Tuesday, April 7, 2009

Reflecting on the causes of BR's pain

BR had the SCS controller adjusted yesterday, with a few new programs added. We are still experimenting, trying to find a program that isn't too irritating, yet masks some of the pain.

I asked the technician how BR compared to other patients she's worked with. "Everybody's different. You just have to play around with it." We now have 12 programs with 20 power levels each. That's 240 combinations to "play around with". The vast majority of these create more discomfort for BR than the relief they provide.

She recommended a technique for setting the power level:
  1. Slowly increase the power until the sensation is noticeable

  2. If the sensation is uncomfortable, back the power down a notch or two
This would be fine except for the fact that BR is experiencing "sensation echoes." An unpleasant sensation will replay in his head for up to a minute or more after the stimulus has been removed. This turns the recommended technique into a form of torture that could get someone a court date at The Hague.

I'm still wondering if a cervical placement of the stimulator leads wouldn't have been more effective. Evidence is mounting that progressive MS is a result of damage to the nerve axon, which gets exposed after the myelin sheath is stripped away during the initial MS attacks. Like a metal wire without insulation and exposed to the elements, the wire eventually starts to corrode. Signals get weaker and degrade as the corrosion gets worse. Eventually the signals don't get through at all.

I found this video from the Mayo Clinic on YouTube. It talks about a couple of enzymes that may be responsible for the axon damage in people with progressive MS.



In the telecommunications world, there is an effect called electrical signal reflection.
Signal reflection occurs when a signal is transmitted along a transmission medium, such as a copper cable or an optical fiber, some of the signal power may be reflected back to its origin rather than being carried all the way along the cable to the far end. This happens because imperfections in the cable cause impedance mismatches and non-linear changes in the cable characteristics.
Could it be that the pain signals we are trying to mask are actually impulses that started in the brain and were reflected back at the point of axon damage? This might explain a couple things.
  • Stress and anxiety increase BR's pain levels. Research has shown that accompanying anxiety, "Almost invariably there are physical disturbances -- palpitations, tremulousness, sweating, diarrhea, etc. -- due principally to overactivity of the autonomic, particularly the sympathetic, nervous system, and to increased output of catecholamines by the adrenal medulla." In theory, when this increased activity hits the damage, it reflects back to the brain as a pain signal.

  • The sensation echo could be caused by two or more damaged axons along a single neural pathway. The signal bounces back and forth between the points of damage, losing strength over time.
Of course, I'm not a doctor. My training is in engineering and computer science. But still, my instincts tell me that if the stimulator leads were placed in the cervical spine between the brain and the axon damage, we might have a better chance of scrambling the pain signal with fewer sensation echoes.

6 comments:

Anonymous said...

Steve, I'm not a doctor either...but for a "lay person", your understanding of the medical vocabulary is quite something. And I suspect your engineering / computer background lends a good understanding of the similarities of neural pathways and electrical currents.

I would tend to agree with your assessment of the treatment, based on your understanding of it, and would further suggest possibly relaying your thoughts and concerns to BR's doctor. As my mother would have said, (rather simply, I admit)... "The worst they can do is tell you no...they can't eat you."

Either way, I'll keep you in my prayers that you find some resolution to this...and soon.

Susanne

Kim said...

Steve, what has been the reaction when you share your research with BR's care team? Are they generally receptive to your findings, or are they dismissive because you're not the supposed expert on the subject? Is there a way to get them to really listen to you? As Susanne said, your ability to make sense of the research is impressive, and you sound more and more like an expert on MS. Do they take you seriously? If not, can you address that in some way? Is there a patient advocate at any of the clinics/hospitals? Perhaps that person could support your efforts.

steve said...

In this case, I explained my concerns about lead placement to both the neurologist and the pain doctor who performed the procedure. The pain doctor agreed that a cervical placement might be necessary, and even scheduled the procedure to be performed the same day if he couldn't get good coverage from the lumbar placement.

On the way out after the procedure, he told me that he got good coverage from the lumbar procedure, and that the cervical procedure wasn't necessary. Unfortunately, coverage means any sensation over the affected area, and not effective pain control.

Herrad said...

Hi Steve Hi BR,

Steve your reasoning sounds very good, hope the docs will tr y your suggestion.

Hoping for pain relief for you BR.

Thinking about you both.

Love,

Herrad

Kim said...

So on the one hand, the doctor agrees with you, but on the other, he/she doesn't actually do anything about it beyond agreeing with you. Mind boggling. How do you guys deal with this over and over again? I'm frustrated by all this from hundreds of miles away!

Would BR be able to go through the procedure again if it was warranted? Would insurance cover it? I am probably missing an important piece of information about how MS works, but it seems odd that they wouldn't do both placements given what the care team knows of BR's pain issues.

I know, I know, preaching to the choir, right?

Bobrobert said...

Kim -

Girl, I don't know . . .