Biomechanical Mechanisms of Vocal Fold Nodule and Polyp Formation: A Review.

Vocal fold (VF) nodules and polyps are the most common benign laryngeal lesions encountered in clinical practice, particularly among professional voice users. Although both lesion types are routinely attributed to phonotrauma, the diverging clinical behavior of nodules and polyps, bilateral fibrotic lesions responsive to voice therapy versus unilateral edematous or hemorrhagic lesions frequently requiring surgical excision, has not been adequately explained by behavioral correlates alone. This review reorganizes the biomechanical evidence around the two lesions as distinct pathogenic entities. Nodule pathogenesis is framed as the cumulative tissue response to chronic, symmetric, repetitive phonotrauma, driven principally by the nonlinear stiffening of the vocal ligament and by collision force concentration at the mid-membranous VF. Polyp pathogenesis is framed as the acute consequence of high-magnitude stress transients, often involving chaotic vocal-ventricular fold interactions that exceed the vascular rupture threshold of the lamina propria microvasculature, producing capillary disruption, fluid extravasation, and edema within Reinke's space. Fluid accumulation studies, capillary pressure modeling, and hydration research are integrated into the polyp framework to explain the gelatinous and hemorrhagic morphology that distinguishes polyps from nodules. Vibratory asymmetry and turbulent airflow are presented as amplifying factors that lower the threshold for both lesion types and perpetuate them once formed. The review concludes with clinical implications for prevention, diagnosis, and the rational selection of behavioral versus surgical intervention.