Myoclonus is a condition involving rapid involuntary twitching of a muscle or group of muscles. Myoclonus may be a primary condition, meaning that it is not a symptom of another medical condition, or a secondary symptom of other conditions such as Alzheimer’s disease, seizures, brain disorders or neuromuscular disorders. Myoclonus may be mild or be so intense that it interferes with normal routines or sleep. Treatment focuses on relieving the symptoms, so patients are often prescribed tranquilzers, anticonvulsants, muscle relaxants, botox, and in more rare cases in children, immunosuppressants.
Tranquilizers
Tranquilizers (specifically benzodiazepines) are the primary treatment for symptoms of myoclonus, according to the Medical College of Wisconsin. Benzodiazepines, including diazepam, lorazepam, alprazolam and chlordiazepoxide, are tranquilizers that work by affecting the brain’s cortex region, the brain stem and the spinal cord. These medications affect emotions, reduce convulsions and reduce muscle spasms, which is the beneficial effect for myoclonus.
Because benzodiazepines depress the central nervous system, there are side effects associated with their use. The most common side effects include confusion, slurred speech, lack of coordination, dizziness, headache and nausea.
Anticonvulsants
Medications that are used to control epileptic seizures, known as anticonvulsants, may also be used to treat myoclonus. The most commonly prescribed drugs from this group, according to the doctors at the Mayo Clinic, are divalproex sodium, primidone and levetiracetam.
Divalproex sodium can trigger gastrointestinal side effects including nausea, vomiting and indigestion. Other side effects include headache, seeing spots (a condition called asterixis), dizziness, loss of coordination, muscle weakness, thrombocytopenia (low blood platelet count), depression and liver problems. Primidone is known to cause unsteadiness, trembling, loss of muscle coordination, dizziness and a spinning sensation, while levetiracetam causes similar side effects of dizziness, drowsiness, irritability and weakness.
Muscle Relaxants
Dantrolene relaxes muscles by interfering with the release of calcium from the cells in the muscles. Patients taking calcium-channel blocker medications should take caution when using dantrolene, as it can result in life-threatening myocardial depression or hyperkalemia (elevated potassium levels). Dantrolene may also result in muscle weakness.
Immunosuppressants
Immunosuppressants are effective in treating some special forms of myoclonus, such as opsoclonus-myoclonus, in children. Because these conditions are caused by the actions of anti-neuronal antibodies and inflammation in the brain, treatment often includes adrenocorticotropic hormone (ACTH), azathioprine, corticosteroids and immunoglobulin therapy.
The side effects of corticosteroids may include a change in appetite, nervousness, restlessness, sleep interruptions and indigestion, and azathioprine may cause cough, chills, fever and unusual tiredness. ACTH therapy may cause irritability, weight gain, high blood pressure and an increase in blood sugar levels. Immunoglobulin therapy rarely causes side effects, but if they do occur, may include headache, myalgia, fever, chills, lower back pain, nausea or vomiting.
Botox Injections
Botox (botulinum toxin type A) injections may also help to relieve myoclonus by inhibiting the release of certain chemicals from the muscles that trigger muscle contractions. Botox does not usually cause side effects, but some patients have experienced dizziness, headache, drowsiness, dry mouth, sensitivity to light and anxiety. Because botox is injected locally into the affected muscle, it is only a useful treatment for those with myoclonus in a single area, according to the doctors at The Mayo Clinic.
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