Re: Question about imbalance..... Urinary retention and bowel retention
Pam, sorry your family has been through so much with the health problems!
Do you have DNA results on you and your daughter? It would be very unusual to have both CLCN1 and SCN4A mutations, although not impossible.
What you're describing sounds much more like a sodium channel mutation like paramyotonia congenita (which is usually more serious and progressive than hyperKPP).
It's very possible that issues like the gastroparesis, urinary retention or vertigo are totally separate conditions. I had gastroparesis and vertigo from a viral infection, not MC. There are things like Meniere's Disease that can cause imbalance and dizziness if it's cyclical. The headaches and reading problems may be related to MC because it does affect the ocular muscles. One of my daughters had trouble with that and got some good therapy that helped (things like putting colored acetate over what she was reading).
I would look for a specialist in Myalgic Encephalitis for your daughter to see if the virus caused some nerve damage. It is strongly associated with chronic fatigue, usually after contracting mono or a similar virus. ME Association
I would also ask for a second opinion about the gastroparesis. I can't believe a doctor would say she might need to have her bowels removed in the future. There are several options for treating it. One of my friends' daughters has a device that works by waving a magnet over the implant. Urinary retention is not caused by any of the myotonias that I'm aware of. Both that and the gastroparesis are probably caused by damage to the nerves in the spine, probably around the lower thoracic area. If she hasn't had an MRI, I would request that to check for narrowing or a tumor. If she's been injured there can be axonal damage which keeps the nerve impulses from being transmitted.
So I guess to answer your question, some of the symptoms you're describing MIGHT be related to myotonia, but there is definitely much more going on. It may be another genetic condition or something caused by environmental exposures. But definitely don't let the doctors blame it all on the MC.
The best doctor for you to see in London is Prof. Michael Hanna. If he is not the one your appointment is with, ask for a referral because of your unique family presentation. If anyone can sort it out, it would be him.