Blepharospasm and Hemifacial Spasm

Abstract

Blepharospasm and hemifacial spasm are the main facial muscle hyperactivity disorders seen in the ophthalmology clinic. They are characterized by stereotyped patterns of involuntary muscle twitching and are associated with functional blindness from eye closure, embarrassing disfigurement, and diminished quality of life. Blepharospasm, apraxia of eyelid opening, facial myokymia, eyelid myokymia, and their related syndromes are part of a family of focal facial dystonias. They are movement disorders distinct in pathophysiology and clinical presentation from hemifacial spasm. In both, diagnosis is clinical and further neuroimaging workup is warranted in atypical cases. Hemifacial spasm is most commonly caused by vascular compressive lesions at the facial nerve root exit zone of the brainstem, but it can also be mimicked by aberrant regeneration with synkinesis after an episode of Bell’s palsy. Treatment of facial muscle hyperactivity is largely symptomatic and temporary, primarily involving injections of botulinum toxin to weaken affected musculature, with a high short-term success rate in symptomatic control. In addition to chemodenervation, a variety of oral medications have been tried, and treatment of any associated neurologic disease is recommended. Particularly with refractory hemifacial spasm, neurosurgical intervention may be helpful.KeywordsEyelidEyebrowBenign essential blepharospasmEssential blepharospasmBlepharospasmHemifacial spasmDystoniaBotulinum toxinBotoxChemodenervationApraxiaApraxia of eyelid openingOrbicularis oculiOrbicularis orisMuscleMeigeFacialInjectionMyokymiaBell’s palsySynkinesisAberrant regenerationFacial myokymiaEyelid myokymiaClostridium botulinumOnabotulinumtoxinA (Botox®Botox Cosmetic®)IncobotulinumtoxinA (Xeomin®)AbobotulinumtoxinA (Dysport®)RimabotulinumtoxinB (Myobloc® or Neurobloc®)Facial nerveCranial nerve 7Facial nerve root exit zone (FEZ)Arteriovenous malformations (AVM)Anterior inferior cerebellar artery (AICA)Posterior inferior cerebellar artery (PICA)Vertebrobasilar arteryBasilar artery