Vestibular Implant System with Internal and External Motion Sensors

Abstract

A partially implantable vestibular prosthesis system is described which includes an external movement sensor that is attachable to the outer skin surface of a patient's head for generating an external movement signal which represents movement of the patient's head. An external transmitter is in communication with the external movement sensor and provides an electromagnetic transmission of an implant communication signal which includes a signal component based on the external movement signal and an electrical power component that provides electrical power for implanted system components. An internal movement sensor is implantable under the skin of the patient's head for generating an internal movement signal which represents movement of the patient's head. And an implant processor also is implantable under the skin and in communication with the internal movement sensor and the external transmitter for generating an implant stimulation signal based on one of the movement signals to electrically stimulate target neural tissue for vestibular sensation by the patient.

Description

[0001]This application claims priority from U.S. Provisional Patent Application 61 / 366,345, filed Jul. 21, 2010, which is incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to implantable stimulation systems, and more specifically to a vestibular implant system with internal and external motion sensors.BACKGROUND ART[0003]A normal ear directs sounds as shown in FIG. 1 from the outer ear pinna 101 through the generally cylindrical ear canal 110 (typically about 26 mm long and 7 mm in diameter) to vibrate the tympanic membrane 102 (eardrum). The tympanic membrane 102 moves the bones of the middle ear 103 (malleus, incus, and stapes) that vibrate the cochlea 104, which in turn functions as a transducer to generate electric pulses to the brain that are interpreted as sounds. In addition, the inner ear also includes a balance sensing vestibular system which involves the vestibular labyrinth 105, its three interconnected and mutually orthogonal semi-circul...

AI Technical Summary

Benefits of technology

[0010]Embodiments of the present invention are directed to a partially implantable vestibular prosthesis system which includes an external movement sensor module that is attachable to the outer skin surface of a patient's head for generating an external movement signal which represents movement of the patient's head. An external transmitter is in communication with the external movement sensor and provides an electromagnetic transmission of an implant communication signal which includes a signal component based on the external movement signal and an electrical power component that provides electrical power for the implanted system co

Problems solved by technology

In some people, the vestibular system is damaged or impaired, causing balance problems such as unsteadiness, vertigo and unsteady vision.

Vestibular implants are currently under development, with one of the initial challenges being the relatively significant amount of power required by the gyroscope / accelerometer arrays used for the movement sensors (gyroscopes and linear accelerometers).

But the power losses for such a transcutaneous supply are roughly a factor of two and there also is an additional risk of the head coil falling off, power being lost, and the patient becoming disoriented and even falling.

A somewhat better solution might be to have an implanted battery supplying power to the implanted movement sensors, but (due to the high power requirements) this approach is likely to require a large battery volume or very frequent re-charging of the battery.

Furthermore, failure of any of the modules of the device would require re-implantation, with consequent risk to hearing and residual vestibular function.

For example, head-worn sensor arrays have been proposed that would be secured by a holding band around the head, but this approach would create an unacceptably high risk of movement of the sensors relative to the head.

Implanted sensor arrays powered via a percutaneous plug have also been proposed, but the serious problems with percutaneous structures are notoriously well-known.

Otherwise the sensor's misaligned input to signal processing, and ultimately to the neural stimulation sites, will lead to a mismatch between real and perceived head movement.

Under specific circumstances this may cause a patient to fall and possibly result in injury.

Due to this degree of radial rotation freedom, this solution is not appropriate for placing an external sensor as part of a vestibular implant system.

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