What are the causes of blepharospasm and how is it treated?

What Causes Blepharospasm and How Is It Treated?

Blepharospasm is a focal dystonia caused by involuntary contractions of the orbicularis oculi and periocular muscles, and botulinum toxin injection into the affected muscles is the definitive first-line treatment, providing meaningful improvement in over 85% of patients. 1

Understanding Blepharospasm vs. Blepharitis

It's critical to distinguish blepharospasm from blepharitis, as these are entirely different conditions that are often confused due to similar names:

• Blepharospasm is a neurological movement disorder characterized by involuntary, sustained eyelid closure due to dystonic muscle contractions 1, 2
• Blepharitis is chronic eyelid margin inflammation causing irritation and redness 3

The question appears to ask about "blepharism," which likely refers to blepharospasm (the neurological condition), not blepharitis.

Causes and Pathophysiology of Blepharospasm

Etiology

Blepharospasm is a multifactorial condition where unknown genetic factors combine with epigenetic and environmental factors to reach the disease threshold. 2

• The exact cause remains elusive despite 40 years of research since Marsden first characterized it as adult-onset focal dystonia 2
• It should be considered a network disorder involving multiple brain regions, not solely a basal ganglia problem 2
• Family history of dystonia is present in some patients, suggesting genetic susceptibility 4

Clinical Manifestations

Patients experience prolonged spasms of the orbicularis oculi muscles as the clinical hallmark, but the presentation is heterogeneous: 2

• Various types of involuntary periocular muscle activation 2
• Motor features including excessive blinking, impaired eyelid opening, and spasms of eye closure 5
• Nonmotor manifestations including psychiatric symptoms, mild cognitive disturbances, and sensory abnormalities 2
• Some patients develop apraxia of eyelid opening (inability to voluntarily open eyes despite lack of spasm) 4
• Disease may spread to other craniocervical regions, particularly cervical dystonia with anterocollis 4

Treatment of Blepharospasm

First-Line Treatment: Botulinum Toxin Injections

Botulinum toxin type A injection is the mainstay of treatment and should be the initial therapeutic approach for all patients with blepharospasm. 1

Standard Botulinum Toxin Products

• OnabotulinumtoxinA and incobotulinumtoxinA provide meaningful improvement in over 85% of patients 1
• Effects typically last 3-4 months before wearing off 1
• Injection technique matters: pretarsal injections into the pars pretarsalis of the orbicularis oculi muscle are essential for certain patients 5

Novel Botulinum Toxin Option

For patients with severe, poorly controlled blepharospasm despite high-dose standard botulinum toxin products, daxibotulinumtoxinA represents a promising alternative. 6

• Provides faster onset and extended duration of effect compared to traditional formulations 6
• Patients may retain 50-75% efficacy at 3 months post-injection 6
• Particularly useful for refractory cases or those experiencing decreased response over time 6

Identifying Pretarsal Blepharospasm

Electromyographic assessment should be performed in patients with primary failure to botulinum toxin injections to identify pretarsal blepharospasm. 5

• Pretarsal blepharospasm involves selective abnormal activity of the pars pretarsalis of the orbicularis oculi muscle 5
• These patients are often functionally blind before proper treatment 5
• Selective pretarsal injections of botulinum toxin induce significant improvement, with 50% of patients regaining normal or near-normal vision 5
• This excellent response is sustained with repeated pretarsal injections 5

Bridging Therapy During Botulinum Toxin Wear-Off

Apraclonidine 0.5-1% ophthalmic solution (2 drops to each eye) provides useful short-term symptom relief during premature wearing off of botulinum toxin effects. 1

• This alpha-2 adrenergic receptor agonist causes contraction of the superior tarsal (Müller) muscle, improving blepharospasm-related eyelid closure 1
• Provides transient improvement lasting approximately 2-4 hours 1
• Blinded video ratings showed reduction in severity scores from 3.4 to 2.3 (p<0.025) 1
• No adverse effects were noted in clinical studies 1

Surgical Options for Refractory Cases

For difficult-to-treat blepharospasm, particularly with apraxia of eyelid opening, myectomy combined with substantial doses of botulinum toxin into pretarsal orbicularis oculi muscles may be required. 4

• Deep brain stimulation has shown marked improvement in patients with associated anterocollis 4
• These interventions are reserved for therapeutically challenging cases 4

Clinical Pearls and Common Pitfalls

Key Diagnostic Considerations

• Not all patients present with the same motor and nonmotor symptoms, making blepharospasm phenomenologically heterogeneous 2
• Severity assessment tools should account for both motor and nonmotor manifestations 2
• Consider electromyographic evaluation if standard botulinum toxin injections fail 5

Treatment Optimization

• Injection technique is critical: pretarsal injections are essential for certain subtypes 5
• Patients experiencing premature wear-off should be offered apraclonidine as bridging therapy rather than early re-injection 1
• Consider switching to daxibotulinumtoxinA for patients with poor symptom control on standard formulations 6
• Recognize that blepharospasm with apraxia of eyelid opening and anterocollis represents a particularly challenging subphenotype requiring aggressive multimodal treatment 4