Evaluating the Pre-Positioning Frame for Robotic Acoustic Neuroma Removal Surgery

Mastoidectomy is a common otologic surgical procedure in which all or part of the mastoid portion of the temporal bone is removed with a surgical drill. The procedure is performed to treat diseases and infections such as mastoiditis and cholesteatoma, and is also performed as one step of other surgeries, such as the facial recess approach for cochlear implantation (CI) or the translabyrinthine approach for acoustic neuroma removal (TANR). The investigators are working on a new medical device to assist specifically with the TANR procedure. The focus of this study is one component of this device, the pre-positioning frame (PPF).

TANR surgery is performed to remove benign tumors on the auditory nerve which can cause severe hearing and balance problems if not removed. The current standard of care is a mastoidectomy, followed by a labyrinthectomy (excision of the labyrinth of the inner ear) to gain access to the skull base, specifically the internal auditory canal (IAC), where tumors are located.

Several critical anatomical structures are embedded in the mastoid bone, including the facial nerve, which controls motion of the face, large blood vessels such as the carotid artery and intracranial continuation of the jugular vein, and the tegmen, which is the boundary between the mastoid and the brain. Surgeons are specially trained to recognize and avoid these structures when drilling. Drilling for TANR surgery often takes several hours due to slow advancement of the drill through hard bone in the labyrinth region. After this drilling is when the most delicate and critical portion of the surgery begins i.e. removal of the acoustic neuroma. The investigators hypothesize that a robot, guided by pre-operative images, can perform the drilling for TANR surgery while preserving safe margins around the critical structures thus enabling surgeons to focus on the delicate, final stage of TANR surgery.

There are several robotic systems available for orthopedic drilling procedures such as joint arthroplasty and resurfacing. These systems include the RIO System (Stryker Mako, Ft. Lauderdale, FL, USA), the ROBODOC Surgical System (Think Surgical Corp., Fremont, CA, USA) and the CASPAR (URS Ortho GMBH & Co. KG, Rastatt, Germany). However, these systems have not been shown accurate enough to perform TANR surgery safely, and rely on expensive image guidance systems to continuously track the patient's position relative to the robot, in order to ensure that the robot-guided drill stays within safe margins.

The investigators previously designed a small light-weight robot that can be attached to the bone of a patient's head, and provide the required accuracy for TANR surgery without an expensive image guidance system.