Essential myoclonus (benign hereditary essential myoclonus)

Myoclonus

a brief, involuntary, irregular (no rhythm) twitching (different from clonus, which is rhythmic/regular) of a muscle or group of muscles.
It describes a medical sign and is usually not a diagnosis of the disease. These myoclonic jerks
,
jerks
, or seizures are usually caused by sudden muscle contractions (
positive myoclonus
) or brief interruptions in contraction (
negative myoclonus
).
They most often occur during sleep (hypnotic moron). Myoclonic jerks occur in healthy people and sometimes happen to everyone. However, when they occur more persistently and become more widespread, they may be a sign of various neurological disorders. Hiccups are a kind of myoclonic impulse, especially affecting the diaphragm. When a spasm is caused by another person, it is known as a provoked spasm
. Shaking attacks in infants fall into this category.

Myoclonic jerks can occur individually or sequentially, with or without a pattern. They may occur infrequently or many times every minute. Most often, myoclonus is one of several signs of a wide variety of nervous system disorders, such as multiple sclerosis, Parkinson's disease, dystonia, Alzheimer's disease, Gaucher's disease, subacute sclerosing panencephalitis, Creutzfeldt-Jakob disease (CJD), serotonin toxicity, some cases of Huntington's disease, some forms of epilepsy, and sometimes intracranial hypotension.

In almost all cases where myoclonus is caused by a disease of the central nervous system, it is preceded by other symptoms; for example, in CJD, it is typically a late clinical feature that occurs after the patient has already begun to exhibit significant neurological impairment.

Anatomically, myoclonus may occur due to damage to the cortex, subcortex, or spinal cord. The presence of myoclonus over the foramen magnum effectively excludes spinal myoclonus; further localization depends on further studies with electromyography (EMG) and electroencephalography (EEG).

Types

The most common types of myoclonus include action, cortical reflex, essential, palatal, those seen in progressive myoclonic epilepsy, reticular reflex, sleep and stimulus.

Forms of epilepsy

• Cortical
  myoclonus reflex is considered a type of epilepsy that occurs in the cerebral cortex—the outer layer or “gray matter” of the brain responsible for most of the information processing that occurs in the brain. In this type of myoclonus, cramps usually affect only a few muscles in one part of the body, but cramps involving many muscles can occur. Myoclonus of the cortical reflex may increase when patients try to move in a certain way or perceive certain sensations.
• Essential
  myoclonus occurs in the absence of epilepsy or other obvious abnormalities of the brain or nerves. It can occur randomly in people with no family history or among members of the same family, indicating that it can sometimes be hereditary. Essential myoclonus usually remains stable without increasing in severity over time. Some scientists suggest that some forms of essential myoclonus may be a type of epilepsy without a known cause.
• Juvenile myoclonic epilepsy
  (JME) usually consists of twitching and twitching of the muscles of the upper extremities. These can be arms, shoulders, elbows and very rarely legs. JME is one of the most common types of epilepsy and can affect one in every 14 people with the condition. These seizures usually occur soon after waking up. The onset of JME can be seen during puberty in most patients. Taking medications that also treat multiple types of seizures is usually the most effective form of treatment.[1]
• Lennox-Gastaut syndrome
  (LGS), or childhood epileptic encephalopathy, is a rare epileptic disorder accounting for 1–4% of all childhood epilepsies. The syndrome has much more severe symptoms, ranging from multiple seizures daily, learning disabilities, and electroencephalogram (EEG) abnormalities. Younger age at seizure onset correlates with a higher risk of cognitive impairment.
• Progressive myoclonic epilepsy
  (PME) is a group of diseases characterized by myoclonus, epileptic seizures, tonic-clonic seizures, and other severe symptoms such as problems walking or speaking. These rare disorders often worsen over time and can be fatal. Research has identified at least three forms of PME. Lafora disease is inherited as an autosomal recessive disorder, meaning that the disease occurs only when a child inherits two copies of the defective gene, one from each parent. Lafora disease is characterized by myoclonus, epileptic seizures, and dementia (progressive loss of memory and other intellectual functions). The second group of PME diseases, classified as brain storage diseases, typically includes myoclonus, vision problems, dementia, and dystonia (sustained muscle contractions causing twisting movements or abnormal postures). Another group of PME disorders in the class of systemic degenerations is often accompanied by myoclonus effects, seizures, problems with balance and walking. Many of these PME diseases begin in childhood or adolescence. Treatment is usually not successful over a long period of time.
• Reticular reflex
  myoclonus is considered a type of generalized epilepsy that occurs in the brain stem, 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 entire body, affecting muscles on both sides of the body at the same time. In some people, myoclonic jerks occur only in one part of the body, such as the legs, but all the muscles in that part are involved in each jerk. Reticular reflex myoclonus can be caused by either voluntary movement or an external stimulus.

Diaphragmatic flutter

A very rare form includes diaphragmatic flutter, belly dancer syndrome,[2]:2 or Van Leeuwenhoek's disease. It was first described by Anthony van Leeuwenhoek in 1723, who suffered from it.[2]:2 The condition is characterized by verbal communication that sounds like shortness of breath. hiccups.[ quote needed

] These muscle spasms can occur dozens of times a day. The rate of contraction of the diaphragm ranges from 35 to 480 contractions per minute, with an average rate of 150.[2]:3 Research suggests that possible causes include disturbances in the central or peripheral nervous system, anxiety, malnutrition, and certain pharmaceutical drugs. No single treatment has been shown to be effective, although blocking or crushing the phrenic nerve may provide immediate relief when pharmacological treatment has failed.[2]:11

Only about 50 people in the world have been diagnosed with diaphragmatic flutter. One case is Chaz Moore of Colorado Springs, Colorado, who was interviewed by CNN's Dr. Sanjay Gupta. The patient tried several medications, of which only medical marijuana worked.[3][4]

Other forms

• The action
  of myoclonus is characterized by muscle twitching caused or amplified by voluntary movement or even the intention to move. This can be exacerbated by attempts at precise, coordinated movements. Active myoclonus is the most disabling form of myoclonus and can affect the arms, legs, face and even the voice. Often associated with tonic-clonic seizures and diffuse neuronal diseases such as posthypoxic encephalopathy, uremia, and various forms of PME, although in cases of focal cerebral damage the disease may be limited to one limb. This type of myoclonus is often caused by brain damage that occurs when there is a lack of oxygen and blood flow to the brain when breathing or heartbeat temporarily stops. Oversaturation of the sensorimotor cortex (cortical reflex myoclonus) or reticular formation (reticular reflex myoclonus) is also the cause of the action of myoclonus. Serotonin and GABA Neurotransmitters are thought to cause this lack of inhibition, which is a possible explanation for why improvements are achieved when serotonin precursors are administered. The systems involved include the cerebellodentatorubral, pyramidal, extrapyramidal, optic, auditory, posterior columns, as well as the gracile and cuneate nuclei, spinocerebellar tracts, motor neurons of the cranial nerves and anterior horns, and muscle fibers.[5]
• Palatal
  myoclonus is a regular, rhythmic contraction of one or both sides of the back of the mouth, called the soft palate. These contractions may be accompanied by myoclonus in other muscles, including the muscles of the face, tongue, throat, and diaphragm. The contractions are very rapid, occurring up to 150 times per minute, and can persist during sleep. The disease usually occurs in adults and can last indefinitely. People with palatal myoclonus usually consider it a minor problem; some complain of an intermittent “clicking” sound made when the soft muscles of the palate contract.
• Middle ear
  myoclonus occurs in the muscles of the middle ear. These muscles may include the tensor tympani and stirrup muscles. It may affect the muscles surrounding the eustachian tube, which include the tensor veli palatini, levator veli palatini, and salpingopharyngeus. Patients describe it as a knocking or sensation in the ear.
• Spinal
  myoclonus - myoclonus of the spinal cord, including segmental and propriospinal myoclonus. The latter usually occurs due to the thoracic generator producing a push when the trunk is flexed. It is often caused by a delayed stimulus due to slow conduction of propriospinal nerve fibers.[6]
• Stimulus-sensitive
  myoclonus is triggered by a variety of external events, including noise, movement, and light. Surprise may sensitize the patient.
• Sleep
  myoclonus occurs during the initial stages of sleep, especially as you fall asleep, and includes familiar examples of myoclonus such as hypnotic moron. Some forms appear to be sensitive to stimuli. Some people with sleep myoclonus rarely experience it or require treatment. If it is a symptom of a more complex and troubling sleep disorder, such as restless legs syndrome, treatment may be required. Myoclonus may be associated with patients with Tourette's syndrome.

general description

Myoclonus (benign hereditary essential myoclonus) (G25.3) is an inherited disorder, subcortical myoclonus, characterized by irregular arrhythmic and asynchronous jerks and winces with a multifocal and generalized distribution of myoclonus.
Myoclonus is a sudden muscle contraction that occurs when moving the limbs (usually the arms). Prevalence: 1 per 100 thousand people.

An autosomal dominant type of inheritance is characteristic.

Signs and symptoms

A myoclonic seizure can be described as "jumping" or "jumping" events experienced at one time. limb or even the whole body. The sensation experienced by the person is described as uncontrollable shaking, consistent with mild electric shock.[7] Sudden jerking and jerking of the body can often be so severe that it can cause a small child to fall.

Myoclonic seizure ( myo

“muscle”,
clonic
“jerk”) is a sudden involuntary contraction of muscle groups. Muscle tremors consist of symmetrical, in most cases generalized, localized in the arms and shoulders, and also simultaneously with a nod of the head; both hands may fly out together and a head nod may occur at the same time. Symptoms vary among subjects. Sometimes the whole body may twitch, as if in response to fear. As with all generalized seizures, the patient is not conscious during the event, but the seizure is so short that the person appears to remain fully conscious.

In reflex epilepsy-myoclonic seizures, they can be triggered by flashing lights or other environmental factors (see photosensitive epilepsy).

Familiar examples of normal myoclonus include: hiccups and hypnotic jerks that some people experience while falling asleep. Severe cases of pathological myoclonus can distort movement and severely limit a person's ability to sleep, eat, talk and walk. Myoclonic jerks usually occur in people with epilepsy.

Classification of myoclonus

The symptoms of myoclonus are very diverse. The above classification reflects the characteristics that are used to describe the clinical picture of any muscle contraction. The etiological factor and pathophysiological mechanisms underlying the occurrence of the exciting signal are also taken into account.

1. By the nature of muscle contractions:

• Synchronous and asynchronous contractions in muscles;
• Rhythmic and irregular twitching;
• Constant and episodic muscle contractions;
• Focal (local), multifocal (affect several muscles), segmental (part of the body is involved) and generalized (convulsive twitching of all muscles of the body).

1. By the nature of occurrence: spontaneous and reflex (appear in response to an irritating factor).
2. By etiology:

• Physiological;
• Essential;
• Epileptic;
• Symptomatic.

1. In relation to movement:

• Occurs during movement (action);
• They appear at the end of a movement (intentional).

Cause

Myoclonus in healthy people can only indicate voluntary muscle contraction. Myoclonus may also develop in response to infection, hyperosmolar hyperglycemic state, head or spinal cord injury, stroke, stress, brain tumors, kidney or liver failure, lipid storage disease, chemical or drug poisoning, as a side effect of certain medications (eg, tramadol,[8]quinolones, benzodiazepine, gabapentin, sertraline, lamotrigine, opioids) or other disorders.

Benign myoclonic movements are commonly observed during induction of general anesthesia with intravenous drugs such as etoidate and propofol. It is assumed that they arise as a result of a decrease in inhibitory signaling from cranial neurons. Prolonged oxygen starvation of the brain, hypoxia, can cause posthypoxic myoclonus. People suffering from benign fasciculation syndrome may often experience myoclonic jerking of the limbs, fingers and thumbs.

Myoclonus can occur on its own, but most often as one of several symptoms associated with various nervous system disorders, including multiple sclerosis, Parkinson's disease, Alzheimer's disease, opsoclonus myoclonus, Creutzfeldt-Jakob disease, Lyme disease, and lupus. Myoclonic jerks usually occur in people with epilepsy, a disease in which the electrical activity of the brain is disrupted, leading to seizures. It is also found in MERRF (Myoclonic Epilepsy with Ragged Red Fibers), a rare mitochondrial encephalomyopathy.

Twitching of muscle groups, a large part of the body, or a series in rapid succession that results in jerking of the bolt in an upright position from a more relaxed sitting position, is sometimes observed in outpatients receiving high doses of morphine, hydromorphone and similar drugs, possibly a sign of high and/or rapidly increasing serum levels of these drugs. Myoclonic seizures caused by other opioids such as tramadol and pethidine may be less favorable. Non-opioid medications such as anticholinergics are known to cause myoclonic seizures.[9]

Causes of myoclonus

In some cases, traumatic brain injury leads to the appearance of myoclonus.
There are many causes of myoclonus; the most common ones are listed below.

1. Traumatic brain injuries.
2. Past viral infections.
3. Hypoxic brain damage (oxygen starvation of the brain).
4. Intoxication (alcohol, drugs, toxic products).
5. Metabolic disorders (decreased blood concentrations of potassium, sodium, glucose).

The coordinated work between the cerebellum, reticular pharmacy and cerebral cortex is disrupted. The cerebellum loses the ability to regulate the stimulating effect of the cortex on the muscles, and excessive contraction occurs.

Pathophysiology

Most myoclonus is caused by a disorder of the central nervous system. Some of the peripheral nervous system injury, damage. Research shows that multiple areas of the brain are involved in myoclonus. One is located in the brain stem, near structures responsible for the startle response, an automatic response to an unexpected stimulus that involves rapid muscle contraction.[ citation needed

]

The specific mechanisms underlying myoclonus are not yet fully understood. Scientists believe that some types of stimulus-sensitive myoclonus may involve overexcitability of the parts of the brain that control movement. These parts are connected by a series of feedback loops called motor pathways. These pathways facilitate and modulate communication between the brain and muscles. The key elements of this communication are chemicals known as neurotransmitters, which carry messages from one nerve cell or neuron to another. Neurotransmitters are released by neurons and attach to receptors on parts of neighboring cells. Some neurotransmitters can make the receiving cell more sensitive, while others tend to make the receiving cell less sensitive. Laboratory studies suggest that an imbalance between these chemicals may underlie myoclonus.[ citation needed

]

Some researchers [ according to whom?

] suggest that abnormalities or deficiencies in receptors for certain neurotransmitters may contribute to some forms of myoclonus.
Receptors that appear to be associated with myoclonus include those for two important inhibitory neurotransmitters: serotonin, which constricts blood vessels and induces sleep, and gamma-aminobutyric acid (GABA), which helps the brain maintain muscle control.[citation needed ]
Others Receptors associated with myoclonus include receptors for benzodiazepines, drugs that induce sleep, and for glycine, an inhibitory neurotransmitter that is important in the control of motor and sensory functions of the spinal cord.[
citation needed
] More research is needed to determine how these receptor abnormalities cause or contribute to myoclonus.

treatment

For more serious diseases, the complex origins of myoclonus can be treated with several medications that have limited effect alone, but are more potent when combined with other drugs that act on other brain pathways or mechanisms. Treatment is most effective when the underlying cause is known and can be treated as such. Some drugs being studied in various combinations include: clonazepam, sodium valproate, piracetam, and primidone. Hormone therapy may improve response to antimyoclonic drugs in some people.

Some studies have shown that doses of 5-hydroxytryptophan (5-HTP) lead to improvement in patients with certain types of myoclonus and PME.[ citation needed

] These differences in the effects of 5-HTP in patients with myoclonus have not yet been explained.

Many drugs used for myoclonus, such as barbiturates, phenytoin, and primidone, are also used to treat epilepsy. Barbiturates slow down the central nervous system and cause a sedative or anticonvulsant effect. Phenytoin and primidone are effective antiepileptic drugs, although phenytoin may cause liver failure or have other harmful long-term effects in patients with PME. Sodium valproate is an alternative therapy for myoclonus and can be used alone or in combination with clonazepam. Some people have adverse reactions to clonazepam and/or sodium valproate.

When patients are taking multiple medications, stopping the medications that cause myoclonus and treating metabolic disorders may resolve some cases of myoclonus.[10] When pharmacological treatment is indicated, anticonvulsants are the mainstay of treatment. The paradoxical responses to treatment are remarkable. Medicines that most people respond to may make their symptoms worse in others. Sometimes this leads to the mistake of increasing the dose rather than decreasing or stopping the drug.[11] Treatment for myoclonus involves taking medications that can help reduce symptoms. Drugs used include sodium valproate, clonazepam, the anticonvulsant levetiracetam, and piracetam.[10] Dosages of clonazepam are usually increased gradually until the patient's condition improves or side effects become dangerous. Drowsiness and loss of coordination are common side effects. The beneficial effects of clonazepam may decrease over time if the patient develops tolerance to the drug.

For forms of myoclonus where only one area is affected, and even for several other different forms, Botox injections (OnabotulinumtoxinA) may be helpful. The chemical messenger responsible for triggering involuntary muscle contractions is blocked by the botulinum toxins in Botox.[12]

Surgery is also an acceptable treatment option if symptoms are caused by a tumor or lesion in the brain or spinal cord. Surgery can also correct symptoms in those whose myoclonus affects parts of the face or ear. Although DBS is still being studied for the treatment of myoclonus, deep brain stimulation has also been tried in people with this and other movement disorders.[13]

Clinical picture

The disease debuts at 10–20 years of age with nonrhythmic multifocal bilateral myoclonic twitching, involving the facial muscles, muscles of the neck, arms, and sometimes the trunk and legs. Myoclonus in different muscles occurs asynchronously, intensifies with active movements, emotions, can be suppressed by willpower, and disappears in sleep. Characterized by a decrease in muscle twitching when walking and distraction.

Manifestations of the disease can be combined with tremor and dystonia; as a rule, they do not progress. The severity of myoclonus decreases with alcohol intake and is poorly controlled with medications.

An objective examination of the patient reveals bilateral asynchronous nonrhythmic multifocal myoclonic twitching of the muscles of the face, neck, upper extremities, torso, and less commonly lower extremities. Myoclonic discharges - 10–50 per minute, amplitude - from single twitches to pronounced large-scale movements. In 30–40% of cases, mild signs of focal dystonia, postural tremor, and revitalized tendon reflexes are observed.

Forecast

The effects of myoclonus in a person can vary depending on the form and the person's overall health. In severe cases, especially those that indicate an underlying brain or nerve disorder, movement can be extremely distorted and limit the ability to function normally, such as eating, talking and walking. In these cases, normally effective treatments such as clonazepam and sodium valproate may instead cause an adverse drug reaction, including increased tolerability and a greater need for increased dosage. However, the prognosis for simpler forms of myoclonus in healthy people may be neutral, as the disease may cause little or no problems. In other cases, the disease begins simply in one part of the body and then spreads.[13]

Diagnosis of essential myoclonus

• Electroencephalography (absence of epileptiform activity).
• Electromyography (short bursts of spontaneous muscle activity lasting 50–100 ms, synchronous with myoclonus).
• CT/MRI of the brain (no organic pathology detected).

Differential diagnosis:

• Myoclonic epilepsy.
• Essential tremor.
• Myoclonus in storage diseases, spinocerebellar ataxias, degenerative diseases, viral encephalitis, metabolic and toxic encephalopathies.

Study

Myoclonus research is supported by the National Institute of Neurological Disorders and Stroke (NINDS). The research focuses on the role of neurotransmitters and receptors involved in the disease. Determining whether abnormalities in these pathways cause myoclonus may help develop drug treatments and diagnostic tests. Determining the extent to which genetics influence these abnormalities could lead to potential treatments to reverse them, potentially correcting the loss of inhibition while enhancing mechanisms in the body that compensate for their effects.[14]

Etymology

The word myoclonus

uses a combination of forms from
myo-
and
clonus
, which indicates dysfunction of muscle contraction.
Pronounced /ˌmaɪˈɒkləpəs/[15] or /ˌmaɪəˈkлoʊпəs,ˌmaɪoʊ-/[16]. The predominance of variants shows the division between American English and British English. The variant emphasizing -oc-
syllable is the only pronunciation given in half a dozen major American dictionaries (medical and general).
A variant emphasizing the -clo-
syllable is given in the online British English module of the Oxford Dictionaries[17] but not in the American English module.

Symptoms

References

1. Lava, Neil. "What is juvenile myoniclonic epilepsy." WebMD Medical Directory
   . Atlanta, GA: WebMD. Treatment of juvenile myoclonic epilepsy. Retrieved April 30, 2015.
2. ^ a b c d
   Patterson, Victoria (November 9, 2011).
   Belly Dancer Syndrome: Causes, Clinical Manifestations, and Treatment Options
   (PDF) (Senior Research Project). supported by Powers, E.J. Chesterfield, MO: Logan University. Retrieved September 1, 2015.
3. Thursday, February 23, 2012 (2012-02-23). "The Chaz Moore Story." Daily smoker. Retrieved 2014-02-28.
4. "CNN Medical Correspondent Apologizes for Questioning Medical Marijuana." Marijuanadoctors.com. Retrieved 2014-02-28.
5. Lance J. W. (1986). "Effect of myoclonus, Ramsay Hunt syndrome and other myoclonic syndromes of the cerebellum." Adv Neurol
   .
   43
   : 33–55. PMID 3080851.
6. Brown P, Thompson PD, Rothwell JC, Day BL, Marsden CD (1991). "Axial myoclonus of propriospinal origin." Brain
   .
   114
   : 197–214. Doi:10.1093/oxfordjournals.brain.a101857. PMID 1998882.
7. "Myoclonic seizures." DooseSyndrome.org
   . Doose Syndrome Epilepsy Alliance. Retrieved May 1, 2015.
8. https://databankws.lareb.nl/Downloads/kwb_2002_3_trama.pdf]
9. Ramnarine, Mityanand "Anticholinergic toxicity" emedicine.medscape.com, August 9, 2015.
10. ^ a b
    Van Zandijke, M. (June 2003).
    "Treatment of myoclonus." Acta Neurol Belg
    .
    103
    (2):66–70. PMID 12891998.
11. Andrade, D.M.; Hamani, C.; Minassian, B. (July 2009). "Treatment options for epileptic myoclonus and myoclonus-related epilepsy syndromes." Opin Pharmacother Expert
    .
    10
    (10): 1549–60. Doi:10.1517/14656560903025189. PMID 19527185. S2CID 207477900.
12. "Treatment of myoclonus and medications." MayoClinic.org. Mayo Clinic, n.d. Internet. May 01, 2015. https://www.mayoclinic.org/diseases-conditions/myoclonus/basics/treatment/con-20027364>
13. ^ a b
    "NINDS Myoclonus Information Page". Ninds.nih.gov. National Institute of Neurological Disorders and Stroke, n.d. Online. May 01, 2015. https://www.ninds.nih.gov/disorders/myoclonus/myoclonus.htm Archived 2016-12-06 in the Wayback Machine>.
14. "NINDS Myoclonus Information Page". Ninds.nih.gov. National Institute of Neurological Disorders and Stroke, n.d. [1] Archived 2016-12-06 in the Wayback Machine.
15. "Myoclonus." Merriam-Webster Dictionary
    .
16. "Myoclonus." Oxford Dictionaries British Dictionary
    . Oxford University Press. Retrieved 2016-01-20.
17. Oxford Dictionaries, Oxford Dictionaries Online
    , Oxford University Press.

Incidence (per 100,000 people)