Labyrinthine otosclerosis studied with a new computed tomography technique.

Forty-two patients (84 ears) with surgically confirmed otosclerosis were examined with a computerized tomographic scanner (Philips Tomoscan 310) equipped with a table swivel mechanism. All ears were scanned in the horizontal and a new semilongitudinal plane. In patients with an unimpaired bone conduction threshold, a normal labyrinthine capsule was found in all ears except two. Normal bone conduction does not exclude extensive labyrinthine otospongiosis. In cases with bone conduction impairment, the bony labyrinth appeared normal in about half the ears. In the other half, areas of bone resorption were present and a positive correlation was found between the degree of bone loss and the amount of bone conduction threshold loss.