Retrosigmoid Intradural Suprameatal Approach: 2-Dimensional Operative Video

INDICATIONS: CORRIDOR AND LIMITS OF EXPOSURE: The retrosigmoid intradural suprameatal approach is mostly indicated for tumors in the cerebellopontine angle extending toward the Meckel cave and supratentorial regions, most frequently meningiomas and schwannomas. This approach was first established by the senior author in 1982. ANATOMIC ESSENTIALS: NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: Nervous structures: cranial nerves III to XII, cerebellum, and brainstem. Vascular structures: anterior inferior cerebellar artery, posterior inferior cerebellar artery, superior cerebellar artery, basilar artery, vertebral artery, transverse, sigmoid, and petrous sinus, petrosal vein/veins, basilar plexus, and the mastoid emissary vein. Bony structures: petrous bone with internal auditory canal, jugular foramen and suprameatal tubercle, petrous apex, dorsum sellae, and posterior clinoid process. Structures within the petrous bone: vestibule, semicircular canals, and jugular bulb. ESSENTIALS STEPS OF THE PROCEDURE: After a suboccipital retrosigmoid craniectomy in the semisitting position and debulking of the tumor mass in the cerebellopontine angle, extension is achieved by drilling suprameatal tubercle above cranial nerve VII and VIII toward the petrous apex. The extent of bone drilling is tailored for each patient. PITFALLS/AVOIDANCE OF COMPLICATIONS: Avoid damage to cranial nerves, arteries, and veins during drilling, dissection, and tumor removal or by retraction. VARIANTS AND INDICATIONS FOR THEIR USE: In case of extreme supratentorial extensions laterally and dorsally, the opening of the tentorium may be helpful. For inferior extensions toward the upper spinal canal, opening of the foramen magnum and hemilaminectomy of C1 may be necessary.