Rate of diaphragmatic contraction ranges between 35 and 480 contractions per minute, with the average rate found to be 150.: 3  Studies show that possible causes include disruptions within the central or peripheral nervous systems, anxiety, nutritional disorder, and certain pharmaceuticals. No single treatment has proven effective, though blocking or crushing of the phrenic nerve can provide instantaneous relief when pharmacologic treatment has proven ineffective. : 11 Only about 50 people in the world have been diagnosed with diaphragmatic flutter. Other forms
Action myoclonus is characterized by muscular jerking triggered or intensified by voluntary movement or even the intention to move. It may be made worse by attempts at precise, coordinated movements. Action myoclonus is the most disabling form of myoclonus and can affect the arms, legs, face, and even the voice. It is often associated with tonic-clonic seizures and diffuse neuronal disease such as post-hypoxic encephalopathy, uremia, and the various forms of PME, although, in the case of focal cerebral damage, the disease may be restricted to one limb. This type of myoclonus often is caused by brain damage that results from a lack of oxygen and blood flow to the brain when breathing or heartbeat is temporarily stopped. Over-excitement of the sensorimotor cortex (cortical reflex myoclonus) or reticular formation (reticular reflex myoclonus) is also a cause of action myoclonus. Serotonin and GABA neurotransmitters are thought to cause this lack of inhibition, which is a possible explanation as to why improvements are made with the administration of serotonin precursors.
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  or . 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. See also
Periodic limb movement disorder
Benign fasciculation syndrome
Restless legs syndrome
Fasciculation
Brain Zaps (SSRI withdrawal)
Clonus
Fahrs syndrome

References
External links

The first version of this article was adapted from the public domain NINDS Myoclonus Information Page. "Why do we twitch while falling asleep?" (The Straight Dope)
Myoclonus Fact Sheet,  National Institute of Neurological Disorders and Stroke (viewed 5 Apr 2005)