Myoclonus

Myoclonus is a condition whereby a muscle or muscle group cramps and contracts quickly and briefly. This myoclonus phenomenon is similar to a sudden muscle cramp but begins and ends more rapidly. Myoclonus is both a symptom and a disease. Myoclonus may only involve one muscle, one group of muscles in the hand, or a group of muscles in the extremities.

Myoclonus may occur in absence of a medical disorder, like when a person is falling asleep or gets a case of the hiccups. Hiccups are a type of myoclonus that involves only the diaphragm, the muscle that separates the chest and the stomach. These symptoms of myoclonus occur in healthy individuals and do not usually bring people to the doctor.

As a disease, myoclonus is the result of some damage to the central nervous system which causes the nerves to fire and cause an involuntary muscle contraction. Virtually all types of brain and spinal cord injuries and illnesses can cause myoclonus. In other cases, myoclonus is the result of a disease like kidney or liver failure. Myoclonus can occur after cardiac arrest or in response to a drug overdose of levodopa, bismuth, or other drugs. Myoclonus can also occur in some seizure disorders, such as progressive myoclonic epilepsy and certain types of degenerative disorders, like Alzheimer’s disease.

In some patients, myoclonus can be mild, while in many patients the disease can cause significant disability. This movement disorder impedes on normal posture and muscle movements. In more serious cases, myoclonus can cause strong uncontrollable contractions in part or all of the body. During these episodes, a person is often unable to carry out voluntary motor tasks. Patients with severe myoclonus may be unable to walk, grab objects, dress, speak, or even be able to focus. Myoclonus episodes are usually triggered by movement.

While there is no known cure for myoclonus, some patients benefit from the use of medications. Anticonvulsants, such as clonazepam and valproate, are considered the most effective treatments for myoclonus. Often these medications are used in conjunction with their drugs to effectively relieve a patient’s symptoms. These drugs can include primidone, piracetam and acetazolamide. All of the drugs used to treat myoclonus are associated with side effects that patients should be sure to discuss with their doctor before beginning treatment.