stuart said:
Here is a very naive question: How do you fiddle with the controller and switch programs?
Not naive at all - it's an excellent question.
Newer Interstims have a two-part control. The first part is a little brick about the size of a small smartphone. This has a magnetic coil in it that communicates with the implant, so it has to be held right over the implant when using it. When I need to make adjustments (which isn't often) I just tuck it in the waistband of my pants to hold it in place.
The second part is a Samsung Galaxy smartphone. It's not one of the high-end models, and it's got a stripped-down set of apps and is locked up so that you can't install anything else on it - yes, I tried! It communicates by Bluetooth to the other part of the controller.
On the smartphone there's an app called My Therapy that I can use to switch programs and adjust the intensity. Mine has six programs, which vary in which of the four contacts in the electrode they use and what frequencies and waveforms they send. The doctor and the Medtronic rep have more advanced software that lets them set up the programs, so they can adjust them to the individual patient, but as the patient I don't get to do that. I mostly adjust the intensity, occasionally switch programs if the effectiveness seems to be diminishing, and I can turn it on and off or put it in MRI mode if I need to.
The way my urologist explained it to me is that the electrode has four contacts at various points along its length. When she implanted it, she put it along the nerve close to where it exits my spine, but the distance from the different contacts can vary, so some are more effective than others. I know that when I switch programs, the sensation can feel different, and can seem to come from different areas of my perineum.
Older Interstims used a purpose-built box to control them, that had a wired connection to the magnetic controller. The new system is really nice, since it's wireless, and nobody questions why I carry around a smartphone (though they do occasionally question why I carry three - personal phone, work phone, and Interstim controller phone!)