Abstract
A young woman presented with facial myokymia in association with dermatomyositis. There was no evidence of peripheral neuropathy. Needle electromyography showed prominent myokymic discharges and brief neuromyotonic discharges in addition to many small-amplitude, short-duration motor unit potentials. Myokymia and dermatomyositis both responded to immunosuppressive treatment. The presence of antibodies to voltage-gated potassium channels and the association with dermatomyositis indicated an autoimmune cause for myokymia, which may have been due to reversible peripheral nerve hyperexcitability.
MeSH terms
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Action Potentials / physiology
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Adult
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Autoantibodies / immunology
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Cyclophosphamide / therapeutic use
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Dermatomyositis / complications*
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Dermatomyositis / pathology
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Dermatomyositis / physiopathology*
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Facial Nerve Diseases / etiology*
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Facial Nerve Diseases / pathology
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Facial Nerve Diseases / physiopathology*
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Female
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Humans
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Immunoglobulins, Intravenous / therapeutic use
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Isaacs Syndrome / etiology*
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Isaacs Syndrome / pathology
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Isaacs Syndrome / physiopathology*
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Methylprednisolone / therapeutic use
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Muscle, Skeletal / immunology
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Muscle, Skeletal / pathology
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Muscle, Skeletal / physiopathology*
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Phenytoin / therapeutic use
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Potassium Channels, Voltage-Gated / immunology*
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Potassium Channels, Voltage-Gated / metabolism
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Prednisone / therapeutic use
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Recurrence
Substances
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Autoantibodies
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Immunoglobulins, Intravenous
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Potassium Channels, Voltage-Gated
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Phenytoin
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Cyclophosphamide
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Prednisone
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Methylprednisolone