#Auditory canal skin

Mobilizing incus from atretic plate may risk ossicle chain injury and labyrinthine trauma transmitted through stapes. Coronal high-resolution CT scan through right tympanic cavity shows contact of long incus process to atresia plate ( arrow) in slightly reduced middle ear space. Patient underwent surgery on left side 1 yr earlier, at age 16. 17-year-old girl with bilateral external auditory canal atresia. A tympanic cavity width less than 3 mm from the promontory to the atretic plate in the coronal plane is considered inadequate for reconstruction (Figs. Reduced middle ear space was correlated with unfavorable outcome of surgery. 5B ) is indispensable for successful surgery. Middle ear cavity.-Aerated tympanic cavity with preserved function of the tuba auditiva ( Fig. Because patient experiences unilateral atresia, operative reconstruction is not recommended. Stylomastoid foramen ( white arrowhead) is displaced in anterolateral direction. Slight caudal rotation of posterior stapes crus ( small white arrow) due to close relationship between facial nerve and stapes can be seen. Large white arrow points to inferiorly displaced tympanic facial nerve segment overlying oval window. Coronal high-resolution CT scan obtained through middle ear shows oval window ( black arrow) and round window ( black arrowhead) with normal diameters. 7-year-old boy with unilateral left-sided external auditory canal atresia. Patients with more than 5 points on the grading system are considered candidates for surgical reconstruction.įig. A point is assigned for a fairly developed auricle. The final item consists in the clinical aspect of the external ear, which is added to the CT criteria. One point is given for each item with correct or only slightly dysplastic appearance, with the exception of the stapes, which receives 2 points when presented.

The criteria include assessment of the stapes, oval window and round window, middle ear space, mastoid pneumatization, facial nerve course, malleus–incus complex, and incus–stapes connection. Using nine reproducible criteria, one calculates a score to predict postoperative improvement of the speech reception threshold. Yeakley and Jahrsdoerfer described a 10-point rating scale for the selection of surgical candidates by comparing high-resolution CT findings to postsurgical hearing results. Unlike unilateral atresia, in which normal speech development is ensured, bilateral atresia requires early amplification with a bone conduction hearing aid and surgery on the more suitable ear in childhood. Īlthough sensorineural hearing is usually maintained in patients without a major congenital syndrome, audiometric evaluation is indispensable to ensure that sufficient sensorineural hearing is present.

#Auditory canal skin

The newly generated canal is then covered with a skin graft. The temporalis fascia is grafted as a new tympanic membrane to the ossicles or to a stapes prosthesis. Both transmastoid and anterior approaches are followed by mobilization of the ossicles attached to the atretic bone (usually the hammer neck). Drilling is started posterior to the glenoid fossa and anterior to the mastoid cells and is continued in the direction of the middle cranial fossa to reach the epitympanum below the tegmen to avoid ossicle or facial nerve injury. For the anterior approach, opening the mastoid cells is avoided by creating a cylindric canal through the atretic plate. The drawback of this approach is a large mastoid defect, causing an increased risk of local infection problems. After the transmastoid approach has been performed, the mastoid air cells are first removed, providing middle ear visualization during the subsequent dissection of the atretic plate. Both techniques are initiated with a postauricular incision and elevation of the auricle. Two surgical techniques have been established, the transmastoid and the anterior approaches.