Temporal Bone Findings in Trisomy D

Temporal bone findings in an infant with trisomy D (13-15) may be summarized as follows: The temporal bones showed multiple anomalies of the middle ear and the inferior part of the inner ear. The facial nerve bifurcated in the petrous portion on the right, and passed through the atretic external ear canal on the left. The stapes were of columellar shape on both sides. Slightly shortened bony cochlea housed a reduced clumped mound of Corti organ with good population of hair cells. The tectorial membrane and otolithic membrane of the saccule were encapsulated with a layer of thin cells. The finding regarding the tectorial membrane suggests that the patient would have had deafness of inner ear origin.