What causes NDM
Non-dystrophic myotonia, or NDM, refers to a group of diseases that affect muscles. To understand what causes NDM, we must first understand how muscles work.
How do muscles work?
Muscles work by contracting and relaxing. To do this, they need electrical signals from the brain, which travel along nerves until they reach the muscle. When the signal reaches the muscle, it is dependent on microscopic channels in the muscle cell walls to translate the signal and trigger the muscle to contract. Normally, when the brain stops sending signals to the muscle, the muscle relaxes. This entire process happens in milliseconds.
“You often just get used to things in order to disguise the handicap. You don’t want to be reminded about it the whole time.”— PD, Becker myotonia
What causes NDM?
In NDM, a genetic mutation causes a defect in either of two types of ion channels, which play roles in regulating the contraction and relaxation of muscles – these channels are called sodium (Na+) and chloride (Cl–) ion channels.1,2 Defects in these channels mean that the electrical signal continues to trigger a contraction or that muscle relaxation is delayed, both of which keep muscles contracted for longer than they would normally.
Different types of NDM are caused by different mutations in different ion channels; it is important to understand which type of NDM you have to help manage your symptoms better.
- Hahn C, Salajegheh MK. Iran J Neurol 2016;15:46–53
- Matthews E et al. Brain 2010;133:9–22