Muscle twitches and cramps

What are the common causes of muscle twitches and cramps?

Muscle twitching and cramps are common normal symptoms, occasionally they may indicate an underlying neurological condition but are nearly always benign. In one study over 50% of the population had muscle fasciculation and 37% of had muscle cramps in a single year.

• Muscle fasciculation. Usually seen or felt, most commonly in the calves and after exercise but may be more widespread. They can be associated with cramps and in the absence of weakness are usually “benign cramp/fasciculation syndrome”. Nearly always benign. Health-related anxiety (MND specifically) can amplify them.
• Myokymia: painless repetitive muscle fibre twitching, commonly seen around the eye or first dorsal interosseous muscle. Nearly always benign.
• Myotonia: described by patients as “muscle stiffness” or discomfort rather than visible twitching with an inability to relax a muscle. It’s rare and suggests underlying neuromuscular disease (e.g. myotonic dystrophy or neuromyotonia).
• Muscle cramps: the sudden involuntary painful contraction of an isolated muscle cramp is usually benign and commonly worsened by exercise, dehydration, or pregnancy, and especially sleep in the elderly (sleeping with feet plantarflexed). Occasionally, when profound and/or associated with other symptoms such as weakness, they may indicate underlying neuromuscular disease. Metabolic disorders may also cause cramp.
• Blepharospasm: This is bilateral repeated eye closure (blinking) due to overactivity of the orbicularis oculi muscle. Benign, if annoying and cosmetically embarrassing, and can cause effective blindness in more severe cases.
• Hemifacial spasm: what it says on the tin- unilateral eye blinking with upwards twitching of the corner of the mouth.