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

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

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


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

  • Hypo.
  • A sudden violent shake or a jerky 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 regular. However, when jerks or muscle spasms occur frequently or affect more than one area of ​​the body, they can cause problems with everyday 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 involved or its cause.


Exactly why myoclonus occurs is not entirely understood. A myoclonic episode occurs when an abnormal electrical impulse is sent to 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).


Many underlying conditions or disorders are associated with myoclonias, which include:

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


The different types of myoclonias are:

The essential myoclonus:

Any underlying medical condition does not cause it. This type of myoclonus remains stable (unchanged) over time.

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

Opsoclonus is a rare neurological condition whose symptoms include brief and sudden muscle spasms and rapid, irregular eye movements.

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 someone 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.

Myoclonic sensitive to stimulation:

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


The pediatrician will ask about the child’s medical history and general health. 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 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 specific tests to determine 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 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 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 intensity of myoclonic episodes in children with epilepsy.

Sometimes more than one medication is needed to control myoclonus. Anticonvulsant drugs 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. At the same time, 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 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 they must get enough sleep. People whose seizures are caused by the light (photosensitivity attacks) should avoid exposure to blinking lights.

Some recommendations include sitting further away from the video monitors and ensuring enough backlight.