Fasciculations, cramps, twitches, myokimia question.

[JP__0]

  Hello
  Can you explain the difference between, Fasciculations, cramps, twitches and myokimia?  This is mostly for my education, and others who may be interested.  Are these four terms related?
  Tnx!
  JP
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Thanks for your question.  As you are probable aware, all 4 terms refers
to involuntary muscle activity.  Here are the definitions for 3 of them:
Fasciculations: fine, rapid, flickering twitching movements that appear
with contraction of a bundle of muscles.  They are usually not extensive
enough to cause movement of joints, except occasionally in the digits.
They are often irregular and inconstant.  They are usually present at rest,
but they may be brought out, made more rapid, or intensified by light
mechanical stimulation of the muscle.  They are also brought out by fatigue
and cold.
Cramps: localized, involuntary, painful contractions of skeletal muscles.
They may affect a portion of a muscle, an entire muscle, or groups of
muscles that act together synergistically.  The contractions are sustained,
but usually for only limited periods of time.  They are often triggered by
exertion or cold.
Myokymia: spontaneous, transient or persistent movements that affect a
bundle of muscles.  They are usually more "coarse" that fasciculations,
more slow and undulating, sometimes described as a "bag of worms" under
the skin.  They usually are not affected by motion and position.
"Twitch" is an inespecific term describing a small, quick muscle contraction.
I hope this information is helpful.  Best of luck.
This information is provided for general medical education purposes only.
Please consult your doctor regarding diagnostic and treatment options.