Translabyrinthine Approach to Vestibular Schwannomas

Abstract

The most common indication for translabyrinthine (TL) surgery is a vestibular schwannoma of any size in an ear with nonserviceable hearing. Small to medium tumors measuring up to 2 cm in diameter with good hearing are ideally suited to a retrosigmoid approach with hearing preservation and endoscopic assistance depending on tumor characteristics. The approach may be combined with a retrosigmoid technique by ligating the sigmoid sinus if it is not dominant in certain tumor cases. In larger tumors, with a wide inferior brain stem attachment, a high jugular bulb can limit the surgical exposure. The TL procedure should be performed in a large operating suite that provides ample room for equipment, including the operating microscope, intraoperative monitoring systems, neuronavigation, dissection tools, including pneumatic drills, and cavitating ultrasonic aspirators. All soft tissue should be removed from the lateral cranial base to completely expose the mastoid process, digastric ridge, external auditory canal, and retrosigmoid region. All bone can be removed from the sigmoid sinus and the sinus can be gently bipolared to contract and retract it posteriorly. The sigmoid sinus must be fully decompressed and mobilized posteriorly and all of the bone over the middle fossa dura, posterior fossa dura, and petrosal sinus, need to be removed to gain as much exposure as possible. Usually the upper limit for the exposure is the superior petrosal sinus and middle fossa dura, but the TL approach can be extended superiorly. New techniques in tumor debulking, sharp dissection, and intraoperative facial nerve monitoring have led to excellent rates of facial nerve preservation.