2.1 Introduction

Blepharospasm is a dystonia of the facial musculature that ranges in severity from an increased blink rate to disabling contractions with pain and visual dysfunction. As with other dystonias, it is understood to be a complex neurologic disorder with abnormalities in sensory input, central processing, and motor output, interacting to produce the movement disorder. ¹

The primary muscle involved in blepharospasm is the orbicularis oculi. Other protractors of the eyelids include the corrugator superciliaris and procerus muscles. Spasms are usually bilateral but may affect one side primarily. Blepharospasm most commonly presents as a focal dystonia but can be part of a syndrome called “Meige syndrome,” a segmental cranial dystonia consisting of blepharospasm with oromandibular and sometimes cervical or laryngeal dystonia (see Chapter 4). ² Blepharospasm is uncommon, with an estimated prevalence of up to 1 case per 10,000 people. There is an increased female to male prevalence. The mean age of diagnosis is in the sixth decade of life. ³ The condition usually begins with increased blink rate or spasms of the eyelids, forehead, or midfacial muscles. Patients often complain of eye irritation, pain, photophobia, or abnormal tearing, and may initially be diagnosed with various other ocular disorders. Spasms may be triggered by sensory stimulation such as wind, air pollutants, or bright light, and may be worse in stressful situations. Some patients identify sensory tricks such as touching the face, using artificial tears, or talking and singing that may temporarily abate the spasm. The condition is often progressive and results in functional blindness in a minority of those affected. ⁴ Patients may avoid social settings, reading, driving, or watching television, with ensuing anxiety and depression. Maximum disability is reached at an average of 3 years after onset.

Although severity may fluctuate, spontaneous remissions are rare. Over the long term, the persistent contractions can result in weakening of the eyelid’s fascial attachments, resulting in brow ptosis, dermatochalasis, and ectropion, with further visual field obstruction. The disease typically remains focal but may involve other facial muscles or, rarely, other parts of the body.

Management begins with ruling out and treatment of any underlying eye disorder such as blepharitis, conjunctivitis, or corneal irritation, and with lid hygiene and lubrication. Tinted sunglasses with ultraviolet blocking have demonstrated efficacy as well. ⁵ Some patients resort to “eyelid crutches” or springs on glasses to hold lid open. Systemic medications such as benzodiazepines and the antiparkinsonian agent trihexyphenidyl (Artane) have limited efficacy and significant adverse effects. ² Surgery is reserved for patients who fail more conservative treatments. Neurectomy of facial nerve branches has generally been abandoned in favor of myectomy of the eyelid protractors.

Botulinum neurotoxin (BoNT) injection has emerged as a treatment of choice for blepharospasm, and it is approved by the United States Food and Drug Administration (FDA) for this application. Many studies ranging from large open label to small double-blind placebo-controlled have demonstrated BoNT injection to be both effective and safe, with success rates exceeding 90%. ^{6 ,​ 7 ,​ 8 ,​ 9 ,​ 10 ,​ 11 ,​ 12 ,​ 13 ,​ 14} Recently, the Guideline Development Subcommittee of the American Academy of Neurology reviewed current evidence and outcomes for treatment of blepharospasm. Given the rise in use of different forms of BoNT, including Botox (onabotulinumtoxinA), Dysport (abobotulinumtoxinA), and Xeomin (incobotulinumtoxinA), the subcommittee also reviewed studies comparing these different formulations. Randomized controlled trials comparing Botox and Dysport showed comparable benefits between the two. Observational studies comparing long-term outcome were also reviewed, and sustained benefits were noted with Botox, Dysport, and Xeomin. Overall, they concluded that BoNT is considered the first-line treatment of blepharospasm by most movement disorder specialists and all type A toxins appear to have similar efficacy and can continue to be efficacious over long periods. ¹⁵ Other studies have examined a flexible versus fixed treatment schedule with the use of BoNT. Bladen et al found that, over a period of 10 years, flexible onabotulinumtoxin provided better long-term relief for facial dystonia than a fixed regimen. Flexible interval treatment appeared to provide better patient satisfaction and longer duration of effect compared to fixed treatment with similar complication rates. ¹⁶ Similarly, a recent cross-sectional survey of patients receiving BoNT for blepharospasm indicated that flexible, individualized treatment plans may improve satisfaction and outcomes. ¹⁷