Pathophysiologic phenotyping of idiopathic sudden sensorineural hearing loss: toward precision management

Idiopathic sudden sensorineural hearing loss (ISSNHL) is traditionally managed as a uniform clinical emergency using empirical corticosteroid protocols, yet outcomes vary widely, suggesting underlying etiologic heterogeneity. This review aims to propose a precision medicine framework for ISSNHL by re-examining the condition through specific pathophysiologic determinants, including structural third window syndromes, microvascular compromise, and metabolic factors.

A narrative synthesis of emerging evidence regarding 3D-FLAIR MRI, high-resolution CT (HRCT), and metabolic profiling is presented. Illustrative cases of Enlarged Vestibular Aqueduct (EVA) and Superior Semicircular Canal Dehiscence (SSCD) are utilized to highlight the limitations of traditional steroid therapy in structural phenotypes.

A significant proportion of "idiopathic" cases can be stratified into distinct pathophysiologic phenotypes. Structural anomalies (TWS) often exhibit limited steroid responsiveness but benefit from early biomechanical identification. Furthermore, advanced imaging like 3D-FLAIR MRI reveals blood-labyrinth barrier (BLB) disruption as a prognostic marker for vascular-driven hearing loss. Metabolic factors, such as Vitamin D and B12 deficiencies, further modulate cochlear resilience and recovery potential.

SSNHL should be managed as a heterogeneous syndrome. We propose a stratified management algorithm that integrates high-resolution imaging and metabolic screening into early decision-making. Shifting toward pathophysiology-guided care allows for personalized adjuvant strategies (e.g., HBOT, metabolic correction) and more accurate prognostic counseling, ultimately improving individualized patient outcomes.