Botulinum A toxin injection is the best temporary therapy and myectomy is the best long term therapy. It is a unilateral facial squeezing disorder unrelated to essential blepharospasm. Hemifacial spasms affect only those muscle innervated by the facial nerve. It usually begins around the eye with periodic twitching and spasms of the eyelids that close the eye partially or completely. The condition does not cause pain but it may with time slowly cause weakness of the facial muscles involved.
Hemifacial spasm differs etiologically from essential blepharospasm.
It is most commonly caused by compression of the facial nerve by normal and abnormal vascular structures at the level of the brain stem, e.x. In other cases, in spite of neuroimaging of the brain or even exploratory surgery, no cause can be found. . Hemifacial spasm may be treated by medication, injection of Botulinum toxin or surgery. Botulinum toxin therapy is simple to perform and can be very effective in diminishing the spasms. Unlike blepharospasm, hemifacial spasms seem to have a longer duration of effect and may have 4 to 6 months and, occasionally, up to 9 months of relief.