV twice daily 3

Special Considerations

• Patients with predominantly sepsis or rapidly evolving rash should receive immediate antibiotics after blood cultures and fluid resuscitation, with LP deferred 1
• Even with normal examination, respiratory isolation is recommended until meningococcal meningitis is excluded or the patient has received 24 hours of appropriate antibiotics 1
• All patients should be assessed for potential long-term sequelae before discharge, including hearing tests if clinically indicated 1

Common Pitfalls to Avoid

• Delaying antibiotics while waiting for LP or neuroimaging increases mortality 2
• Relying solely on classic meningeal signs (Kernig sign, Brudzinski sign) which have variable sensitivity and specificity 4, 5
• Failing to recognize that normal physical examination does not exclude meningitis 1
• Underestimating the importance of CSF examination in patients with suspected meningitis despite normal examination 1

Algorithm for Management

1. Assess for signs of shock, sepsis, or rapidly evolving rash

   • If present: Immediate antibiotics after blood cultures, fluid resuscitation, defer LP 1
   • If absent: Proceed to step 2

2. Evaluate for contraindications to immediate LP

   • If contraindications present: Obtain blood cultures, start antibiotics, arrange neuroimaging, perform LP when safe 1, 2
   • If no contraindications: Perform LP within 1 hour, start antibiotics immediately after LP 1, 2

3. Interpret CSF results

   • Increased CSF white blood cells: Diagnosis of meningitis confirmed 1
   • Normal CSF: Consider alternative diagnoses but maintain high index of suspicion if clinical picture suggests meningitis 5, 6

4. Continue appropriate antimicrobial therapy based on CSF results and local resistance patterns 1, 3