Hi Marlene --
The only thing I can tell you is what has happened with me. Like you, I was on statins for years before they discovered the neuromuscular disease. One of the first things the doctors did was take me off of statins for about a year to see if it made any difference in the weakness or how I felt.
It didn't. Nothing changed one bit. Because of a SERIOUS history of heart disease in my family, it was decided that I really needed to stay on the statins.
Over the course of the years, I have been taken off again or the type of statin changed. But in the end, all my doctors have concluded that the statin was not having any impact on my situation so I continued taking them.
Right now, I take 40mg of Simvastatin (generic for Zocor). I was switched to this, per my request, from Lipitor 20mg because of the cost. I can get 90 days of Simvastatin for about $9, where I was paying $117 for the Lipitor (since there's no generic for it).
I know this doesn't answer your question, but I hope it helps to know that there are others out here dealing with the same thing -- what to do about cholesterol medication when you suffer from a neuromuscular disease.