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

Area of Science:

• Otology and Neurotology
• Biomedical Engineering
• Computational Mechanics

Background:

• Third-window syndromes (TWS), including superior semicircular canal dehiscence (SSCD) and enlarged vestibular aqueduct (EVA), manifest with paradoxical auditory and vestibular symptoms.
• These symptoms include apparent conductive hearing loss, bone-conduction hyperacusis, and sound- or pressure-induced vertigo.
• Numerical modeling offers a powerful approach to investigate the biomechanical effects of TWS based on lesion characteristics.

Purpose of the Study:

• To systematically review and analyze numerical modeling studies applied to SSCD and EVA.
• To explore how different modeling techniques elucidate the pathophysiology of TWS.
• To assess the potential clinical utility of computational models in understanding and managing TWS.

Main Methods:

• A comprehensive literature search was conducted across PubMed, Scopus, and Google Scholar.
• Nine studies employing lumped-element, finite-element (FE), or computational fluid dynamics (CFD) models for SSCD or EVA were qualitatively analyzed.
• The focus was on how models represent and explain the mechanical consequences of TWS.

Main Results:

• Lumped-element models successfully replicated air-bone gaps and bone-conduction hypersensitivity, demonstrating the influence of lesion size and location.
• FE and CFD simulations provided detailed anatomical insights, linking dehiscence geometry to basilar membrane motion.
• Models explained sound-induced endolymphatic streaming (Tullio phenomenon) and intracranial pressure transmission in EVA, though validation was limited.

Conclusions:

• Numerical models offer valuable, complementary insights into the biomechanics of third-window syndromes.
• Lumped-element models are efficient and clinically relevant, while FE and CFD provide detailed fluid-structure interaction analysis.
• Patient-specific simulations hold future promise for individualized diagnosis and surgical planning in TWS, though currently remain speculative.