Definition of Blepharospasm
Blepharospasm is an adult-onset focal dystonia characterized by involuntary, bilateral, synchronous contractions of the orbicularis oculi muscles, resulting in involuntary eyelid spasms, increased blinking, and eye closure. 1, 2
Core Clinical Features
Involuntary muscle contractions: The hallmark is bilateral, synchronous, and symmetric spasms of the orbicularis oculi muscles that patients cannot voluntarily control 3
Variable presentation patterns: Patients may exhibit different types of movements including:
Progressive nature: Often begins with increased blinking and progresses to sustained involuntary eye closure that can be functionally disabling 2
Associated Features
Motor manifestations beyond the primary spasm pattern include:
- Apraxia of eyelid opening (difficulty voluntarily opening the eyes even when spasms are not present) 1, 3
- Extension to lower face, jaw, or cervical muscles in some patients 1
Non-motor manifestations that may accompany the condition:
- Psychiatric disturbances
- Mild cognitive changes
- Sensory abnormalities 2
Sensory tricks (geste antagoniste): Many patients discover maneuvers that temporarily reduce spasms, such as touching the face or wearing sunglasses 3
Pathophysiology
Network disorder: Current evidence indicates blepharospasm involves dysfunction across multiple brain regions, not solely the basal ganglia, with abnormalities in sensorimotor circuits and dopamine systems 4, 2
Multifactorial etiology: The condition likely results from genetic susceptibility combined with epigenetic and environmental factors reaching a disease threshold 2
Clinical Context
Primary vs. secondary: The term "primary blepharospasm" (or "benign essential blepharospasm") refers to cases without identifiable underlying cause, distinguishing it from secondary causes of eyelid spasm 1, 5
Differential diagnosis considerations: Blepharospasm must be distinguished from other conditions causing eyelid abnormalities, including incomplete eyelid closure from other causes, eyelid malposition, and neurological conditions like Bell's palsy 5
Treatment implications: Type A botulinum toxin (including onabotulinumtoxinA, incobotulinumtoxinA, and abobotulinumtoxinA) is the treatment of choice, with the American Academy of Neurology stating these formulations are equally effective and should be considered for treatment 5, 6, 1