Modified petrosal approach using cosmetic osteoplastic craniotomy with NEURO-SAT guidance.

The petrosal approach has become a routine procedure for petroclival lesions, but there are some disadvantages such as the time-consuming craniotomy during surgery and depressed deformity of the mastoid area after surgery. To solve these disadvantages, we modified the petrosal approach. Before surgery, the three-dimensional points of the sigmoid sinus and semicircular canals are calculated on computed tomography scan and are input to a computer. A single temporooccipital bone flap is made, and the outer table of bone overlying the mastoid is preserved by forming a narrow groove with a small air drill and cutting the outer table with a chisel. After removing these two free bone flaps, mastoidectomy is performed guided by NEURO-SAT (neuronavigation by computer-assisted frameless stereotaxy). The mastoid bone can be drilled out safely and quickly. The two bone flaps are connected and replaced at the end of the procedure. Osteoplastic petrosal craniotomy guided by NEURO-SAT can achieve a quick craniotomy and satisfactory cosmetic result.