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I am running into some commitments on the Day Job that have derailed my ability to get the next series of blogs written, so instead of launching right into the blogs on the "Three-M's" of Multiple Sclerosis (MS), Myasthenia Gravis (MG) and Muscular Dystrophy (MD), I am writing this brief introduction to the topic.
Neuromuscular diseases are basically those disorders in which the majority of damage is to the nerves that carry signals from the brain/spinal cord to the muscles. Essentially, the breakdown in communication can be in the brain (but we have covered those syndromes elsewhere), in the spinal cord, in the nerves as they leave the spinal cord, at the junction between nerve and muscle, or in the muscle itself.
Technically, the catch-all term "muscular dystrophy" refers to the latter category - those diseases or disorders in which theproblem is with the muscles themselves. However, common use includes amyotrophic lateral sclerosis (ALS - Lou Gehrig's Disease, which we'll cover later), MS and MG - particularly when mentioned in a fundraising telethon.
Several significant differences exist with respect to the MD-category of diseases. Again, MD is a catch-all term, but the implication is a disorder of the muscles. MS is a disorder of the nerves, both in the brain & spinal cord and between spinal cord and muscle. The "insulation" that allows nerves to conduct electrical activity very fast over long distances begins to break down in MS. This results in muscle spasm and weakness, but also pain and distorted sensation. MG is specifically a disease of the chemical neurotransmitter receptors at the junction between nerve and muscle. The bodies own immune system attacks the proteins at the junction, preventing the neurotransmitter from being recognized by the muscle, weakening the signals from brain to muscle. ALS is a disease in which the nerve axons themselves begin to die. Each of these disease disconnects the brain from the muscles, and in some cases, the brain from the sensory receptors for touch and position of the body. Muscle weakness, tremors, spasms and pain are the result.
We'll resume the next blog with a look at Multiple Sclerosis, causes, and treatments, followed by Myasthenia Gravis, Muscular Dystrophy, then ALS.