myokymia

Continuous involuntary quivering or rippling of muscles at rest, caused by spontaneous, repetitive firing of groups of motor unit potentials. SYN: fibrillary chorea, Morvan chorea. [myo- + G. kyma, wave]

- facial m. m. that appears in the facial muscles, causing narrowing of the palpebral fissure and continuous undulation of the facial skin surface; the latter is referred to as “bag of worms” appearance and is best seen with reflected light; due to intrinsic brainstem lesion, such as a pontine glioma or multiple sclerosis.

- generalized m. widespread m., present in multiple limbs and often the face; of various causes, including Isaac syndrome, uremia, thyrotoxicosis and gold toxicity (gold-m. syndrome).

- hereditary m. [MIM*160100] a syndrome consisting of muscle contractions and night cramps; autosomal dominant inheritance.

- limb m. m. present in one or more limbs; various causes, one of the more common being prior plexus radiation.

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n.

prominent quivering of a few muscle fibres, not associated with any other abnormal features. It is a benign condition. See also fasciculation.

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myo·kym·ia (mi″o-kiґme-ə) [myo- + Gr. kyma wave] a benign condition marked by brief spontaneous tetanic contractions of motor units or groups of muscle fibers, usually adjacent groups of fibers contracting alternately. Called also myoclonia fibrillaris multiplex.