Introduction
Myoclonus is an uncontrollable jerking movement. It is frequently sudden and brief. It is caused by the disturbance of the CNS (central nervous system), the brain, or the spinal cord, while many causes can be normal and do not cause any harm.
What Is Myoclonus?
Myoclonus is a quick, often brief muscle jerking, twitching, or spasm-like movement. It is caused when the muscles inappropriately get activated and frequently last for a fraction of a second. A single muscle or a group of them can get affected in myoclonus. Some reasons more likely affect the muscles in the hands or feet, shoulders or hips, back or face. Myoclonus can be seen in people who are healthy at some point. However, it is also a possible symptom of various medical conditions, some of which are serious. The two main ways in which myoclonus happens are:
-
Positive Myoclonus: This condition occurs when the muscles are contracted or flexed suddenly.
-
Negative Myoclonus: This condition is seen when the muscles are relaxed suddenly (also called asterixis, often described as a hand-flapping tremor).
What Are the Causes of Myoclonus?
Myoclonus can occur due to various reasons. Some of the reasons are considered normal and are expected. Others occur due to specific conditions and disorders that affect various systems in the body. Myoclonus is divided into the following main categories:
Normal Forms of Myoclonus:
Various processes in the body can cause myoclonus to occur for normal reasons. These are called examples of physiological myoclonus by experts. Some of their types are:
-
Hiccups (these are normal unless they continue for a couple of days or more).
-
Sleep myoclonus (also known as hypnic jerks, are the sudden sharp muscle movements that occur as a person falls asleep or wakes up).
-
Startle reflexes (a jump-like movement that cannot be controlled when someone is surprised or scared).
Epileptic Myoclonus:
Myoclonus can happen with or because of seizures (especially myoclonic seizures). This includes seizures due to different forms of epilepsy, such as Lennox-Gastaut syndrome or juvenile myoclonic epilepsy.
Secondary Myoclonus:
When myoclonus occurs as a symptom of another condition, it is known as secondary myoclonus. Secondary myoclonus can occur due to a wide variety of reasons. Some of these only affect the brain or other areas of the nervous system. Others might affect many systems of the entire body. The common causes of secondary myoclonus are:
-
Autoimmune Diseases: These are the conditions in which the immune system attacks the body itself, for example, in celiac disease.
-
Blood and Body Chemistry Imbalances: These can occur along with kidney or liver diseases and conditions affecting the thyroid. It can also be seen due to vitamin or mineral deficiencies and electrolyte imbalances.
-
Brain Lesions: These are the damaged portions of brain tissue. The damage disrupts the working of these areas, which results in myoclonus. Examples include damage due to lack of oxygen (cerebral hypoxia) or reduced blood flow because of a stroke.
-
Degenerative Brain Diseases: Examples of these diseases are Alzheimer’s disease, Lewy body dementia, etc. It can also occur along with Parkinson’s disease-related dementia.
-
Genetic Disorders: These conditions occur due to mutations in DNA (deoxyribonucleic acid), including mutations that can be acquired from the parents. Examples are Krabbe disease and Wilson disease.
-
Infections: Frequently seen infections are viral or bacterial infections that attack the brain or other parts of the nervous system, for example, herpes simplex virus or Lyme disease.
-
Nerve and Spinal Cord Injuries: Damage to the spinal cord or nerves can interfere with the normal communication of the brain with other parts of the body. Without proper communication, body parts might act spontaneously, causing myoclonus.
-
Non-medical Drugs and Substances: These substances include alcohol, amphetamines, cocaine, ecstasy, heroin, etc. Inhalants like toluene and gasoline can also result in myoclonus.
-
Prescribed Medications: Various medications can result in myoclonus, such as anti-seizure medications, antidepressants, blood pressure medications, antibiotics, opioid painkillers, anesthetics, etc.
-
Poisons and Toxins: Poisoning due to heavy metals, such as lead, manganese, and mercury, can result in myoclonus. It can also be caused by certain other toxins, such as insecticides like methyl bromide.
Essential Myoclonus:
Essential myoclonus is a condition that is frequently seen running in families. This is an acquired type of myoclonus that is not harmful and frequently does not worsen with time. However, muscle movements might become more noticeable after consuming alcohol.
How Is Myoclonus Diagnosed?
Various tests can be done to identify and diagnose the reason for myoclonus. After the physical examination, a doctor also might advise some of the following tests:
-
Electroencephalography (EEG): It is done to record the electrical activity of the brain.
-
MRI (Magnetic Resonance Imaging) Or CT (Computed Tomography): These scans identify whether structural problems or tumors are present.
-
Electromyogram (EMG): This is done to evaluate the electrical impulses in muscles to check for the pattern of myoclonus.
-
Laboratory Tests: These are done to check for the presence of conditions that might be adding up to myoclonus, such as diabetes mellitus, metabolic disorders, autoimmune disease, kidney or liver disease, drugs, or toxins.
How Is Myoclonus Treated?
Generally, myoclonus does not require treatment if it exists in normal forms. The treatment for other types of myoclonus can differ widely. The treatment depends on the underlying cause, the medical history, the severity of the disease, etc. As the treatments vary, a doctor can advise either a sedative (tranquilizer) or anticonvulsant medication to help reduce spasms, surgery if required, or any alternative therapy depending on the symptoms.
How Is Myoclonus Prevented?
Myoclonus occurs too quickly and often without giving a signal. Some of them, such as the usual form of myoclonus, are not preventable. However, some secondary myoclonus can be prevented. One can control the way epileptic myoclonus occurs or how severe it is. It can be prevented by protecting the brain from any injury.
Conclusion
Myoclonus is a sudden or quick, wide series of movements like jerking experienced randomly. This is caused when the CNS is affected, resulting in spasms, uncontrollable movements, jerks, etc. It can be diagnosed with the help of an MRI, CT scan, etc. Its symptoms can be reduced by prescribing medications like sedatives, surgery, or therapies as per the type of myoclonus.
