Hi Karen:

When you go in to see the doctor, make sure they do a test called an EMG. This is where they insert a needle into your muscles and can see and listen to the signal. Normal muscles should be silent but in people with disorders causing myotonia, myotonic discharges are often seen.

I say often because on occasion, the muscles of someone with a myotonia causing disorder can be silent, especially if the person doesn't have symptoms that day. Though sometimes when we have no symptom, and EMG will still pick up myotonia.

Be sure they test multiple muscles, and that they do this before they have you do any movements. If they don't find anything, have them cool your muscles and do the test again. Be adamant about this.

If they do find true myotonia, the type can be definitively distinguished with a DNA test. The most common disorders that cause myotonia are:

1. Myotonic Muscular Dystrophy, of which there are two types, type I, and the more mild type II.

2. Myotonia Congenita, which is a chloride channel myotonia and comes in two primary forms which are, the dominant form, also called Thomsens's Disease, the the recessive form, also called Becker Myotonia Congenita, or generalized myotonia congenita.

3. Paramyotonia and Potassium Aggravated/Acetazolamide Responsive Myotonia, which are sodium channel myotonias.

And last, some forms of periodic paralysis, which are also usually on the human skeletal muscle sodium channel.

Another disorder that causes true myotonia is Andersen-Tawil syndrome but that usually involves deformities as well.

There are a few other disorders that cause myotonia like symptoms or symptoms that can be confused with myotonia, for example, thyroid problems, Issac's Syndrome/Neuromyotonia, Stiff Person Syndrome, Brody Myopathy (thought to be very rare), and then we hear from people who have what appears to be myotonia but who's genetic tests don't turn anything up.

Type of Myotonia: Becker

Country: USA