bubble_chart Overview

Conductive hearing loss caused by direct or indirect trauma that initially exceeds 50dB, or conductive deafness with an air-bone gap greater than 40dB persisting 6 weeks after injury, should also raise suspicion for possible ossicular dislocation or fracture.

bubble_chart Etiology

1. Head trauma

is the main cause of ossicular dislocation and fracture. Approximately 24–30% of head injuries involve various structures within the temporal bone. Among these, incudostapedial joint dislocation is particularly common (accounting for 75% of ossicular injuries); stapedial crus fracture, footplate displacement, and incudomalleolar separation are less frequent (accounting for 25% of ossicular injuries). Occasionally, bilateral sexually transmitted disease changes may occur.

2. Direct injury

to the ossicles: ① Accidental tympanic membrane perforation and ossicular injury during the removal of foreign bodies or cerumen from the external auditory canal; ② Incus dislocation due to overly posterior placement of a ventilation tube for secretory otitis media; prolonged pressure from the tube on the long process of the incus may lead to incus necrosis; ③ Posterior tympanotomy techniques may result in accidental incus dislocation; ④ During mastoid surgery, probing the aditus ad antrum can cause incus dislocation.

bubble_chart Clinical Manifestations

After injury to the tympanic membrane and ossicles, conductive deafness occurs, which may also be accompanied by inner ear injury leading to hearing loss. If it is conductive deafness, the prognosis is generally good, with most cases having the potential for recovery. However, if the conductive deafness exceeds 50dB from the outset, there should be high suspicion of ossicular dislocation or fracture, and the likelihood of natural recovery to normal hearing is very low. Additionally, if conductive deafness with an air-bone gap greater than 40dB persists 6 weeks after the injury, the possibility of ossicular dislocation or fracture should also be considered.

Traumatic conductive hearing loss is mainly caused by hemotympanum, tympanic membrane rupture, ossicular chain dislocation, or fracture. Hemotympanum usually resolves on its own or is discharged through the Eustachian tube within 3 weeks, and hearing may gradually improve. If hemotympanum persists in the epitympanum or if there are residual hematomas in the vestibular or cochlear niches with significant middle ear mucosal edema, hearing recovery may be delayed. In cases of ossicular fracture combined with fracture of the posterosuperior wall of the external auditory canal, adhesion and fixation between the ossicles and the bony tympanic ring may occur, potentially leading to a decline during the hearing recovery process. As for cases complicated by labyrinthine contusion or concussion, the chance of recovery from sensorineural deafness is relatively low.

bubble_chart Treatment Measures

1. Perform tympanotomy and carry out various ossicular chain reconstruction procedures based on the condition of the ossicular injury. Generally, ossicular dislocation often maintains some degree of ossicular movement function due to fibrous bands connecting the ossicles, and hearing usually recovers to a certain extent. Surgical treatment is generally performed 3 months after the injury. However, for early-stage cases or those with vertigo and nystagmus suspected of having stapes inward invasion fracture, surgery should be performed as soon as possible; otherwise, irreversible inner ear lesions may occur, leading to total deafness. Tympanotomy should be performed under antibiotic control of infection. If a stapes fracture is found and has collapsed into the vestibule, the stapes should be lifted or removed and managed as in a stapedectomy. The vestibular perforation should be grafted with vein, fat, or cartilage membrane, and the ossicular chain should be repaired. Finally, the ruptured tympanic membrane should be repaired.

2. Postoperative antibiotics should be administered to prevent infection. For patients with a history of incomplete facial nerve paralysis due to head trauma that later recovered, the risk of recurrent incomplete facial nerve paralysis during middle ear surgery is higher, and caution should be exercised.