内耳道断層X線撮影における横稜(Crista Transversa)の計測

The crista transversa was evaluated on tomographic X-rays of the internal auditory canal in 200 subjects (400 petrous bones) in an attempt to ascertain whether they are useful in diagnosis of acoustic neurinomas.1) In 137 cases (68.5%) both cristae transversae were visible, in 17 cases (8.5%) one was visible, and in 46 cases (23%) no crista transversa could be seen.2) All the cristae transversae were in the upper half of the internal auditory canal fundus.3) The average length of the crista transversa was 2.93mm (S. D. 1.40mm).4) The average difference in the length of the bilateral cristae transversae was 0.92mm (S. D. 0.93mm), and in 94% it was less than 2.5mm.Therefore, we suggest three criteria for suspected acoustic neurinomas.1)One crista transversa is not visible.2)The crista transversa is in a much lower or higher position than normal.3)There is a difference of more than 3mm between the right and left cristae transversae.