Sunday, 2 October 2011

Focal myokymia is not always benign

Level 3

Epub ahead of printBarmettler et al. Eyelid Myokymia: Not Always Benign. Orbit. 2011 Sep 29.

A 33-year-old otherwise healthy male presented with a week-long history of isolated right lower eyelid myokymia. Two weeks later, the patient's myokymia had progressed to include twitching of the right brow and right upper lip. Imaging revealed multiple demyelinating lesions consistent with multiple sclerosis. A review of eyelid and facial myokymia, along with possible concerning causes is provided, geared towards the oculoplastic surgeon. Eyelid myokymia, typically a benign condition, may rarely evolve into facial myokymia reflective of underlying brainstem disease.

"I have always taught that focal myokymia is benign and does need investigation. Almost everyone recalls having an episode themselves. As a runner I tend to get focal myokymia frequently after a long run. Focal myokymia is often related to stress, excessive caffeine intake and sleep deprivation."

"Superior oblique myokymia presents with intermittent oscillopsia and dilopia that is characteristic; the images shimmer with a vertical deviation."

"Please don't get focal myokymia mixed up with facial myokymia, which is unilateral rippling movements across the facial muscles this is much more sinister and usually indicates brain stem pathology, for example demyelination."

"An important learning point is that patients, in particular healthcare professionals, think focal myokymia is due to fasciculations and that they have motor neurone disease. In general fasciculations cannot be felt and can only be seen. The exception to the latter is macro-fasciculations that occur when the anterior horn cell innervating very large motor units degenerate; this typically occurs in the post-polio syndrome."

"If treatment is necessary, for example in superior oblique myokymia, I would recommend carbamazepine or oxcarbazepine. In theory other sodium channel blockers should also be effective." 

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