A 6-year-old child with bacterial meningitis (CSF: WBC 2000/mm³, 92% neutrophils, protein 220 mg/dL, glucose 18 mg/dL vs blood 90 mg/dL) has been started on IV ceftriaxone. Dexamethasone is given as adjunctive therapy. The primary mechanism by which dexamethasone reduces meningitis-associated hearing loss is:
- A Reducing bacterial replication in the CSF by enhancing antibiotic penetration
- B Suppressing cytokine-mediated cochlear inflammation and endolymphatic labyrinthitis ✓
- C Preventing cerebral edema and reducing intracranial pressure
- D Inhibiting matrix metalloproteinases causing BBB breakdown
Explanation
Dexamethasone reduces hearing loss in bacterial meningitis primarily by suppressing the intense cytokine and inflammatory mediator cascade (TNF-alpha, IL-1, prostaglandins) in the subarachnoid space and cochlea. This inflammatory cascade, triggered by bacterial lysis products (LPS, cell wall fragments), causes labyrinthitis and cochlear damage. Evidence from randomized trials (particularly Hib meningitis) shows that dexamethasone reduces hearing loss by ~50% when given before or with the first antibiotic dose. Dexamethasone does not enhance antibiotic penetration or kill bacteria. Cerebral edema reduction is a secondary benefit.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.