Myoclonus: Symptoms, Classification, Causes, Types, Diagnosis and Treatment

Also known as miclone, it is the symptom of a disease in which a muscle or group of muscles suddenly begins to shake.

When muscle contractions occur frequently or affect more than one area of ​​the body, they can cause problems with normal activities, such as walking, talking or eating.


Myoclonus is a symptom of a disease in which a muscle or group of muscles suddenly begins to shake. Some common examples of myoclonias are:

  • Hypo.
  • A sudden violent shake or a convulsive movement when one is startled.
  • The contractions of an arm or a leg when it begins to fall asleep.

These types of muscle contractions are normal. However, when jerks or muscle spasms occur frequently or affect more than one area of ​​the body, they can cause problems with normal activities, such as walking, talking or eating.


  • Positive myoclonus: it is the contraction of the muscles.
  • Negative myoclonus: is the sudden involuntary (uncontrolled) relaxation of a muscle or group of muscles. If a person is walking or standing, the sudden loss of muscle tone can cause them to fall.

Myoclonus can be classified according to the part of the brain or central nervous system that is involved, or according to its cause.


Exactly why myoclonus occurs is not completely understood. In general, a myoclonic episode occurs when an abnormal electrical impulse is sent to a muscle or muscle groups.

The impulse usually comes from a location in the central nervous system, such as the cerebral cortex, brainstem, or nerves. In some cases, the cause is damage to a nerve or peripheral nerves (those outside the central nervous system).

There are many underlying conditions or disorders that are associated with myoclonias, which include:

  • Epilepsy.
  • Head injury or spinal cord .
  • Brain tumors.
  • Renal or hepatic insufficiency .
  • Chemical or drug poisoning.
  • A long period of time without oxygen ( hypoxia ).
  • Nervous system disorders.
  • Genetic disorders


The different types of myoclonias are:

The essential myoclonus:

It is not caused by any underlying medical condition. This type of myoclonus remains stable (unchanged) over time.

Opsoclonus myoclonus (syndrome of feet that dance and dance):

A rare neurological condition whose symptoms include brief and sudden muscle spasms and rapid, irregular eye movements called opsoclonus.

It can occur in children who have tumors or as a result of a viral infection. Patients may also have problems speaking. Other symptoms include poor muscle tone, irritability or lethargy (feeling tired).

Myoclonic action:

This type can be activated when the person moves or even tries to move. Myoclonus of action is the most disabling type, because muscle spasms can affect the arms, legs, face and voice.

Myoclone sensitive to stimulation:

This type is triggered by external stimuli, such as noise, lights or movement.


The pediatrician will ask about the medical history and general health of the child. You must provide detailed information about your family’s medical history and any medications or toxins (poisons) to which your child may have been exposed.

You should also try to see if the movements occur while the child is resting or moving, and if they seem to be caused by light, sounds, touch or other factors.

The doctor may order certain tests to find out what is causing the myoclonus. These may include:

  • Electroencephalogram, or EEG (a record of brain activity).
  • Electromyography (measures muscle activity and electrical impulses associated with myoclonus).
  • Imaging tests, which include magnetic resonance, computed tomography or positron emission tomography (PET), to detect abnormalities, such as a tumor or injury.
  • Blood tests to see if there is any medical condition that may be causing the spasm.


Treatment depends on what is causing the disorder. The goal is to reduce symptoms with medication.


Anticonvulsant medications, sedatives or tranquilizers may help reduce the frequency and / or intensity of myoclonic episodes in children with epilepsy.

Sometimes more than one medication is needed to control myoclonus. Anticonvulsant medications are usually prescribed to patients with juvenile myoclonic epilepsy.

Clonazepam (Klonopin), a tranquilizer, is effective for some forms of myoclonus.

Valproic acid (Depakene) is the drug of choice for young men with this condition, while lamotrigine (Lamictal) is recommended for young women, as it causes fewer side effects such as weight gain and polycystic ovarian disease .

Other effective anticonvulsant medications include levetiracetam (Keppra), topiramate (Topamax), and zonisamide (Zonegran).

Barbiturates are sedatives that decrease the activity of the central nervous system and can reduce seizures.


Tumors that cause myoclonic activity in children with opsoclonus myoclonus may have to be removed by surgery or treated with chemotherapy and radiation. Oral corticosteroids such as prednisone or adrenocorticotropic hormone may be prescribed .

Behavior changes:

Lack of sleep can increase seizure activity in some children with epilepsy, so it is important that they get enough sleep. People whose seizures are caused by light (photosensitivity attacks) should avoid exposure to blinking lights.

Some recommendations include sitting further away from the video monitors and making sure there is enough backlight.