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Types of Myoclonus

Myoclonus: Types list

The list of types of Myoclonus mentioned in various sources includes:

  • Positive myoclonus - sudden muscle contractions
  • Negative myoclonus - sudden muscle relaxations
  • Posthypoxic myoclonus - from hypoxia
  • Action myoclonus
  • Cortical reflex myoclonus - probably a type of epilepsy
  • Essential myoclonus
  • Palatal myoclonus - contractions of the mouth's palate, tongue and related areas.
  • Progressive myoclonus epilepsy (PME) - myoclonus, epileptic seizures, and other serious symptoms walking difficulty, speaking difficulty. PME has various subtypes:
    • Lafora body disease - genetic autosomal recessive, causes myoclonus, epileptic seizures, and dementia
    • PME cerebral storage diseases - myoclonus, visual problems, dementia, and dystonia
    • PME system degenerations - action myoclonus, seizures, and problems with balance and walking
  • Reticular reflex myoclonus
  • Stimulus-sensitive myoclonus - triggered by noise, movement, light, and surprise.
  • Sleep myoclonus - occurs during start of sleep

Types discussion:

NINDS Myoclonus Information Page: NINDS (Excerpt)

The most common types of myoclonus include action, cortical reflex, essential, palatal, progressive myoclonus epilepsy, reticular reflex, sleep, and stimulus-sensitive. (Source: excerpt from NINDS Myoclonus Information Page: NINDS)

Myoclonus Fact Sheet: NINDS (Excerpt)

In its simplest form, myoclonus consists of a muscle twitch followed by relaxation. A hiccup is an example of this type of myoclonus. Other familiar examples of myoclonus are the jerks or "sleep starts" that some people experience while drifting off to sleep. These simple forms of myoclonus occur in normal, healthy persons and cause no difficulties. When more widespread, myoclonus may involve persistent, shock-like contractions in a group of muscles. In some cases, myoclonus begins in one region of the body and spreads to muscles in other areas. More severe cases of myoclonus can distort movement and severely limit a person's ability to eat, talk, or walk. These types of myoclonus may indicate an underlying disorder in the brain or nerves. (Source: excerpt from Myoclonus Fact Sheet: NINDS)

Myoclonus Fact Sheet: NINDS (Excerpt)

Classifying the many different forms of myoclonus is difficult because the causes, effects, and responses to therapy vary widely. Listed below are the types most commonly described.

  • Action myoclonus is characterized by muscular jerking triggered or intensified by voluntary movement or even the intention to move. It may be made worse by attempts at precise, coordinated movements. Action myoclonus is the most disabling form of myoclonus and can affect the arms, legs, face, and even the voice. This type of myoclonus often is caused by brain damage that results from a lack of oxygen and blood flow to the brain when breathing or heartbeat is temporarily stopped.
  • Cortical reflex myoclonus is thought to be a type of epilepsy that originates in the cerebral cortex - the outer layer, or "gray matter," of the brain, responsible for much of the information processing that takes place in the brain. In this type of myoclonus, jerks usually involve only a few muscles in one part of the body, but jerks involving many muscles also may occur. Cortical reflex myoclonus can be intensified when patients attempt to move in a certain way or perceive a particular sensation.
  • Essential myoclonus occurs in the absence of epilepsy or other apparent abnormalities in the brain or nerves. It can occur randomly in people with no family history, but it also can appear among members of the same family, indicating that it sometimes may be an inherited disorder. Essential myoclonus tends to be stable without increasing in severity over time. Some scientists speculate that some forms of essential myoclonus may be a type of epilepsy with no known cause.
  • Palatal myoclonus is a regular, rhythmic contraction of one or both sides of the rear of the roof of the mouth, called the soft palate. These contractions may be accompanied by myoclonus in other muscles, including those in the face, tongue, throat, and diaphragm. The contractions are very rapid, occurring as often as 150 times a minute, and may persist during sleep. The condition usually appears in adults and can last indefinitely. People with palatal myoclonus usually regard it as a minor problem, although some occasionally complain of a "clicking" sound in the ear, a noise made as the muscles in the soft palate contract.
  • Progressive myoclonus epilepsy (PME) is a group of diseases characterized by myoclonus, epileptic seizures, and other serious symptoms such as trouble walking or speaking. These rare disorders often get worse over time and sometimes are fatal. Studies have identified at least three forms of PME. Lafora body disease is inherited as an autosomal recessive disorder, meaning that the disease occurs only when a child inherits two copies of a defective gene, one from each parent. Lafora body disease is characterized by myoclonus, epileptic seizures, and dementia (progressive loss of memory and other intellectual functions). A second group of PME diseases belonging to the class of cerebral storage diseases usually involves myoclonus, visual problems, dementia, and dystonia (sustained muscle contractions that cause twisting movements or abnormal postures). Another group of PME disorders in the class of system degenerations often is accompanied by action myoclonus, seizures, and problems with balance and walking. Many of these PME diseases begin in childhood or adolescence.
  • Reticular reflex myoclonus is thought to be a type of generalized epilepsy that originates in the brainstem, the part of the brain that connects to the spinal cord and controls vital functions such as breathing and heartbeat. Myoclonic jerks usually affect the whole body, with muscles on both sides of the body affected simultaneously. In some people, myoclonic jerks occur in only a part of the body, such as the legs, with all the muscles in that part being involved in each jerk. Reticular reflex myoclonus can be triggered by either a voluntary movement or an external stimulus.
  • Stimulus-sensitive myoclonus is triggered by a variety of external events, including noise, movement, and light. Surprise may increase the sensitivity of the patient.
  • Sleep myoclonus occurs during the initial phases of sleep, especially at the moment of dropping off to sleep. Some forms appear to be stimulus-sensitive. Some persons with sleep myoclonus are rarely troubled by, or need treatment for, the condition. However, myoclonus may be a symptom in more complex and disturbing sleep disorders, such as restless legs syndrome, and may require treatment by a doctor. (Source: excerpt from Myoclonus Fact Sheet: NINDS)

    Myoclonus: Rare Types

    Rare types of medical conditions and diseases in related medical categories:

    Myoclonus: Related Disease Topics

    More general medical disease topics related to Myoclonus include:

    Research More About Myoclonus

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