Atraumatic surgical approach to the cochlea with a micromanipulator.

CONCLUSIONS: Our design and preliminary results show that the the micromanipulator could be a great help to the surgeon in the atraumatic surgical approach to the lateral wall of the cochlea at the promontory. OBJECTIVES: Hearing preservation in cochlear implant opens new frontiers in the treatment of sensorineural hearing loss. To preserve the membranous labyrinth intact, new surgical tools are needed, either for cochlear implantation or for other applications. The objectives of this study were to design and test a micromanipulator coupled to a drilling tool for the atraumatic exposure of the spiral ligament. The micromanipulator is designed to increase precision when drilling the otic capsule bone. MATERIALS AND METHODS: A group from the University of Navarra worked on the device design -- based on a compliant mechanism -- and in vitro test. The components and functioning of the micromanipulator are described. It was tested in 10 formalinized temporal bones after a mastoidectomy, a posterior tympanotomy, and a transcanal tympanotomy were performed. The micromanipulator was placed over the cranial surface, and used to expose the endostium, anteriorly to the round window niche. RESULTS: A combined approach through the external auditory canal was feasible, together with a posterior tympanotomy to visually control the work and make complementary manoeuvres. Drilling was easy, and visual control through the posterior tympanotomy was excellent. A high degree of drilling precision was achieved. A little disruption of the membranous labyrinth was found only in the first bone of the series.

Micromanipulator for enhancing surgeon's dexterity in cochlear atraumatic surgery.

The hybrid stimulation in cochlear implants requires changes in the design of electrode arrays. A new generation of flat electrode arrays that does not damage the cochlea is being developed. For the insertion of these flat array electrodes a groove must be milled in the antero-inferior area of the round window niche. Even for the most experienced surgeon, it is very difficult to carry out this operation without damaging the cochlea. That is why external help is needed. For helping the surgeon to mill the groove, a compliant mechanism based micromanipulator has been designed, manufactured and tested. A surgical milling tool is attached to a specially designed compliant mechanism and positioned properly along the auditory canal. The compliant mechanism guides the motion of the surgical tool, keeping tactile feedback and enhancing the dexterity of the surgeon for an accurate milling of the groove.