myoclonus is caused by a disturbance of the central nervous system. some are from peripheral nervous system injury. studies suggest several locations in the brain are involved in myoclonus. one is in the brainstem, close to structures that are responsible for the startle response, an automatic reaction to an unexpected stimulus involving rapid muscle contraction. 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 interconnected in a series of feedback loops called motor pathways. these pathways facilitate and modulate communication between the brain and muscles. 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 themselves to receptors on parts of neighboring cells. some neurotransmitters may 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. some researchers speculate that abnormalities or deficiencies in the receptors for certain neurotransmitters may contribute to some forms of myoclonus. receptors that appear to be related to myoclonus include those for two important inhibitory neurotransmitters: serotonin, which constricts blood vessels and brings on sleep, and gamma-aminobutyric acid (gaba), which helps the brain maintain muscle control. other receptors with links to myoclonus include those for benzodiazepines, drugs that induce sleep, and for glycine, an inhibitory neurotransmitter that is important for the control of motor and sensory functions in the spinal cord. more research is needed to determine how these receptor abnormalities cause or contribute to myoclonus. treatment concerning more serious conditions, the complex origins of myoclonus may be treated with multiple drugs, which have a limited effect individually, but greater when combined with others that act on different 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 different combinations include clonazepam, sodium valproate, piracetam, and primidone. hormonal therapy may improve responses to antimyoclonic drugs in some people. some studies have shown that doses of 5-hydroxytryptophan (5-htp) leads to improvement in patients with some types of action myoclonus and pme. these differences in the effect of 5-htp on patients with myoclonus have not yet been explained. many of the 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 tranquilizing or antiseizure effects. phenytoin and primidone are effective antiepileptics drugs, although phenytoin can 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 either alone or in combination with clonazepam. some people have adverse reactions to clonazepam and/or sodium valproate. when patients are taking multiple medications, the discontinuation of drugs suspected of causing myoclonus and treatment of metabolic derangements may resolve some cases of myoclonus. when pharmacological treatment is indicated anticonvulsants are the main line of treatment. paradoxical reactions to treatment are notable. drugs which most people respond to may in other individuals worsen their symptoms. sometimes this leads to the mistake of increasing the dose, rather than decreasing or stopping the drug. treatment of myoclonus focuses on medications that may help reduce symptoms. drugs used include sodium valproate, clonazepam, the anticonvulsant levetiracetam, and piracetam. dosages of clonazepam usually are increased gradually until the patient improves or side effects become harmful. drowsiness and loss of coordination are common side effects. the beneficial effects of clonazepam may diminish over time if the patient develops a tolerance to the drug. in forms of myoclonus where only a single area is affected, and even in a few other various forms, botox injections (onabotulinumtoxina) may be helpful. the chemical messenger responsible for triggering the involuntary muscle contractions is blocked by the botulinum toxins of the botox. surgery is also a viable option for treatment if the symptoms are caused by a tumor or lesion in the brain or spinal cord. surgery may also correct symptoms in those where myoclonus affects parts of the face or ear. while dbs is still being studied for use with myoclonus, deep brain stimulation has also been tried in those with this and other movement disorders. prognosis the effects of myoclonus in an individual can vary depending on the form and the overall health of the individual. in severe cases, particularly those indicating an underlying disorder in the brain or nerves, movement can be extremely distorted and limit ability to normally function, such as in eating, talking, and walking. in these cases, treatment that is usually effective, such as clonazepam and sodium valproate, may instead cause adverse reaction to the drug, including increased tolerance and a greater need for increase in dosage. however, the prognosis for more simple forms of myoclonus in otherwise healthy individuals may be neutral, as the disease may cause few to no difficulties. other times the disease starts simply, in one region of the body, and then spreads. research research on myoclonus is supported through the national institute of neurological disorders and stroke (ninds). the primary focus of research is on the role of neurotransmitters and receptors involved in the disease. identifying whether or not abnormalities in these pathways cause myoclonus may help in efforts to develop drug treatments and diagnostic tests. determining the extent that genetics play in these abnormalities may lead to potential treatments for their reversal, potentially correcting the loss of inhibition while enhancing mechanisms in the body that would compensate for their effects. etymology the word myoclonus uses combining forms of myo- and clonus, indicating muscle contraction dysfunction. it is pronounced /ˌmaɪˈɒklənəs/ or /ˌmaɪəˈkloʊnəs, ˌmaɪoʊ-/. the prevalence of the variants shows division between american english and british english. the variant stressing the -oc- syllable is the only pronunciation given in a half dozen major american dictionaries (medical and general). the variant stressing the -clo- syllable is given in the british english module of oxford dictionaries online but not in the american english module.