HRCT correctly depicted destruction of carotid artery canal in 3 cases, erosion of jugular foramen in 4 cases and facial nerve canal in 5 cases.

Results the sigmoid sinus, internal auditory porus, jugular porus, cochlea, petrous ridge and the most posterior point of the posterior semicircular canal could be markers of surgery.

The variations of the sigmoid sinus included the enlargement of the sinus, the far-advanced sigmoid sinus and high jugular bulb.