An Image-Guided Robotic Assistant for Microsurgery of the Inner Ear

Hearing loss is a common chronic condition among older adults. The most common form is sensorineural hearing loss, which is caused by damage to the hair cells of the inner ear. Physicians have little ability to reliably access the complex anatomy of the inner ear and thus are unable to cure the most common forms of hearing loss. Two generations of an image-guided robotic system for targeted, atraumatic needle access to the cochlea of the inner ear were developed. Both systems utilize a custom scanning end-effector that sweeps a single-element ultrasound transducer through a circular arc to construct a two-dimensional scan of the chambers of the cochlea. 150 μm O.D. stainless steel micro-needles were developed that mount alongside the ultrasound transducer. Image-guided needle placement was achieved by selecting a point on an ultrasound image and carrying out a series of global moves of the linear base stages of the robotic system to place the needle tip at the selected point. The first-generation system was used to image a human cadaveric cochlea. These images are, to our knowledge, the first reported application of high-resolution ultrasound to the imaging of the internal structures of the cochlea. In the secondgeneration system, a method for precise calibration of the tip of the micro-needle to