What Is It, Causes, Signs and Symptoms, and More
Author:Anna Hernández, MD
Editors:Alyssa Haag,Ian Mannarino, MD, MBA,Kelsey LaFayette, DNP, ARNP, FNP-C
Illustrator:Jessica Reynolds, MS
Copyeditor:Stacy L. Johnson, LMSW
What is myokymia?
Myokymia describes involuntary muscle movement that can be seen on the skin, sometimes described as wormlike or continuous rippling movements. Myokymia may occur physiologically in healthy individuals or the form of facial or limb myokymia. Muscle spasms of the eyelid, particularly the lower eyelid, may be used to describe the twitching of other muscles.
What causes myokymia?
Myokymia is caused by the hyperactivation of one or more motor units, which are the functional units that control muscle contraction. A motor unit consists of a single motor neuron and the group of skeletal muscle fibers it innervates. Since each motor unit innervates several hundred muscle fibers, its activation causes a continuous rippling movement of the skin overlying the contracting muscle cells.
Eyelid myokymia, which may present as eyelid twitching, is common among healthy individuals and is usually triggered by stress, fatigue, lack of sleep, or caffeine. When myokymia occurs in the face, it most frequently affects the orbicularis oculi muscle, which is the muscle responsible for closing the eyelids. Less common causes of facial myokymia include damage to the facial nerve nucleus in the brainstem due to demyelinating disorders, such as multiple sclerosis or compression from brainstem tumors.
Limb or generalized myokymia, on the other hand, limb or generalized myokymia, are almost always a result of an underlying disorder affecting motor nerve function. Cervical or lumbar radiculopathies can cause limb myokymia; chronic entrapment of a nerve (e.g., median neuropathy at the carpal tunnel); or as a classic complication of radiation-induced nerve damage. Finally, generalized myokymia can be seen in acute inflammatory myopathies or neuropathies, such as Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy (e.g., multiple sclerosis), as well as in uremia, thyrotoxicosis, hereditary episodic ataxia, or due to timber rattlesnake venom. Although rare, generalized or limb myokymia may be seen after strenuous exercise in healthy individuals.
What are the signs and symptoms of myokymia?
The main symptom of myokymia is fine, quivering, rippling, and undulating muscle contractions that spread through the affected muscle. Eyelid myokymia is considered a benign, self-limiting process that tends to be unilateral and intermittent, with the lower eyelid affected more than the upper lid. Because the eyelids are so thin, eyelid myokymia has the appearance of an eyelid spasm or eye twitching rather than the undulating skin movements common to facial or limb myokymia. Episodes of eyelid myokymia are transient, lasting anywhere from a few days to a few weeks or months, with muscle spasms occurring intermittently throughout the day for up to several hours at a time. Occasionally, the muscle spasms may continue for several days or weeks.
How is myokymia diagnosed?
Diagnosis of myokymia is based on the medical history and physical exam. Diagnosis generally does not require additional tests in individuals with self-limited eyelid myokymia with no other accompanying symptoms. Differential diagnosis includes other causes of facial and eye spasms, including benign essential blepharospasm (i.e., involuntary muscle spasms that cause the eye to close partially or entirely) and hemifacial spasm (i.e., spasms in the muscles controlling facial expressions).
On the other hand, in cases where myokymia is persistent or an underlying cause is suspected, diagnosis involves performing electromyography (EMG). This test uses electrical stimuli to assess muscle function. If myokymia is confirmed on an EMG, diagnosis may involve additional tests to identify the underlying cause, including the brain's magnetic resonance imaging (MRI).
How is myokymia treated?
Generalized and limb myokymia treatment addresses the underlying cause when possible. In cases of eyelid myokymia, treatment begins by addressing any precipitating factors, such as managing stress, developing better sleep habits, decreasing screen exposure, and decreasing caffeine intake. In addition, applying a warm compress to the affected area may help relieve and relax muscle tension. If eyelid myokymia persists and significantly affects the individual’s quality of life, botulinum toxin injections may be used to paralyze the muscles that cause eyelid twitching.
What are the most important facts to know about myokymia?
Myokymia is the continuous undulation of a group of muscle fibers caused by the spontaneous activation of motor units. Myokymia may occur physiologically in healthy individuals, typically in the form of eyelid twitching, or be caused by an underlying disorder, including multiple sclerosis (MS), Guillain-Barré syndrome (GBS), and certain inflammatory myopathies and neuropathies. Diagnosis generally involves performing electromyography (EMG) to distinguish myokymia from other forms of involuntary muscle contraction and additional tests to identify the underlying cause. When possible, treatment of generalized or limb myokymia focuses on addressing the underlying cause. Eyelid myokymia may be treated by correcting any precipitating factors and applying warm compresses and botulinum toxin injections in refractory cases.
Quiz yourself on Myokymia
9 Questions availableQuiz now!
Watch related videos:
Related linksMuscles of the face and scalp
Neuromuscular junction and motor unit
Resources for research and reference
Gervasio, K. A., Moster, M. L., & Philadelphia, M. D. (2020, March 7). Managing eyelid and facial spasms. https://www.reviewofophthalmology.com/article/managing-eyelid-and-facial-spasms
Jafer Chardoub AA, Patel BC. Eyelid Myokymia. [Updated 2021 Nov 2]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560595/
Palasí, A., Martínez-Sánchez, N., Bau, L., & Campdelacreu, J. (2013). Unilateral eyelid myokymia as a form of presentation of multiple sclerosis. Neurología (English Edition), 28(3), 187–189. doi:10.1016/j.nrleng.2011.09.009
Zimnowodzki, S. (2010). Myokymia. Encyclopedia of Movement Disorders, 252–253. doi:10.1016/b978-0-12-374105-9.00355-5