Mechanistic insights into third-window syndromes through numerical modeling: A PRISMA scoping review

Abstract

Introduction: Third-window syndromes (TWS), including superior semicircular canal dehiscence (SSCD) and enlarged vestibular aqueduct (EVA), cause paradoxical auditory and vestibular symptoms such as apparent conductive loss, bone-conduction hyperacusis, and sound- or pressure-induced vertigo. Numerical modeling provides a unique means to explore the mechanical consequences of lesion size, geometry, and location.

Methods: A structured search of PubMed, Scopus, and Google Scholar (July 2025) identified nine studies applying lumped-element, finite-element (FE), or computational fluid dynamics (CFD) models to SSCD or EVA, which were analyzed qualitatively.

Results: Lumped-element models reproduced air–bone gaps and bone-conduction hypersensitivity, showing that lesion size and location modulate functional severity. FE and CFD simulations offered anatomically detailed insights, revealing that dehiscence geometry strongly shapes basilar membrane motion, that sound-induced endolymphatic streaming can account for the Tullio phenomenon, and that large vestibular aqueducts transmit intracranial pressure fluctuations. Validation across studies remained limited.

Conclusion: Numerical models provide complementary insights into TWS. Lumped-element approaches are rapid and clinically interpretable, while FE and CFD enable detailed exploration of fluid–structure interactions. Patient-specific simulations may eventually support individualized diagnosis and surgical planning but remain speculative.