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FIG 1. X-linked congenital deafness. A, Axial CT section (1 mm thick) of the right temporal bone shows a wide IAC. There is absence of bone (arrowhead) at the base of the cochlea allowing it to communicate with the IAC. The cochlea is dysplastic and the modiolus not well seen. B, On the same side, the labyrinthic portion (arrowhead) of the facial nerve is wide. C, Axial CT section of the left temporal bone also shows a wide IAC communicating (arrowhead) with the basal turn of the cochlea. The cochlea is dysplastic, and the modiolus not well seen.