Differences in Temporal Bone Development in Various Ear Diseases

To investigate the differences in temporal bone development in various ear diseases--bilateral Meniere's disease (n = 13), unilateral Meniere's disease (n = 41), unilateral chronic otitis media (COM) (n = 25), temporal bone fracture (n = 9) and otosclerosis (n = 12)--the following 4 distances on a temporal bone CT slice encompassing the lateral semicircular canal (LSC) were measured by using the NIH Image program. These distances included the minimal distance between the posterior semicircular canal (PSC) and the posterior petrous surface (PPS) (P-P distance), the minimal distance between the PSC and the LSC (P-L distance), the minimal distance between the vestibule and the PPS (V-P distance) and the minimal distance between the PSC and the anterior margin of the sigmoid sinus (P-S distance). Both the P-P and V-P distances showed significant differences among the ear diseases, but the P-L and P-S distance did not. Meniere's disease showed significantly shorter P-P and V-P distance especially in bilateral Meniere's disease than those in COM and otosclerosis (p < 0.05). Affected ears in unilateral Meniere's disease showed a shorter P-P distance than non-affected ears (p < 0.01). In contrast, both ears with otosclerosis showed significantly longer P-P and V-P distances than those in Meniere's disease, COM (p < 0.01) and temporal bone fracture (p < 0.05). COM and temporal bone fracture showed intermediate P-P and V-P distances, without a difference between the affected and non-affected ears. In conclusion, the development of the posterior part of the temporal bone is reduced in Meniere's disease and greatly increased in otosclerosis. These findings by CT may be useful for diagnosing ear diseases.