What is the treatment for suspected meningitis?

Pupillary Examination in Suspected Meningitis

Immediate Clinical Assessment

Pupillary examination is a critical component of the initial neurological assessment in suspected meningitis, as abnormal pupils (unequal, dilated, or poorly reactive) indicate increased intracranial pressure or brainstem herniation and represent an absolute contraindication to lumbar puncture until neuroimaging excludes brain shift. 1, 2

Key Pupillary Findings and Their Significance

• Fixed, dilated, or asymmetric pupils suggest impending or ongoing cerebral herniation and mandate immediate neuroimaging before any consideration of lumbar puncture 1, 2

• Pupillary abnormalities fall under the broader category of "focal neurological signs" which are explicit contraindications to immediate LP in the UK Joint Specialist Societies guidelines 1

• These findings should trigger urgent CT head imaging to assess for mass effect, significant brain swelling, or midline shift that would predispose to cerebral herniation post-LP 1

Integration into Initial Management Algorithm

Within the First Hour of Arrival

• Document Glasgow Coma Scale score immediately - this includes pupillary response as part of the neurological assessment 1, 2

• Obtain blood cultures within 1 hour before antibiotic administration 1, 2

• Assess for LP contraindications, which include: 1, 2

  • Focal neurological signs (including abnormal pupils)
  • Papilledema (though inability to visualize the fundus is NOT a contraindication)
  • Continuous or uncontrolled seizures
  • GCS ≤ 12
  • Respiratory or cardiac compromise

If Pupils Are Normal and No Other Contraindications Exist

• Perform LP within 1 hour of hospital arrival 1, 2

• Administer antibiotics immediately after LP and within the first hour 1, 2

• For adults, empiric therapy is ceftriaxone 2g IV twice daily (or cefotaxime) plus vancomycin in regions with potential pneumococcal resistance 3, 4

If Pupils Are Abnormal or Other Contraindications Present

• Start antibiotics immediately after blood cultures - do NOT wait for LP or neuroimaging 1, 2, 5

• Obtain urgent CT head to assess for contraindications to LP 1, 2

• Perform LP only after imaging clears the patient (no mass effect, no significant brain swelling), ideally within 4 hours of starting antibiotics to maximize culture yield 1, 2

Critical Pitfalls to Avoid

• Never delay antibiotics while waiting for LP or neuroimaging - delays increase mortality significantly 2, 6, 7

• Never perform LP in a patient with abnormal pupils without prior neuroimaging - this risks fatal cerebral herniation 1, 2, 5

• Do not assume normal pupils mean low risk - patients with meningitis can deteriorate rapidly even with initially reassuring findings 5

Adjunctive Therapy

• Dexamethasone should be administered before or with the first antibiotic dose to reduce neurological complications in pneumococcal meningitis 5, 8

• Consider immediate ICU transfer for patients with abnormal pupils, as this indicates severe disease requiring continuous monitoring 5