Myokymia is defined as fluctuating hyperexcitability of muscle fibers caused by repetitive spontaneous contraction of motor units.
Myokymia is generally benign with self-resolution, although symptomatic treatment with
benzodiazepines,
anticonvulsants, and muscle relaxants can be used.
Botulinum toxins can also be utilized, although they are mostly used for symptomatic
facial myokymia. Here, we report two patients who developed
continuous myokymia, resulting in secondary
hypertrophy, stiffness, and discomfort in the affected muscles. The first patient had a history of a tethered spinal cord and developed
continuous myokymia in the S1 and S2 radicular regions of the left leg. The second patient underwent
radiation therapy for
lung cancer and developed
brachial plexopathy with abnormal activity in the muscles supplied by the musculocutaneous nerve in the right arm. Both patients experienced sleep disturbance, focal discomfort, and
restlessness. The
anticonvulsants and muscle relaxants were ineffective.
Chemodenervation with
botulinum A toxin was initiated using either
onabotulinumtoxinA or
abobotulinumtoxinA. Both patients experienced a substantial reduction in
myokymia, with ongoing reversal of muscle
hypertrophy and significant improvement in reported subjective symptoms. Treatment with
botulinum toxins can be highly effective in patients with symptomatic segmental continuous hypertrophic
myokymia and may be considered first-line
therapy.