• A disorder characterized by involuntary and irregular muscle contractions not associated with muscle weakness or atrophy. It most often affects facial muscles. It may be localized or generalized.
  NCI
  U.S. National Cancer Institute, 2021
• Myokymia consists of involuntary, fine, continuous, undulating contractions that spread across the affected striated muscle.
  Human Phenotype Ontology (HPO)
  The Human Phenotype Ontology Project, 2025
• Successive and rapid contractions of motor units associated with chronic nerve injury. The discharges arise from the peripheral aspects of regenerating nerves, and clinically impart a nearly continuous undulation of the body surface overlying the muscle. (Adams et al., Principles of Neurology, 6th ed, p1491)
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• Myokymia, a form of involuntary muscular movement, usually can be visualized on the skin as vermicular or continuous rippling movements. The word myokymia was used first more than 100 years ago, when Schultze described continuous, slow, undulating muscular contractions in small muscles of hands and feet.
  Medscape
  WebMD, 2025
• Morvan syndrome is a rare, life-threatening, acquired neurologic disease characterized by neuromyotonia, dysautonomia and encephalopathy with severe insomnia. Signs involving central (e.g. hallucinations, confusion, amnesia, myoclonus), autonomic (e.g. variations in blood pressure, hyperhidrosis) and peripheral (e.g. painful cramps,...
  NIH Genetic and Rare Diseases
  National Center for Advancing Translational Sciences