What is Benign Essential Blepharospasm?
Benign essential blepharospasm (BEB) is a type of focal cranial dystonia characterized by involuntary contractions of the orbicularis oculi muscle resulting in eye closure. Dystonia is a type of movement disorder and is characterized by either sustained or intermittent contraction of a muscle leading to abnormal repetitive movements or postures. Blepharospasm is a focal dystonia (focal means affects one body part) characterized by the simultaneous contraction of agonist and antagonist muscles, resulting in involuntary eyelid closure.
The estimated prevalence of benign essential blepharospasm worldwide is 20 to 133 cases per million and varies by geographic area. Blepharospasm is less common than cervical dystonia in the United States and Europe. However, in Italy and Japan, blepharospasm is more common than cervical dystonia.
- Benign essential blepharospasm (BEB) is a focal cranial dystonia resulting in eyelid closure.
- Female gender and age over 50 increase your risk of BEB.
- Treatment may include surgery, pharmaceuticals, and Botox injections.
Understanding Benign Essential Blepharospasm
Patients with BEB have an increased blinking rate and an increased response in the R2 phase of the trigeminal blinking reflex (TBR). Basal ganglia dysfunction, overactivity of the seventh nerve leading to simultaneous forceful contractions of the eyelid protractors and retractors, ion channelopathy, and sensitization of the trigeminal system by photophobia are some proposed mechanisms of BEB.
The spasm associated with blepharospasm tends to be synchronous and bilateral with variable symptoms. BEB symptoms can range from mild with increased blinking rate to functional blindness due to persistent muscle contraction. In many cases, the disease is progressive, initially presenting with contractions limited to the orbicularis oculi muscles and later extending to the musculature of the lower face and neck, which is known as Meige syndrome.
The etiology of blepharospasm is not well understood, but it is thought more than one factor must be present for the disease to occur. The two-hit hypothesis proposes that a predisposing factor and an environmental trigger must be present together for the disease to develop.
Risk Factors for Benign Essential Blepharospasm
Blepharospasm is more common in postmenopausal women. Women often present with a higher symptom frequency and severity. Incidence also increases with age and peaks between the ages of 50 to 70.
Risk factors may be genetic or non-inherited. Some gene mutations have been implicated in the development of the disease; 20% to 30% of cases have a positive family history. Other factors which are thought to cause BEB include neurotransmitter dysregulations, structural damage, and previous underlying eye disorders.
Many environmental risk factors are associated with an increased risk of developing BEB, including urbanization and working ‘white-collar’ jobs associated with a high-stress lifestyle. Reading, watching television, and computer screen use are thought to increase eye strain and may exacerbate BEB. Lastly, 42.6% of patients experienced some sort of stressful life event before the onset of symptoms.
Benign Essential Blepharospasm Symptoms
The primary symptom of BEB is involuntary muscle contractions and spasms of the eyelid muscles aggravated by fatigue or stress.
Diagnosing Benign Essential Blepharospasm
A comprehensive patient history can be helpful in determining the diagnosis. Patients with BEB will complain of bilateral, synchronous spasm of the orbicularis oculi muscle. These spasms may be brief repetitive blinking or a persistent closure of the eyes leading to visual impairment.
There is a diagnostic algorithm that is based on the presence of bilateral, synchronous, and stereotyped movements of the orbicularis oculi muscle, the presence of a sensory trick, or increased blinking. This diagnostic algorithm has been shown to have a sensitivity of 93% and a specificity of 90% in differentiating BEB from other similar conditions.
Benign Essential Blepharospasm Treatment
Because the exact cause of BEB is not well understood, there is no definitive cure. Treatment options include photochromatic modulation, botulinum toxin injection, oral medications, and surgical management. Botox, a first line treatment for BEB, is periodically injected into the eyelid protractor muscles including the orbicularis oculi, corrugator supercilii, and procerus muscles.
BEB is associated with dry eyes and photophobia, which should be treated accordingly. Psychiatric disorders, such as anxiety and depression, are associated with BEB and may require treatment.