Essential blepharospasm and related dystonias.

Essential blepharospasm is an idiopathic disorder of progressive involuntary spasms of the orbicularis oculi and upper facial (corrugator, procerus) muscles. Blepharospasm literally means spasm of the eyelids; however, most patients with blepharospasm also have or will develop squeezing in the lower face and neck muscles (Meige's syndrome, orofacial dystonia, or oromandibular dystonia). Some patients develop dystonic, uncontrolled movements in areas outside the facial nerve distribution (segmental cranial dystonia or craniocervical dystonia). Chronic, forceful squeezing by the periocular muscles becomes debilitating for the patient and leads to functional and cosmetic eyelid deformities. Treatment has included a variety of modalities and oral medications that are of limited efficacy. Botulinum-A toxin injections have delivered the best temporary relief from this disorder, while the periorbital myectomy operation has been shown to give the best long-term results.