What is Benign Essential Blepharospasm?

Blepharospasm
Causes and symptoms
Risk factors
Epidemiology
Diagnosis and treatment
References
Further reading


Benign essential blepharospasm (BEB), a form of focal dystonia, is a disorder of involuntary spasms involving the eyelid protractor muscles. First reported in Western medical literature in 1857, BEB can have debilitating functional and social effects.

Benign essential blepharospasm
Benign essential blepharospasm is a disorder of involuntary spasms involving the eyelid protractor muscles. Image Credit: Gorodenkoff/Shutterstock.com

It usually starts with more frequent eyelid blinking episodes, and while the severity of the spasms varies, many cases proceed to the point where the patients are functionally blind. The cause of BEB is unknown, but several pathophysiological pathways have been proposed.

Severe photophobia has also been linked to the disorder, which may continue even after the motor spasms have been effectively controlled.

Blepharospasm

Blepharospasm is when the orbicularis oculi muscles contract involuntarily, resulting in an accelerated rate of bilateral eyelid closure. Dystonia is a kind of blepharospasm.

Dystonia is a type of movement disorder that is characterized by muscle contractions that are either continuous or intermittent. This results in abnormal repeated motions or postures with a distinct pattern, which may be twisting or tremulous. Voluntary action often causes dystonia to worsen by overactivating muscles in most dystonias.

The most prevalent type of blepharospasm, benign essential blepharospasm (BEB), is late-onset focal dystonia with an unclear cause.

Causes and symptoms

Blepharospasm has an unknown etiology. Several gene mutations have been linked to the disease's development: 20 to 30% of cases have a positive family history of benign essential blepharospasm (BEB), and some genes have been linked to a higher risk of acquiring the condition.

Neurotransmitter dysregulations, structural damage, and previous underlying eye illnesses will likely play a role in the disease's development.

The disease's specific pathophysiology is yet unknown. There have been numerous pathophysiological processes proposed. Genetic, environmental, functional, and structural factors are among the pathophysiologic pathways involved and are not mutually exclusive.

In reality, many of these elements must be present in a single patient for the disease to occur. This is backed by the two-hit hypothesis, which states that a predisposing factor and an environmental trigger must both be present simultaneously for a disease to occur.

It usually starts with more frequent eyelid blinking bouts, and while the severity of the spasms varies, many cases proceed to the point where the patients are functionally blind.

Although the predominant clinical hallmark of blepharospasm is persistent spasms of the orbicularis oculi muscles, it can also be accompanied by involuntary activation of the periorbital muscles.

Sensory tactics, such as caressing the side of the eye, humming, or singing, are widely used by patients with BEB to relieve spasms momentarily.

Patients with BEB frequently experience depression and anxiety. These can occur before the disease or as a result of it. Half of BEB patients experience ocular symptoms, with the majority reporting eye dryness and photophobia.

One-third of patients are diagnosed with BEB during the first year of symptom onset, another third between one and five years, and the other one-third take longer than five years to be diagnosed.

Risk factors

Driving, reading, stress, bright lighting, and other activities have been identified as BEB-triggering causes. Singing, humming, walking, talking, and relaxing can help relieve blepharospasm, and in rare cases, applying pressure to 'trigger sites' can help relieve an incident of blepharospasm.

Patients with psychiatric disorders such as obsessive-compulsive disorder, depression, and anxiety are at a higher risk of developing blepharospasm. Ophthalmic symptoms such as burning, dryness, or grittiness have been found to occur in 40-60% of patients before the development of blepharospasm.

Furthermore, diseases of the anterior segment, such as keratoconjunctivitis/blepharitis, are linked to an increased risk of developing blepharospasm, though this is more accurately referred to as "secondary blepharospasm" because the condition improves once the underlying conditions are properly treated.

Numerous affected individuals within families suggest a genetic predisposition to the condition. The inheritance pattern appears autosomal dominant with low penetrance in such situations. GNAL, CIZ1, TOR1A, DRD5, and REEP4 genes are linked to BEB formation.

Epidemiology

The global prevalence of benign essential blepharospasm is estimated to range from 20 to 133 cases per million, depending on geographic location. In the United States and Europe, blepharospasm is less prevalent than cervical dystonia.

Blepharospasm, on the other hand, is more common in Italy and Japan than cervical dystonia. A population-based study looked into the patient demographics and risk factors for BEB in a broad Asian population and discovered that the annual incidence of BEB in Taiwan is 10 cases per 100,000.

The annual incidence of BEB climbed from 0.04 in 2010 to 0.13 in the following ten years.

Blepharospasm occurs more commonly in women than in men. Menopause is regarded to be one of the contributing causes of a higher incidence of blepharospasm in women.

Blepharospasm affects 2.3 times more women than men. Women may also have a higher frequency and intensity of symptoms. Blepharospasm is most common in people between the ages of 50 and 70.

Diagnosis and treatment

Blepharospasm is diagnosed mostly through clinical examination. It is critical to get a clinical history to determine the cause of the eyelid spasm. Blepharospasm patients will have bilateral, synchronous, stereotyped spasms of the orbicularis oculi muscle.

The presence of various movements of the orbicularis oculi muscle, the presence of a sensory trick, or increased blinking are all part of a diagnostic strategy. This diagnostic method has been found to distinguish BEB from other similar disorders with a sensitivity of 93% and a specificity of 90%.

When assessing patients for BEB, it is critical to rule out reflex (secondary) blepharospasm, which is the most prevalent cause of eyelid spasms and is usually caused by ocular surface disease.

As the etiology of benign essential blepharospasm is unknown, there is no definitive treatment for BEB. There are, however, a variety of therapy choices. Patients treated with photochromatic modulation have shown clinical improvement in multiple studies.

The FL-41 lens tint, in particular, has been demonstrated to improve photophobia symptoms in patients with blepharospasm.

Oral medication for BEB has failed to provide long-term relief from symptoms, and its success varies from patient to patient. Benzodiazepines, anticholinergics, levodopa, and baclofen are examples of such drugs.

Patients who do not respond to medical treatment and have persistent symptoms may benefit from surgical intervention. The goal of surgical management is to improve functionality and reduce the frequency of spasms.

References

Further Reading

Last Updated: Sep 5, 2023

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