Trisomy 18. A temporal bone report.

Abstract

Since Edwards first described the trisomy 17-18 syndrome in 1960, the findings in the temporal bones of only four patients with this condition have been reported. They varied widely, ranging from a normal temporal bone, to severe malformations of both the middle and inner ear structures. This study describes the temporal bone findings in a patient with this syndrome. Many of the abnormalities described previously were present as well as the following unreported findings: complete bony atresia of the external canal, an aberrant tensor tympani muscle that did not insert into the malleus but rather attached to a dehiscent area in the Fallopian canal, wide short utricular and saccular ducts, and a widely patent cochlear aqueduct. There was also a developmental arrest of the membranous structures within the cochlea that probably occurred during the 12th week of fetal life.