#AURAL ATRESIA PATCH#

Due to different embryological development of the External EarĮxternal ear includes the auricle (Fig 2A) and external auditory canal (EAC).

#AURAL ATRESIA PATCH#

Otic placode is a thickened ectodermal patch situated adjacent to the hind brain and above the branchial arches. The first and the second branchial arches give rise to the external and middle ear structures while the inner ear develops from the otic placode. The mesenchymal tissue (mesoderm) in the head and neck region of the embryo forms the branchial arches separated by clefts on the ectodermal surface and pouches on the endodermal surface. The surgical corridors discussed in the aMEI score is beyond the scope of this article. This pictorial review intends to acquaint the readers regarding the major external, middle ear and mastoid anomalies mentioned in these scoring systems after briefly reviewing the embryology and normal anatomy of external and middle ear. A new scoring system- Active Middle Ear Implant Score (aMEI score) has been developed to predict risk stratification and decision making in implantation (Table 3) which excludes external ear and malleus/incus anomalies 6 The two most commonly used scoring systems developed to predict the post-operative hearing outcome in these patients are Jahrsdoerfer 4 (Table 1) and modified grading system 5 (Table 2). Audiological testing and HRCT temporal bone are recommended to assess whether the patient is a surgical candidate for canaloplasty and tympanoplasty. For bilateral atresia patients, a long-term bone conducting hearing device is another option till they are taken up for surgical correction. Middle ear implants hold promise as they bypass the malformed ossicles and external auditory canal and are directly coupled to the stapes (most favourable option), the remnant chain or round window membrane. 3 It suggests that patients with both bilateral and unilateral atresia should be provided with conductive hearing device (headband) as soon as possible to be later replaced by bone-conduction or an active middle ear implant. Lubeck flowchart has been recently proposed for management of patients with aural atresia. There are mainly three surgical management strategies for CAA which include reconstructive surgery (canaloplasty combined with tympanoplasty), active middle ear implantation and passive or active bone conduction implantation. Since inner ear is unaffected in most of the cases, hearing impairment is most often the conductive type. The principal clinical complaints in CAA are hearing impairment and cosmetic concerns. 1 Although it most often occurs sporadically, it can occasionally be a part of syndromes like Goldenhar syndrome, Treacher Collin syndrome, Crouzon syndrome and Pierre Robin syndrome. It is more commonly unilateral than bilateral and is more frequent in males. It is a rare anomaly which occurs in 1 in 10,000 to 20,000 live births. This pictorial review aims to review the spectrum of anomalies involving critical structures in CAA on HRCT along with their clinical significance.Ĭongenital aural atresia (CAA) is a congenital anomaly which encompasses in its scope, malformations of external auditory canal (EAC), auricle, middle ear and seldom inner ear. High resolution computed tomography (HRCT) is the optimal investigation which provides required anatomical information and plays a pivotal role in deciding the management strategy. Surgical management if planned, depends on the extent of associated temporal bone anomalies and hence necessitates comprehensive knowledge about the normal and abnormal anatomy of these structures. The management in such patients is variable and consists of rehabilitative hearing aids or surgical correction depending on various patient factors like associated temporal bone abnormalities, degree of hearing impairment and laterality. It also embodies a spectrum of temporal bone abnormalities including anomalies of middle ear, ossicles, facial nerve, oval window, round window, mastoid pneumatization, temporomandibular joint and occasionally inner ear and vascular anomalies. Congenital aural atresia (CAA) is characterized by hypoplasia or aplasia of external auditory canal associated with auricular deformity.

Aural atresia