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Muscle Fasciculations vs Myoclonus in patients with EDS and Dysautonomia


Many people suffering from hEDS, especially those diagnosed with dysautonomia, complain of spontaneous involuntary muscle contractions, part of them during or after physical activity that can be either mild or strenuous. In most cases, this phenomenon becomes annoying at best and, in other cases, even troublesome and restricts simple activities such as writing, holding a cup, walking, etc.

To understand the significance of this phenomenon, one must first understand the course of muscle contraction, and we will explain this in the most basic and straightforward way.

How muscles contract

Every muscle that belongs to the locomotor (movement) system contracts voluntarily following an electrical command that begins in the brain, passes through the spinal cord, and ends in a peripheral nerve. The peripheral nerves eventually reach the muscle cells, and release the nerve impulse, causing the breakdown of energy within the muscle cells, inducing the cells to contract. Stopping the nerve stimulus stops the muscle contraction, resulting in muscle relaxation and "recharging" of the cells. This stage is called "repolarization."

In general, we say that there is no contraction without a command (stimulus) from the brain.

Myoclonus usually occurs at the Central Nervous System (brain and spinal cord level), i.e., not in a single nerve cell. The causes can be varied, from drug use, physical injury, neurological disease, and more.

Myoclonus is a sudden, brief shock-like movement of a joint, the fastest and briefest of all hyperkinetic movement disorders (Blindauer, 2004; Espay and Chen, 2013). Movements are caused either by muscle contraction or negative myoclonus, by muscle inhibition (Blindauer, 2004).

Myoclonus appears when there is over-stimulation of the affected area in the brain, and not just in the muscle that contracts, so it is more challenging to diagnose and treat. Factors that affect the onset of myoclonus can be:

  • Changes in blood pressure.

  • Change in medication.

  • Use of alcohol and drugs.

  • Sudden change in posture.

  • Gradual exposure to environmental changes, such as altitude and temperature.

Fasciculations, on the other hand, cause visible twitches of a portion of an individual muscle. As opposed to myoclonus, they are too small to cause movement of a joint, although large distal fasciculations may displace a digit.

Fasciculation is a sudden and momentary contraction of a motor muscle that lasts for several seconds in a row for several minutes to several hours. This contraction is caused by a single peripheral nerve stimulus and is not related to the central nervous system. A physiological change at the nerve level causes damage to the "repolarization" system mentioned earlier, meaning continuous muscle stimulation. This phenomenon is not dangerous, but it can feel strange and interfere with a simple activity. Unlike myoclonus, fasciculation increases at rest.

In neurological patients and patients with ESD and DYSAUTONOMIA, Benign Fasciculation Syndrome is one of these patients' symptoms.


There is no specific treatment for this phenomenon, other than prevention and preservation. Medications can be combined to reduce the cramps, but in most cases, this step will be given if the cramps impair the quality of life or endanger the joints, and not in BFS.

Physical therapy includes stretching of the peripheral nerves, passive mobilization of the joint, and in some cases, work on soft tissue can also help.

Maintaining proper hydration can also prevent the mineral imbalances that cause damage to the nerve cell's physiology, but there is no unequivocal evidence to support this theory.


This article addresses involuntary contractions in patients with EDS AND DYSAUTONOMIA, and emphasizes that this is not a dangerous phenomenon. In most cases, the diagnosis will be BENIGN FASCICULATION SYNDROME, since most patients do not suffer from central nervous system injury but only peripheral injury. Although there is no dedicated treatment, there is pharmacotherapy given in exceptional cases where there is danger or significant impairment of life quality. Still, most of the treatment and prevention is done in physical therapy by stretching the peripheral nerves.

Ther Adv Neurol Disord. 2011 Jan; 4 (1): 47–62.

doi: 10.1177 / 1756285610395653

PMCID: PMC3036960

PMID: 21339907

Myoclonic disorders: a practical approach for diagnosis and treatment

Clin Neurophysiol Pract. 2018; 3: 22–23.

Published online 2017 Dec 20. doi: 10.1016 / j.cnp.2017.12.001

PMCID: PMC6134193

PMID: 30215002

Differentiating fasciculations from myoclonus in motor neuron disease

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