[Management of muscle cramp: what's to be done?]

Muscle cramp is characterized by involuntary, painful, visible contraction of a muscle (or a part of muscle) and is always associated with irregular repetitive firing of motor unit action potentials (200 à 300 Hz) which is caused by hyperexcitability of intramuscular terminal motor axons. It's a common condition in normal people, but most commonly in young people (pregnancy, exercise) and more in the elderly (50% after 65 years-old). A careful history and examination should allow the physician to determine the significance of cramp. ENMG and biological tests are needed in cases of severe symptoms (severity and frequency of cramps) and/or abnormal examination. Idiopathic and secondary (drug or metabolic disorders) cramps are the most common groups, but it's very important to search the motor unit diseases (neuropathy, radiculopathy, plexopathy, neuromyotonia, and a cramp fasciculation syndrome which can preceded ALS). The first goal in management of cramp is to determine if there is an underlying cause and the second to use physical measures (stretching), because, pharmacologic treatments have a moderate interest because of the potential of toxicity (quinine sulfate) or a little effectiveness (vitamin B complex, naftidrofuryl, and calcium channel blockers such as diltiazem, gabapentin). Isolated cramp doesn't need treatment.