title: Animal model explains the origins of the cranial dystonia benign essential blepharospasm.
abstract: The current study demonstrates that combining two mild alterations to the rat trigeminal reflex blink system reproduces the symptoms of benign essential blepharospasm, a cranial dystonia characterized by uncontrollable spasms of blinking. The first modification, a small striatal dopamine depletion, reduces the tonic inhibition of trigeminal reflex blink circuits. The second alteration, a slight weakening of the lid-closing orbicularis oculi muscle, begins an adaptive increase in the drive on trigeminal sensory-motor blink circuits that initiates blepharospasm. By themselves, neither of these modifications causes spasms of lid closure, but combined, they induce bilateral forceful blinking and spasms of lid closure. A two-factor model based on these rodent experiments may explain the development of benign essential blepharospasm in humans. The first factor, a subclinical loss of striatal dopamine, creates a permissive environment within the trigeminal blink circuits. The second factor, an external ophthalmic insult, precipitates benign essential blepharospasm. This two-factor model may also be applicable to the genesis of other cranial dystonias.
authors.affiliation: Department of Neurobiology and Behavior, State University of New York at Stony Brook, 11794-5230, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Schicatano
authors.forename: M A
authors.initials: MA
authors.lastname: Basso
authors.forename: C
authors.initials: C
authors.lastname: Evinger
mesh_terms: D000818:Animals; D001479:Basal Ganglia / Q000502:physiology; D001764:Blepharospasm / Q000503:physiopathology*; D001767:Blinking / Q000502:physiology*; D004195:Disease Models, Animal; D004292:Dominance, Cerebral / Q000502:physiology; D004298:Dopamine / Q000502:physiology; D004421:Dystonia / Q000503:physiopathology; D004576:Electromyography; D008297:Male; D009415:Nerve Net / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted; D014276:Trigeminal Nerve / Q000503:physiopathology*
chemical_list: D004298:Dopamine