Myokymia results from complex bursts of repetitive discharges of a motor unit typically attributable to a demyelinating condition. We report a 12-year-old girl with unilateral trigeminal myokymia who presented with involuntary jaw movements. Electromyography demonstrated unilateral rhythmic myokymic discharges in the left masseter and temporalis muscles at a rate of 3.5 Hz. Abnormal jaw movements spontaneously resolved over 8 months without treatment or residual deficits. The pathophysiology of myokymic discharges is discussed. (J Child Neurol 2003;18:572—574).
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