Myoclonus is a quick, jerky, involuntary muscle movement. It occurs as a symptom of certain conditions. For example, hiccups or sleep starts (the sudden jerks which occur before falling asleep) are different forms of myoclonus. Myoclonus is a common phenomenon. However, if these jerky movements occur more frequently or involve several parts of the body, they can affect certain daily activities such as eating, talking or walking.
Myoclonus is of the following types:
- Essential myoclonus does not have any underlying cause. This condition does not change over a period.
- Action myoclonus occurs when the person moves or tries to move. This type can involve arms, legs, throat and face and is highly disabling.
- Opsoclonus myoclonus which includes the spasms or irregular movements of the eyes. It is common in children with viral eye infections or tumors. Additionally, there can be trouble speaking or irritability or lethargy.
- Stimulus sensitive myoclonus which is triggered by stimuli such as light, noise, etc.
- Physiological myoclonus is not associated with any illness and does not usually need treatment. For example hiccups, sleep starts, etc.
- Epileptic myoclonus occurs in patients with epilepsy.
- Symptomatic myoclonus results from an underlying condition.
Usually, these jerky movements are:
- Localized to a body part or may include the entire body
If the symptoms of myoclonus occur more frequently and persist for a long time then consult the doctor. The doctor evaluates the condition thoroughly and provides appropriate treatment.
Myoclonus occurs due to the unusual muscle contractions in response to the abnormal electrical impulses sent to the muscles from the brain. Several underlying conditions can produce myoclonus as a symptom. These include:
- Brain tumors
- Head or spinal cord injury
- Nervous system problems such as Parkinson’s disease, Huntington’s disease
- Kidney or liver failure
- Genetic disorders
- Hypoxia (long-periods of oxygen deficit)
- Chemical or drug poisoning
The doctor may ask for the patient’s medical history. He may also check for the signs of the condition. Further evaluation includes a physical examination. To exclude other possible causes, the doctor may order for one or more of the following tests:
- Electromyogram (EMG) to measure the electrical activity of the muscles
- Electroencephalogram (EEG) to determine the electrical activity of the brain
- Imaging tests such as an MRI, CT scan, SPECT or PET scan to check if there are any structural defects inside the brain or spinal cord
- Genetic testing may be required to know if there are any associated abnormal genes
- Additionally, certain blood and urine tests may be required to check for diabetes, kidney or liver disease, autoimmune disorders, drugs or toxic substances
Myoclonus associated with reversible underlying causes such as a medical condition, toxic substances or medications can be treated easily. However, in most of the cases, the underlying cause can’t be removed and the treatment can only improve the symptoms. Multiple drugs are given to control the symptoms of myoclonus:
- Medications such as tranquilizers are given to calm down the muscles. However, they can cause side effects such as drowsiness or loss of coordination.
- Anticonvulsant drugs are given to control seizures and certain other symptoms. Side effects of these drugs include dizziness, sedation and fatigue.
- Botulinum toxin injections are effective in treating several forms of myoclonus. They act by inhibiting the release of the chemical messengers which can trigger muscle contraction.
If myoclonus is due to conditions such as tumors or lesions in the brain or spinal cord, then the doctor might recommend surgery. Also, surgery is helpful in patients with myoclonus affecting the face and ears. The most common surgical method is deep brain stimulation (DBS). In this method, electrodes are implanted into the brain to produce the necessary impulses.
Additionally, the doctor will recommend certain behavioral changes to reduce the risk of developing certain symptoms. These may include, maintaining a large distance from the video monitors while making sure of the brightness of the backlight. This can benefit people who may have seizures associated with photosensitivity.