Someone else will probably come along with a technical explanation. In the meantime, proper nerve function is necessary for normal muscle function. When nerves are damaged in such a way to make muscles malfunction or cease to function that could be called myopathic neuropathy, I suppose.

Probably the most important thing is to make sure it isn't the central nervous system (CNS) affecting muscles. Sometimes a treatable cause of CNS damage is allowed to continue because it has not been properly diagnosed.

One of the easily treatable causes that is frequently undiagnosed or diagnosed late, is B12 deficiency (usually due to malabsorption).

Please do read my non-commercial site. It will provide you with important basics that most doctors do not know because many medical reference editors have not been doing their jobs on this issue for decades. I was damaged badly, and unnecessarily, becuase of this.

rose