Cochlear implants having impact resistant MRI-compatible magnet apparatus

1. A cochlear implant, comprising:

a cochlear lead including a plurality of electrodes;

an antenna;

a stimulation processor operably connected to the antenna and to the cochlear lead; and

a magnet apparatus associated with the antenna and including a case that defines an inner perimeter and a magnet assembly that is located within the case and is rotatable relative to the case, the magnet assembly including:

a spine having a web and a pair of flanges with respective curved outer surfaces that are coextensive with portions of the inner perimeter of the case and are sized such that there are spine-free gaps along the inner perimeter of the case between flanges, and

first and second magnets on opposite sides of the web.

2. A cochlear implant as claimed in claim 1 , wherein

the web comprises a single rectangular prism.

3. A cochlear implant as claimed in claim 1 , wherein

the spine is substantially I-beam shaped.

4. A cochlear implant as claimed in claim 1 , wherein

each flange includes first and second flat inner surfaces opposite the curved outer surface.

5. A cochlear implant as claimed in claim 4 , wherein

at least a portion of the first magnet is located between the first flat surfaces of the flanges; and

at least a portion of the second magnet is located between the second flat surfaces of the flanges.

6. A cochlear implant as claimed in claim 1 , wherein

the first and second magnets are not rotatable relative to the spine.

7. A cochlear implant as claimed in claim 1 , wherein

the case includes an internal volume defining a height;

the first and second magnets each define a magnet thickness that is less than the internal volume height; and

the spine defines a spine thickness that is greater than the magnet thicknesses.

8. A cochlear implant as claimed in claim 7 , wherein

the spine thickness is less than the internal volume height.

9. A cochlear implant as claimed in claim 1 , wherein

the case includes a top internal surface and a bottom internal surface;

the spine and the first and second magnets include respective top and bottom surfaces;

the top surfaces of the spine and the first and second magnets are offset from one another; and

the bottom surfaces of the spine and the first and second magnets are aligned with one another.

10. A cochlear implant as claimed in claim 1 , further comprising:

lubricious material between the case and the magnet assembly.

11. A cochlear implant as claimed in claim 1 , wherein

the antenna, the stimulation processor and the magnet apparatus are located within a flexible housing.

12. A cochlear implant as claimed in claim 1 , wherein

the spine is formed from different materials than the first and second magnets.

13. A cochlear implant as claimed in claim 1 , wherein

the spine is formed from titanium; and

the first and second magnets are formed from a sintered material.

14. A system, comprising:

a cochlear implant as claimed in claim 1 ; and

a headpiece including:

an antenna, and

a housing and disk-shaped positioning magnet that is rotatable relative to the antenna.

15. A system as claimed in claim 14 , further comprising:

a sound processor associated with the headpiece.