Muscle twitching

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Deep anterior muscles

Muscle twitches are fine movements of a small area of muscle.

Muscle fasciculation; Fasciculations of muscle

Muscle twitching is caused by minor muscle contractions in the area, or uncontrollable twitching of a muscle group that is served by a single motor nerve fiber.

Muscle twitches are minor and often go unnoticed. Some are common and normal. Others are signs of a nervous system disorder.

• Diet deficiency
• Drug overdose (caffeine)
• Drug side effect (such as from diuretics, corticosteroids, or estrogens)
• Exercise
• Twitches not caused by disease or disorders (benign twitches)
  • Often affecting the eyelids, calf, or thumb
  • Normal and quite common, often triggered by stress or anxiety
  • Come and go, and do not last for more than a few days

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Nervous system conditions that can cause muscle twitching:

• Amyotrophic lateral sclerosis (ALS - Lou Gehrig's disease)
• Damage to the nerve that leads to a muscle
• Muscular dystrophy
• Spinal muscular atrophy
• Weak muscles (myopathy)

Symptoms that suggest a nervous system disorder include:

• Loss of, or change in sensation
• Loss of muscle size (wasting)
• Weakness

Review Date: 03/21/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Luc Jasmin, MD, PhD, Department of Neurosurgery at Cedars-Sinai Medical Center, Los Angeles, and Department of Anatomy at UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).