mr of th e normal and abnormal internal auditory canal

#Mr of th e normal and abnormal internal auditory canal series#

The positions and relationships of the ossicles in the middle ear were evaluated. Fixation was defined as the presence of an osseous bar between the ossicles and the margins of the middle ear cavity or when the ossicles were not separable from the walls of the middle ear cavity. 10, 11 The presence of ossicular anomalies, including fixation, abnormal position, and abnormal shape or size, was noted. HRCT of the temporal bone was evaluated for findings based on the criteria developed by Jahrsdoerfer et al 9 for identifying suitable candidates with congenital aural atresia for surgery. HRCT studies were reviewed by a pediatric neuroradiologist with 17 years of experience and a pediatric neuroradiology fellow. Audiograms were reviewed for the severity of conductive hearing loss, and the pure tone average was graded as mild (20–40 dB), moderate (40–60 dB), or severe/profound (≥60 dB). The electronic medical records were reviewed for the presence or absence of an abnormal pinna. Grade I microtia is characterized by a hypoplastic auricle with all the identifiable landmarks, grade II microtia consists of an abnormal auricle without some identifiable landmarks, grade III microtia is recognized by a very small auricular tag, and anotia is classified as grade IV. Children with syndromes associated with temporal bone abnormalities were excluded.

The inclusion criteria were patients with unilateral congenital EAC stenosis of <50% diameter on CT, a normal pinna or grade I microtia, and a diagnostic temporal bone HRCT. A PACS search was performed with the Boolean function combining “external canal,” “external auditory canal” AND “stenosis,” or “stenotic” for identifying relevant cases of CT of the temporal bones performed during a 5-year period (2009–2013).

#Mr of th e normal and abnormal internal auditory canal series#

This was a Health Insurance Portability and Accountability Act–compliant retrospective case series performed after approval from the institutional review board at a tertiary referral center. We describe the clinical presentation and audiometric and HRCT findings in a group of patients with unilateral CHL and a normal or minimally abnormal pinna associated with mild stenosis of the EAC. High-resolution CT (HRCT) is beneficial in elucidating the etiology of congenital CHL and guides surgical management in these patients. 5 The absence or subtle nature of external ear anomalies in this patient population could potentially lead to delay in identification of the etiology of hearing loss. External auditory canal stenosis or atresia in the absence of anomalies of the pinna is uncommon but has been described in nonsyndromic children and children with chromosome 18q deletion. 4 Ossicular anomalies such as absence, fixation, and abnormal fusion have been described in children with or without EAC stenosis or atresia. These patients present with conductive hearing loss related to stenosis or atresia of the external auditory canal (EAC). 3 More commonly, anomalies of the middle ear are linked to congenital anomalies of the pinna, which has an incidence of approximately 1 in 11,000 children. 2 Congenital conductive hearing loss (CHL) may be related to an isolated anomaly of the middle ear without associated anomalies of the external ear or canal. 1 Hearing loss can be due to central auditory dysfunction, conductive, sensorineural, or a combination. ABBREVIATIONS: CHL conductive hearing loss EAC external auditory canal HRCT high-resolution CTĬongenital hearing loss affects 1– children.