Tapping with impatience
Trying to recover from the fog of anesthesia, I recall there was a video the physical therapist showed me after waking up from the second surgery. What really helped my memory was that my Mom sent that video to me to review. It is still on my desktop, this nine second video. What is the significance of it?
The video was taken in the OR and center stage is my right foot. While playing it you can see the foot moving from pointed to flexed and all of it is possible with the use of the implanted cuff electrode and electrical stimulation. That was pretty awesome to see, but the real excitement around that video is the fact that regardless of what we tried before the surgery we could not get a response while using surface stimulation. In the video, the movement of my foot was all possible due to the implanted nerve cuff technology.
For the past three years, I lost sensation in the right foot and have been struggling with swelling to a point that I could only wear specific sandals and other soft shoes. It was not just the loss of sensation and the added swelling, it was the fact that I slowly lost the ability for my ankle to flex using surface stimulation. Fast forward to today, during surgery the team was able to decompress the nerve below the knee in the front of my right leg. The decompression is a release of excess connective tissue that had formed around it — like carpal tunnel syndrome in my calf. The swelling has gone away. Slowly the sensation is returning too. At first, I felt tingling in my foot and now it has evolved to feeling sensations such as heat and sharper pain.
The day after the second surgery and still in Cleveland, I was summoned to the Motion Study Lab at the Louis Stokes VA Medical Center. We were going to do one more test of the system before I headed home. They tested the system in the OR but this was one more check to make sure everything worked before the next few long weeks of limited activity that I’d have to endure while the incisions healed and the body encapsulates the new hardware.
After being teased by the stimulated movement we saw the day before in the OR, we were eager to see if the responses were the same — and if surface stimulation was any more effective now that the nerve was decompressed. Other members of the research team gather around. These are the people who will be conducting the later laboratory experiments using these new electrodes. The only member missing was the PI (principal investigator). The PT pulls out her tools including a wand with a small surface electrode on the end. The grounding pad is placed on my right knee and she starts to apply stimulation to the muscles to see if they will respond. With every application of the stimulating wand, my foot was pointing down. Not quite what we wanted, nor what the video showed from the OR. At the time, the surgical incision was at the ideal spot to apply surface stimulation to get the foot to flex up. Everywhere around that point, we either had no response or a pointing of the foot. The nerve decompression was able to help my swelling and sensation but it had no effect on the response from surface stimulation.
Time to give up on the wand and try the new implanted electrodes. The engineer brings out the ‘clicky box’ (the external control unit with extra buttons used to test the stimulation). I put the radio frequency transmitting coil on the skin over the new IST-16 and we plug it into the clicky box. We start with the left side that had the good response to surface stimulation prior to surgery. The engineer sets the stimulation to the left gastrocnemius at a low current threshold and turns on the stimulation. The left foot points down, exactly what it is supposed to do. He turns up the juice and the foot points down even more. We try the same procedure for the left tibialis anterior. At both low and high stimulation currents, the foot flexes upward. Both of the new cuff electrodes on the left side are working as we would expect!
We turn to the right leg. Starting with the gastrocnemius electrode. Low current stimulation and then to high, we get a beautiful pointing down of the foot. Now the moment of truth. We test the stimulation for the right tibialis anterior. This is the muscle that did not respond to surface stimulation. We start low and no response. The engineer slowly increases the stimulation parameters and the right foot slowly points to the ceiling and flexes the ankle. The PT then tests the strength of my flexed ankle and she can easily break the flexion by pushing on the top of the foot. The research team is happy and they say it is better than expected. This response just proved that the cuff electrode on the nerve performs better than surface stimulation.
But I didn’t feel the enthusiasm. I guess I was expecting an instant recovery on the right side to get the same response as the left. What I did not realize at the time is that the decompression of the nerve and the placement of the cuff electrode on the nerve are not directly correlated. In other words, the cuff electrode could have been placed around the nerve even with the extra connective tissue and provide the response we were seeing. Maybe the flexing will get stronger with exercise. Considering it was less than 24 hours since the cuff electrode was implanted, my expectations were set for instant performance but not very realistic. Perhaps the decompressed nerve recovers too. The published science tells us that small peripheral nerves regenerate at a rate of about one millimeter per day. But with logical thinking and a little motivation, the burden is now on me to exercise the muscle to rebuild my strength.
Back to the left leg with the good response. We found that if the engineer set the right parameter for flexing the left foot and he rapidly turn the stimulation on and off, then I could tap my left foot on the floor, similar to what people do when they are impatient with something. In walks the PI to the laboratory. Tapping my foot and shaking my index finger, I motion to the PI like “Don’t do that again.” We now have a new stimulation pattern, dutifully called the “scolding” pattern.
So, we know the simulation works and we are getting responses that we need. But the hardest part is the waiting. Now that I’ve seen the new electrodes in action, I have to wait another month until the incisions heal before I can start exercising the ankles and build up to functional use. That is the real tapping with impatience.
Note: The statements and views posted here are of my own and do not reflect those of Case Western Reserve University, the Department of Veteran Affairs, Metro Health Medical Center or the National Institutes of Health along with their representives involved with this program. If you are interested in this clinical trial, please visit https://clinicaltrials.gov and search NCT00623389 or NCT01923662.
