Computer-aided three-dimensional reconstruction and measurement of microfissures

The spatial anatomy of microfissures in the round and oval window areas was investigated in 24 randomly selected normal human temporal bones by our computer-aided three-dimensional reconstruction and measurement method. Microfissures that communicated with the middle ear surface in the round window area were seen in 21 cases (87%) and were located on the posteromediosuperior aspect of the round window niche; whereas microfissures in the oval window area, seen in seven cases (29%), were located at various sites, but mostly in the area below the oval window. Of the 21 microfissures seen in the round window niche, only four were found to be visible through the aperture of the round window niche when viewed from the lateral direction. The mean lengths of the microfissures seen on the middle ear surface in the round and oval window areas were 0.95 +/- 0.66 mm and 0.74 +/- 0.44 mm, respectively. The microfissures in the round window area were significantly longer in individuals 20 years of age and older, than in those less than 20 years (Wilcoxon test, t = 21.5, p less than 0.01); this tendency for microfissures to be longer in older subjects was also found for microfissures in the oval window area. The possible clinical and pathologic significance of these results is discussed.