What is myokymia?
Myokymia is the continuous undulation of a group of muscle fibers caused by the successive spontaneous contraction of motor units.
On EMG, they appear as groups of 2 to 10 potentials, firing at 5 to 60 Hz and recurring regularly at 0.2- to 1-second intervals.
Myokymia, frequently observed in facial muscles, occurs in a number of brainstem diseases, especially multiple sclerosis, radiation-induced nerve damage, Guillain–Barré syndrome, chronic peripheral nerve disorders, timber rattlesnake envenomation, gold therapy, and Isaacs’ syndrome.
