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Congenital stapes and oval window dysplasia: a case report
Content Congenital middle ear anomalies arе a rare cause of conductive hearing loss. They occur with concomitant external ear defects or as an isolated entity. Diagnosis may be made via high-resolution computed tomography, but details appear during exploratory tympanotomy.
A 15-year-old female patient reported unilateral tinnitus and non-progressing hearing impairment without concomitant otologic symptoms. The patient did not notice the onset but rather realised a preexisting difference in hearing on both sides. Physical exam and otoscopy were uneventful. Pure tone audiometry proved a left-sided conductive hearing loss with a mean of 65dB and air-bone gap 45dB. High-resolution CT did not depict abnormalities of the middle and inner ear structures. An ossicular disorder was pondered and an exploratory tympanotomy was attempted.
Intraoperatively stapes and oval window dysplasia were found. The stapes head and the stapedius muscle were present, the crura were missing, the anatomical landmarks of both oval and round windows were unclear, facial canal dehiscence was noted. Cochleostomy at the presumed normal location of the oval window was created. At this point, some movement beyond the promontory was observed at the expected site of the round window. A K-Piston prosthesis was placed. The postoperative course was uneventful, apart of a late transient facial palsy which resolved under conservative treatment. Six weeks postoperatively pure tone audiometry showed bone conduction improvement of 35dB and air-bone gap closure of 25dB.
Our case overlays with the majority of the published data on congenital middle ear anomalies. CT findings were negative. Only exploratory tympanotomy demonstrated the anatomic anomaly. Hearing improvement was achieved via cochleostomy and stapedoplasty.
13 May 2021 (online)
Georg Thieme Verlag KG
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