eMedicine Specialties > Neurology > Electromyography and Nerve Conduction Studies

Myokymia: Differential Diagnoses & Workup

Author: Suying Song, MD, Assistant Professor, Department of Neurology, New York University School of Medicine
Contributor Information and Disclosures

Updated: Oct 6, 2009

Differential Diagnoses

Amyotrophic Lateral Sclerosis
Striatonigral Degeneration
Epilepsia Partialis Continua
Tardive Dyskinesia
Hemifacial Spasm
Schwartz-Jampel Syndrome
Stiff Person Syndrome

Other Problems to Be Considered

Blepharospasm
Facial myoclonus
McArdle disease
Meige syndrome
Myotonic diseases
Spasticity
Tetanus

Workup

Laboratory Studies

Complete blood count, chemistry, creatine kinase, thyroid testing group, sedimentation rate, Lyme titer, Venereal Disease Research Laboratory (VDRL) test, and rheumatology screening are the basic laboratory tests for all patients with clinical myokymia. Serum alcohol level and toxic screen are recommended for acute onset of generalized myokymia.

Imaging Studies

Neuroimaging studies with CT scan or MRI usually are performed for certain regions after careful examination and in cases in which electrodiagnostic studies have localized a lesion to a particular area. For example, if facial myokymia is confirmed, MRI study of the brain with special attention to posterior fossa is ordered to search for an anatomic lesion. Imaging studies are not otherwise necessary for establishing the diagnosis of myokymia.

Other Tests

Nerve conduction velocity (NCV) and EMG studies are necessary to qualify and quantify neurogenic/myogenic dysfunction.

  • NCV can detect the presence of plexopathy, mononeuropathy, and polyneuropathy (axonal or demyelinating).
  • EMG can confirm the presence of myokymic discharges or neuromyotonia. The specific findings of myokymia in EMG examination are detailed in the Physical section.
  • EMG study also can document the presence of neurogenic/myogenic dysfunction and its distribution.
  • Information obtained through these studies serves as a guide for further diagnostic investigation. Serial studies can objectively document the evolution of the myokymia.

Procedures

Lumbar puncture with examination of cerebrospinal fluid (CSF) usually is performed for patients with documented acute or chronic polyradiculoneuropathy, central nervous system demyelinating disorder, or other suspected inflammatory, infectious, or neoplastic processes.

More on Myokymia

Overview: Myokymia
Differential Diagnoses & Workup: Myokymia
Treatment & Medication: Myokymia
Follow-up: Myokymia
References
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References

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Further Reading

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Keywords

myokymia, myoclonus fibrillaris multiplex, myokymic discharges, neuromyotonia, Isaacs syndrome, involuntary muscular movement, facial myokymia, focal myokymia, segmental myokymia, generalized myokymia

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Contributor Information and Disclosures

Author

Suying Song, MD, Assistant Professor, Department of Neurology, New York University School of Medicine
Suying Song, MD is a member of the following medical societies: American Academy of Neurology and American Association of Neuromuscular and Electrodiagnostic Medicine
Disclosure: Nothing to disclose.

Medical Editor

Carmel Armon, MD, MSc, MHS, Professor of Neurology, Tufts University School of Medicine; Chief, Division of Neurology, Baystate Medical Center
Carmel Armon, MD, MSc, MHS is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Association of Neuromuscular and Electrodiagnostic Medicine, American Clinical Neurophysiology Society, American College of Physicians, American Epilepsy Society, American Medical Association, American Neurological Association, American Stroke Association, Massachusetts Medical Society, Movement Disorders Society, and Sigma Xi
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Neil A Busis, MD, Chief, Division of Neurology, Department of Medicine, Head, Clinical Neurophysiology Laboratory, University of Pittsburgh Medical Center-Shadyside
Neil A Busis, MD is a member of the following medical societies: American Academy of Neurology and American Association of Neuromuscular and Electrodiagnostic Medicine
Disclosure: Nothing to disclose.

CME Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants
Nicholas Y Lorenzo, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Neurology
Disclosure: Nothing to disclose.

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