Myokymia Workup

Updated: Oct 19, 2016
  • Author: Suying L Song, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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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.

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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.

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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.

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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.

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