What is a Myoclonic Jerk?

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  • Written By: Rachel Burkot
  • Edited By: Bronwyn Harris
  • Last Modified Date: 19 August 2019
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A myoclonic jerk is an involuntary twitch of a muscle or muscles. It often occurs before a person falls asleep and is usually harmless, but it can also be a symptom of a serious disease. The jerking is either the result of a muscle contraction or the lapse of a contraction. Positive myoclonus is called a contraction, while negative myoclonus is called a relaxation.

Myoclonus refers to a symptom, not an illness, and myoclonic activity can occur in healthy people with no other health effects. When a myoclonic jerk occurs before a person drifts into sleep, it is similar to a hypnic jerk. Studies have been done as to why these twitches occur, with no conclusive results. Some doctors say the myoclonic twitch is the body’s way of giving off one final burst of energy before settling into a resting pattern for the next several hours. Others believe hypnic jerks are the body’s natural reaction to the loosening of muscles as the body prepares to let go.


These jerks can occur infrequently, at random or in a regular pattern. Some people who experience these twitches find their muscles releasing into a jerk every 30 seconds for hours at a time. Other people may experience such a jerk once during the night and never feel it again. A myoclonic jerk is associated with prehistoric archetypes, which explains the falling sensation that leads to the body’s jerky reaction. A jerk is sometimes accompanied by either a dream or a vision of falling out of a tree or down a hill, and the twitch that results is the body’s natural mechanism for coping with that sensation.

Besides the sleep jerk, another type of myoclonic jerk is the hiccup. Hiccups disturb the regular movement of the diaphragm, which sends the body’s system into a resulting spasm known as a hiccup. Of course, hiccups are perfectly natural and are nothing to worry about. Often, however, these jerks can be a sign of a neurological or peripheral disease, such as multiple sclerosis, Alzheimer’s disease, Parkinson’s disease and epilepsy.

In severe cases of myoclonus, a person’s daily activities, such as movement and speaking, can be impaired. Myoclonic seizures can occur in epilepsy patients, and other diseases such as Parkinson’s and Alzheimer’s can originate from a lesion of the cortex, subcortex or spinal cord and will be aggravated by myoclonic jerks. When this type of jerk is not a symptom of disease, it requires no special treatment or care. When a patient begins to experience the symptoms of something more severe, drugs such as barbiturates, phenytoin and primidone can slow down the nervous system and keep the illness at bay.


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Post 3

I started having the jerks after an epidural shot. I thought it might be related to Parkinson's, but was probably the shot. Going to have an EEG to fond out. Do not ever get an epidural for a back injury.

Post 2

My mom had this happen while we were coming back from a long trip in the car, and we thought she was dying. Glad to find out what it was. She is 90 and has dementia for about three years now.

Post 1

My husband has had a defibrillator/pacemaker implant for three years. He has suffered through the unit firing seven times. He recently started a new medication for depression, vilazodone HCL, 40 mg level, for the past eight days.

Twice in the last 10 days, he was jolted out of sleep, believing his defibrillator had fired, but according to the monitoring system, it has not fired. There was no pain, but he thinks there was a bright flash that jerked him awake and sitting up. Needless to say, it's frightening. Could his new medication cause this? Is this just a "sleep jerk" thing?

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