Julie, did you have DNA testing or an EMG to confirm the myotonia? Many doctors call all MC Thomsen's and don't know that there are two types as well as the sodium channel myotonias. That's interesting about the Savella. Several people have told me they saw improvement on SSRIs like Prozac or Zoloft.
Does your mother take statin drugs for high cholesterol? That can cause Dermatomyositis and it can cause myotonia to become much worse. It is definitely contraindicated for us as well as the quinolone antibiotics like Cipro and Levaquin which are often given for UTIs in the elderly.
I had a DNA and nerve conduction test. My mother had never been tested. Her brother's daughter and grandson has Thomsen Myotonia. Therefore, my mother has to be the carrier. No one on my Dad's side has Myotonia. My mother does not have any symptoms of myotonia.
I do believe that my mother takes medicine for high cholesteral.
Judy, my mutation is G230E and myotonia runs all through my mother's family, but she never had symptoms. Her doctor was very surprised when she showed up with myotonic discharges on the EMG.
This is a link to an earlier post where I listed all the contraindicated medications for cholesterol treatment and high blood pressure:
Hope that helps. She may be a slow metabolizer genetically, or her age may be causing her to metabolize medications more slowly which can cause elevated blood levels and more severe side effects.