Muscle cramps are usually involuntary, painful contractions of individual muscle groups (mostly calf muscles) and are usually caused by overuse of the muscles or disturbance of their electrolyte balance. Thus, a deficiency of magnesium or even other electrolytes (minerals) can trigger localized muscle cramps. Some individuals have a particular tendency to muscle cramps. Those people often have benign muscle twitching in the calves. Sometimes restless legs and muscle cramps can also occur in polyneuropathy, amyotrophic lateral sclerosis (ALS) or restless legs syndrome. Muscle cramps must be distinguished from seizures, which occur in the context of epilepsy. On the other hand, muscle cramps can also occur in certain movement disorders (e.g. dystonia, Parkinson’s disease, etc.). Muscle spasms causing waking from sleep are common and are categorized as sleep-related movement disorders. Muscle spasms can also occur in the chronic stage after a stroke or in paraplegia. The cause is usually associated with leg stiffness.
