The Semisitting Retrosigmoid Technique for Removal of Large Vestibular Schwannoma: 2-Dimensional Operative Video

Abstract

INDICATIONS: CORRIDOR AND LIMITS OF EXPOSURE: The retrosigmoid approach in semisitting position (RS-SSP) is a powerful technique for removal of large vestibular schwannomas. 1 It improves extent of tumor resection and nerve preservation. This video shows the case of a 34-year-old man with a large vestibular schwannoma, treated with the RS-SSP technique. The patient consented to the procedure and to publication of his image. ANATOMIC ESSENTIALS: NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: Preoperative MRI and bone window computed tomography are essential for optimal planning. Intraoperative monitoring throughout the surgery includes somatosensory evoked potential (SSEP) and motor evoked potential (MEP) of limbs, facial MEP and electromyography, and brainstem auditory evoked potention. ESSENTIALS STEPS OF THE PROCEDURE: Major steps are (1) positioning of patient in SSP under SSEP recordings, 2,3 (2) ipsilateral retrosigmoid craniotomy, (3) straight dura incision parallel to sigmoid sinus, (4) opening the basal cisterns and gently elevation of cerebellum, (5) identification of Tübingen line on posterior surface of petrous bone, (6) opening and emptying the internal auditory canal (IAC) under nerves preservation, (7) intracisternal tumor debulking, (8) bimanual nerve dissection of cochlear nerve inferiorly and facial nerve medially/ventrally, (9) endoscopic investigation of IAC fundus, 4 (10) plugging the IAC with bone wax and muscle, (11) jugular vein compression before dura closure, and (12) Closure of craniotomy and wound. PITFALLS/AVOIDANCE OF COMPLICATIONS: Correct positioning in SSP is crucial to minimize the risk of air embolism. 3 VARIANTS AND INDICATIONS FOR THEIR USE: Additional resection of suprameatal tubercle allows extension toward the middle fossa and removal of dumbbell-shaped trigeminal schwannomas and petroclival meningiomas. 4