Blepharospasm is a rare progressive neurological disorder characterized by involuntary muscle contractions and spasms of eyelid. As like most scientific terms, its origin is from two Greek words, ‘Blepharon’ meaning ‘Eyelid’ and ‘Spasmos’ denoting ‘uncontrolled muscle contraction’. The disease has the literal meaning of ‘abnormal blinking’ or ‘eyelid twitch’. The muscle contractions are uncontrollable and often painful.
Benign Essential Blepharospasm(BEB)
Synonymously, Blepharospasm is said as ‘Benign Essential Blepharospasm(BEB)’ to distinguish it from less serious secondary blinking disorders, where ‘Benign’ denotes the condition that is not life threatening and the medical term ‘Essential‘ for unknown cause for the disease. But BEB can be differentiated from Blepharospasm that it can exist as a part of a specific syndrome (Eg: Meige syndrome) or systemic disease (Eg: Extra pyramidal diseases)
BEB can be medically defined as bilateral condition and a form of focal dystonia characterized by episodic contraction of eyelid protractor muscles.
It is a type of blepharospasm associated with photophobia and ocular signs of blepharitis.
Blepharospasm has the diagnosis code of ICD9 333.81 under International Classification of Diseases.
Blepharospasm is idiopathic in nature, as the exact causes for the disease are still unknown. Yet, functional neuro-imaging suggests that it might be due to the dysfunction within basal ganglia. Rare cases of genetics are also observed.
The average onset of the disease is 56 and it is seen most commonly between 40–60 tears of age. Female are more prone to the disease than male with ratio of 2–4:1 ratio respectively. 2000 cases are diagnosed annually in U.S.
Not all patients experience similar symptoms for the disease and also the onset is acute without any warning symptoms. It may begin with gradual increase in blinking and eye irritation. Some people may experience fatigue, emotional tension, bright light sensitivity. As condition progresses more frequent symptoms and facial spasms may develop. However symptoms abate during sleep.
In advanced cases, functional blindness may occur due to long time periodic inability to open eyes. When associated with Meige’s syndrome facial grimacing occurs.
The disease appears to be multi factorial with various risk factors as follows:
Head or facial trauma causing damage in the basal ganglia leading to concussions
Dry eye and dystonias
Blepharitis, intra-ocular inflammation and related eye infections
Certain drugs used to treat Parkinson’s disease and estrogen treatment therapy for women during menopause
Both prolonged usage and acute withdrawal of psycho-active drugs like benzodiazepines
And as like every other disease, the multi potential “stress”
Since the disease has an acute onset and multi-factorial origin, there are no common preventive measures. However avoiding inciting irritants (Bright light and the like), treatment of underlying diseases (Like Blepharitis, dry eyes, etc), stress management and decreasing of causal medication dosage or usage of alternative medications, can help in prevention.
The clinical diagnosis is difficult as it takes the careful history taking and physical examination for symptoms. Neuroradiologic studies rarely helps.
First line treatment
Periodic injection of Botulinum toxins, Botulinum toxins A, Incobotulinum toxin A, Abobotulinum, obtained from the species, Clostridium botulinum is the FDA approved effective treatment for the disease. These toxins cause muscle weakening and blocks nerve impulses. They are injected into the orbicuaris oculi muscle every 3–4 months with 2.5 to 5 units per injection site and 4–8 injection sites per eye. The toxin, like any neuroblocking agents, prevents the fusion of acetylcholine vesicles with the cell membrane.
However minority of the patients show no effect for the drug. According to a cross sectional survey, among 100 patients 22% are benefited and 69% showed no effect.
This is suggested for persons with poor response for botulinum toxins and other drugs. As it is a neuromuscular disease, both neuroctomy and myectomy can be applied.
Protractor myectomy( Removal of muscles responsible for eyelid closure)
Myectomy of orbital and palpebral orbicularis( upper, sometimes lower)
Surgical ablation of facial nerve
Second line treatment
Oral medications like muscle relaxants and sedatives are rarely used for treatment. Usage of FL-41 tinted glasses for photosensitivity in reflex blepharospasm is advised.
Other drug therapies
Certain other drugs like anticholinergic drugs, dopaminergic drugs and Dopamine receptor antagonists are also used. However botulinum toxins are the mainstay with other therapies on the horizon.
Therapies like biofeedback, acupuncture, hypnosis, chiropractic, nutritional are also other options.
Dysport(Type A), Myobloc(Type B) are drugs under investigation for FDA approval.
Affordability of treatment
The botox is available commercially at price of INR 250 per unit. Calculating the number of units per injection sites and number of injection sites per eye, and comparing it with the Indian Per Capita income of India estimated by World Bank in 2013–14 (INR 74,920), the treatment cost affects more than 10% of the persons expenses per time, and hence giving hard time to them.
Reduced D2 receptor for treatment
Magnetic resonance Studies for diagnosis of plasticity and trigeminal sensitization
Defazio, Giovanni. 2009. Epidemiology of blepharospasm
Berardelli, Alfredo. 2009. Cranial dystonias: pathophysiology.
Evinger, Craig. 2009. Using animal models to understand benign essential Blepharospasm.
Impediments for therapeutic advancements
Idiopathic nature of the disease
Small sample size with few number of patients
Heterogenous population( Mixture of age onset, distribution and etiology of the disease)
Faulty experimental designs
Irina Belinsky, MD , Samuel Baharestani, MD, Cat Nguyen Burkat, MD FACS, Andrew Go Lee MD, on Blepharospasm at Eyewiki.aao.org
Blue book on Benign Essential Blepharospasm, Meige, and other related disorders by BEB Research Foundation
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Evinger, Craig. 2009.,Using animal models to understand benign essential Blepharospasm.
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BEB in Genetics Home Reference
Amy Hellman and Diego Torres-Russotto , Botulinum toxin in the management of blepharospasm: current evidence and recent developments in Therapeautic Advancements in Neurologial Disorders, 2015 March
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