Computer-aided three-dimensional reconstruction and measurement of facial canal dehiscence

Location, shape and dimensions of the dehiscence in the facial canal to the middle ear space were studied in 20 temporal bones obtained from 19 individuals aged 1 day to 72 years at death by using our computer reconstruction and measurement method. The most frequent site of dehiscence was the oval window area (70%), particularly in its posterior half and on the inferior to inferomedial aspect of the canal. The shape of the dehiscence tended to be oval in the oval window area, but rather irregular in the other areas. The dehiscence ranged from 0.4 to 2.64 mm in length, from 0.12 to 1.59 mm in width, and from 0.03 to 1.87 mm2 in surface area. Proximity of these dehiscences to the field of otological surgery is stressed.