What is Myoclonus?

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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 27 September 2019
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Myoclonus is a term used to describe the jerking or twitching of a muscle. Healthy people experience myoclonus on a regular basis and it can also be the symptom of an underlying medical condition which requires medical attention. This involuntary muscle movement can take a wide variety of forms, appearing in any muscle in the body at any time, depending on the underlying cause of the myoclonus.

Some examples of normal myoclonus include hypnic jerks, which often happen as people are falling asleep, and hiccups. This type of myoclonus is not a cause for concern, although it can be startling or irritating. People can also experience random twitches and muscle spasms which are not associated with a medical issue. An athlete, for example, might twitch after a heavy workout, and sometimes the nervous system experiences a random glitch which generates a twitch for no apparent reason.

In people with nervous system disorders, myoclonus can sometimes be a tell-tale symptom. Conditions like head trauma, brain damage, and progressive neurological disorders such as Alzheimer's disease and epilepsy may have myoclonic jerks among their symptoms, as can a range of other neurological problems. Muscle twitches are also associated with kidney, liver, and heart problems. Abnormal myoclonus tends to appear at greater frequency, with more intensity, or at unusual times, and it may involve a series of muscle spasms, rather than a single twitch or jerk.


When twitching or jerking develops suddenly or feels abnormal, patients should seek medical attention to find out what is going on. Sometimes it can be difficult to differentiate between normal myoclonus in healthy people, and muscle jerks which indicate an underlying pathology which has not been diagnosed. In either case, it's a good idea to consult a neurologist. The neurologist can interview the patient to learn more about the myoclonus, and he or she may recommend testing which can be used to determine the underlying cause, such as EEGs of the brain, along with imaging studies like CT scans and MRIs.

If a neurologist cannot find a cause for a myoclonus but the twitching is irritating, he or she may have medications to recommend which could help the patient manage the issue. In patients with neurological or other disorders which are causing myoclonic jerks, addressing the underlying condition can resolve or reduce the twitching. Neurological conditions may not necessarily be curable, but their symptoms can often be managed with medication, surgery, and other treatments to keep patients more comfortable.


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Post 3

@Iluviaporos - Another episode they had was a woman who had severe hiccoughs and it turned out that she had damaged some part of her lungs and she ended up passing away. So, severe hiccoughs which you can't get rid of are not always the harmless kind of myoclonus.

I haven't had hiccoughs in a long time, at least not badly. I figured out how to stop them from happening. If you really pay attention to what part of your body is tightening every time you hiccough, you can relax it in the same way you can relax a cramped muscle.

Once you get into the habit of it, they don't even seem to happen all that much anymore, although I noticed I occasionally get them after I go jogging.

Post 2

I remember seeing an episode of Grey's Anatomy where they had a patient who was a three year old girl who had a myoclonus in the limbs on one side of her body. It turned out that she was basically having an almost continuous myoclonus seizure on that side and that it was because one side of her brain had died.

It was pretty amazing actually because it was based on a real case. They removed the dead side of her brain and the rest of it simply learned how to compensate for the missing areas.

The brain is really an adaptable and incredible thing.

Post 1

I've heard one theory of why people get hypnic jerks is because it's left over from when we were still living in trees.

A hypnic jerk is when you are falling asleep and suddenly feel like you are falling. I know when it happens to me, often it involves a kind of half daydream where I suddenly step off a curb or a stair unexpectedly. You get that same little shock you would if that actually happened, and it jerks you awake.

The theory goes that this is what would happen if you were in a tree, perhaps hiding from from a predator, and you suddenly started to fall asleep. Of course, if you were more used to the sensation of falling from a tree than stepping off a curb, that's what your mind would bring up, and presumably the effect would be to make you clutch at a branch.

I can see why that would have evolutionary advantages!

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