one of my daughter and I have recently been confirmed as having Myotonia Congenita and my daughter also has hyperkalaemic periodic paralysis.
Over the past two years one of my sons has had problems with imbalance which results in him having lack of concentration... when he concentrates on e.g. reading, for a few minutes he gets headaches which get worse and cause him to feel ill and sick. his imbalance is currently being helped with taking Cinarazine. for the first year the problems would last between 1 and 3 weeks every couple of months but he has had them continually since October 2013. He had the genetic blood test on Tuesday and so have to wait 2 months for the results.... the reason they have done the test is because he recently had an EMG which showed the same result as his sister.
Now, my writing to you is to ask, is the imbalance a known symptom of Myotonia Congenita because our consultant said he hasn't seen / heard of any cases that he has dealt with / read about that includes this symptom; although he's not ruling it out because it's an extremely rare condition and he hasn't seen many cases. Having read your thread I thought you may be able to help.
I look forward to your response