Simply Stated: Neuromuscular Terminology

by Quest Staff on August 1, 2001 - 11:38am

Medical terminology can be a confusing morass of words that sound similar but have different meanings — or words that sound different but mean the same thing.

One way to simplify "Medspeak" is to break it into its basic components. In neuromuscular diseases, those components are often Greek root words.

Here is a quick glossary to help you understand how the names of various neuromuscular diseases arose, and the differences among them.

Atrophy (from the Greek words a, meaning not, and trophe, nourishment)
Definition: a decrease in the size of an organ or tissue (wasting). Common causes of diseases involving muscle atrophy are a lack of nutrients or blood supply or loss of signals from nerve cells.

Dystrophy (from the Greek words dys, meaning abnormal or faulty, and trophe, nourishment)
Definition: a disorder caused by defective "nutrition" or metabolism

  • Muscular dystrophy
    This term is actually a misnomer based on the wrong assumption made many years ago that muscle was being damaged by a lack of nutrients. In modern usage, it refers to a group of genetic myopathies in which a muscle protein is absent, deficient or abnormal.
    The disorders classified as "muscular dystrophies" are myopathies in which a genetic defect results in structural damage to the muscle. Other myopathies involve damage to the muscle's contraction apparatus or energy production system.

Myasthenia (from myo, meaning muscle; a, without; and sthenos, strength)
Definition: muscle weakness or lack of strength. Today, "myasthenia" refers specifically to muscle weakness resulting from faulty communication between nerve and muscle at the place where nerve and muscle meet (the neuromuscular junction).

Myopathy (from the Greek words myo, meaning muscle, and pathos, disease or suffering)
Definition: any disease or abbnormal condition of voluntary muscle

Myositis (from the Greek word myo, meaning muscle, and the Greek suffix itis, meaning inflammation of)
Definition: an inflammation of the muscle, which can result from infection, injury, or attack by the immune system on muscle tissue

Myotonia (adjective myotonic — from myo, meaning muscle, and tonos, tone)
Definition: inability to relax muscles after contraction

Myotonic dystrophy
This genetic disorder involves (but isn't limited to) both myotonia and structural damage to muscles (dystrophy).

Neuropathy (from the Greek words neuron, meaning nerve or sinew, and pathos, disease or suffering)
Definition: any disease of the nervous system. Amyotrophic lateral sclerosis and spinal muscular atrophy, in which loss of nerve cells prevents muscles from working, are neuropathies, as are diseases in which nerve fibers malfunction, such as Charcot-Marie-Tooth and Dejerine-Sottas disease.

Spinal muscular atrophy
The muscle wasting or atrophy in this genetic disorder results from loss of signals from nerve cells in the spinal cord.

"Simply Stated" is a Quest column designed to explain some terms and basic facts about neuromuscular disease.

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