Histopathological Factors Contributing to Recurrent Meningitis in Inner Ear Malformations.

Abstract

Objective: To analyze histopathological factors contributing to recurrent meningitis in patients with inner ear malformations (IEMs) through examination of two cases from the archives of an otopathology laboratory.

Patients: Two cases with documented IEMs and a history of recurrent meningitis were analyzed from archived human temporal bone specimens in July 2024.

Intervention: Histopathological examination and analysis of temporal bone specimens to identify anatomical defects and infection pathways.

Main outcome measure: Identifying specific anatomical defects and pathways contributing to recurrent meningitis in IEM cases.

Results: Case 1 demonstrated an incomplete partition type I (IP-I) malformation with a stapes footplate fistula, which provided a direct pathway for infection from the middle ear to the inner ear spaces. Case 2 revealed an incomplete partition type III (IP-III) malformation with a deficient otic capsule, presenting multiple potential routes for infection spread due to irregular erosion and minimal bone barrier between middle and inner ear spaces. Both cases resulted in fatal meningitis despite medical intervention.

Conclusions: Recurrent meningitis in IEMs can occur through different pathophysiological mechanisms: either through a discrete stapes footplate fistula or via a deficient otic capsule with multiple potential infection pathways. Management strategies should be tailored to the specific anatomical defect, with surgical intervention focusing on defect repair in stapes footplate fistulas and consideration of subtotal petrosectomy in cases of deficient otic capsule. Vaccination and careful selection of surgical procedures are crucial preventive measures.

Level of evidence: IV.