![]() ![]() To account for the masking dilemma in patients with bilateral aural atresia, the sensorineural acuity level (SAL) test should be performed to obtain accurate bone conduction thresholds in each ear. Pure tone and speech audiometry should be performed to obtain air and bone conduction thresholds. The CT allows for the evaluation of the external, middle, and inner ears as well as for the presence of cholesteatoma. The evaluation of the patient with CAA consists of a history, a physical examination, family history, comprehensive audiometry, and HRCT imaging. With recent advances in alternative hearing rehabilitation options such as bone conducting devices, there is an increased interest in preoperative measures that may predict successful hearing outcomes in patients undergoing surgical aural atresia repair. Jahrsdoerfer’s grading system has become widely utilized as a guide for clinicians in determining surgical candidacy. More recent classification systems have focused on high resolution computed tomography (HRCT) imaging findings with the goal of delineating which patients are the best candidates for surgical repair. ![]() ![]() In Group 2 (moderate), there is no EAC and a contracted middle ear, and in group 3 (severe), there is no EAC present, and a severely hypoplastic or absent middle ear space. In Group 1 (mild), there is some part of the external auditory canal (EAC) present. Altmann initially proposed a grading system in 1955 based on the severity of the abnormality. The various classification systems proposed for CAA are based either on a physical exam, imaging, or findings at the time of surgical repair. In some patients, CAA is associated with a craniofacial syndrome such as Treacher-Collins, hemifacial microsomia, or Goldenhar. As a result, inner ear structures are usually not affected in patients with CAA. Conversely, the inner ear primarily derives from the otocyst rather than the branchial apparatus. Likewise, the first and second branchial arches give rise to the axonal hillocks that form the auricle, accounting for the common association between CAA and microtia. Because of the embryologic association between the external ear canal and the first branchial arch, patients with CAA often have a contracted middle ear space and ossicular abnormalities. Arrest of this process prior to canalization at 6 months gestation results in complete atresia, and arrest during canalization results in incomplete atresia or canal stenosis. The primary embryologic abnormality in CAA is failure of the first branchial groove epithelial plate to canalize. The CAA is marked by the absence or stenosis of the external ear canal, and is usually accompanied by the absence of a tympanic membrane, ossicular abnormalities, and microtia. For unknown reasons, CAA occurs more frequently on the right side, and affects males more often than females. Unilateral atresia is far more common than bilateral, on the order of 3–4:1. Predictors of success for atresia surgery will be highlighted as these may be the primary measures by which patients are counseled and ultimately choose treatment.Ĭongenital aural atresia (CAA) occurs in about 1 in 10,000–20,000 live births. In this review, we explore treatment options for patients with UAA, including the use of implantable devices such as bone-anchored hearing devices and implantable middle ear devices. Preoperative tools such as high resolution computed tomography and pure tone and speech audiometry are typically used to provide some insight on the middle ear anatomy and thus predict hearing outcomes following surgical atresia repair. With the advent of new and more widely and easily accessible implantable hearing devices, more options are available for hearing rehabilitation in patients with unilateral or bilateral aural atresia. While the scholastic deficits associated with unilateral sensorineural hearing loss and otitis media with effusion have been well-studied, the disabilities associated with unilateral (or bilateral) aural atresia with its attendant moderate or moderate-severe CHL are less well understood. The absence or stenosis of the ear canal is usually associated with aberrant middle ear morphology and a variable conductive hearing loss (CHL). Unilateral aural atresia (UAA) presents both diagnostic and therapeutic challenges to the clinician. ![]()
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