Objective To investigate the mechanism of hearing loss caused by tympanic membrane(TM)per-foration.Methods We constructed a full ear finite element model,and the personalized finite element model of TM perforation was constructed to simulate hearing loss caused by TM perforation.The difference between the displace-ment response of the basement membrane and the baseline was applied to simulate hearing loss,and the contribution of various components of the middle ear to hearing loss was analyzed to study the mechanism of hearing loss caused by TM perforation.Results If the coupling of the round window membrane and the middle ear air was removed,the hearing loss at the low frequency was about 40 dB,while the high-frequency was the same as the baseline.Re-moval of the coupling between the inner side of the eardrum and the middle ear cavity resulted in a reduction in par-tial low-frequency hearing and an increase in high-frequency hearing loss.The continuous disconnection between the air in the external auditory canal and the air in the middle ear cavity increased the low-frequency hearing loss.How-ever,after the removal of the coupling between the round window membrane and the middle ear air and the connec-tion between the middle ear air and the lateral side of the TM,the original hearing loss of 40 dB at low-frequency dropped to 10 dB.While the removal of the coupling between the middle ear cavity air and the ossicular chain had no significant impact on hearing loss.Conclusion TM perforation may cause hearing loss by both the reduction of sound transmission and the reduction of sound pressure difference between the two sides of TM.The round window membrane can counteract the influence of the hearing loss caused by TM perforation.

Objective To analyze the characteristics of nystagmus during the Dix-Hallpike and Roll tests in patients with benign paroxysmal positional vertigo (BPPV) using three-dimensional videonystagmography (3D-VNG), in order to to optimize diagnostic and therapeutic strategies of BPPV. Methods A retrospective analysis was conducted on 68 patients with posterior semicircular canal (PSC)-BPPV and 26 patients with horizontal semicircular canal (HSC)-BPPV. Nystagmus data obtained from 3D-VNG were reviewed for all patients, with a focus on the eye movement components during the Dix-Hallpike test in PSC-BPPV patients and the Roll test in HSC-BPPV patients. The direction and reversal rates of the vertical, horizontal, and torsional components were recorded and analyzed. Results All PSC-BPPV patients exhibited highly consistent three-dimensional nystagmus characteristics during the Dix-Hallpike test: vertical nystagmus was uniformly upward, torsional nystagmus was predominantly clockwise in left-side BPPV patients (17/23) and counterclockwise in right-side BPPV patients (44/45), while the horizontal component was mostly directed contralaterally (50/68); upon transitioning from the head-hanging to the sit-up position, vertical nystagmus components in all patients reversed, and torsional and horizontal nystagmus components reversed in approximately 50.0% or more patients. Among HSC-BPPV patients, right-side BPPV patients all showed right-beating (geotropic) horizontal nystagmus with predominantly upward vertical component (16/19), while most left-side BPPV patients showed left-beating horizontal nystagmus (6/7) with predominantly downward vertical component (6/7). During head rotation toward the healthy side, most (25/26) HSC-BPPV patients exhibited a reversal in the horizontal nystagmus direction, reduced intensity compared to the affected side, with a reversal in vertical components in 3 patients, and atypical torsional components. Conclusions 3D-VNG could precisely quantitative analyze three-dimensional features of nystagmus in BPPV patients, improve diagnostic accuracy in canal and side localization, particularly in PSC-BPPV patients.