Benign Essential Blepharospasm is a disorder associated with atypical spasms or blinking of the eyelids. The condition arises as a result of the inability to control the muscle contractions around the eyelids, leading to involuntary blinking of eyelids in an abnormal manner. Benign essential blepharospasm is different from the temporary twitching of eyelids as it is more of a neurological disorder or dystonia.
What is Benign Essential Blepharospasm?
Benign essential blepharospasm is a type of dystonia that causes involuntary spasms and contractions of muscles of eyelids. The condition is a progressive neurological disorder, in which the frequency of the blinking of eye is abnormally high, causing severe irritation in the eyes and at times, it even becomes painful.
For a normal patient, the blink of eye is called as the tonic blink, which is an involuntary action causing the contact between the upper and the lower eyelid to allow lubrication of the front eye. When tonic blinking increases in frequency it leads to several disorders, among which one is benign essential blepharospasm.
Symptoms of Benign Essential Blepharospasm
The common signs and symptoms of benign essential blepharospasm are:
- Uncontrolled winking and squinting of eyes.
- Spasms of eye muscles.
- Sensitivity towards light.
- Forced blinking of eyes.
- Difficulty in opening the eyes.
- Irritation in the eye.
- Eyelid spasms get worse and more frequent with the passage of time.
- Reduction in the facial muscle tone.
Epidemiology of Benign Essential Blepharospasm
Benign essential blepharospasm incidence rate can go up to 2000 each year with a prevalence of around 5 in 100,000 individuals.
Prognosis of Benign Essential Blepharospasm
The outlook for individuals ailing from benign essential blepharospasm is not great, owing to the progressive nature of the condition. The condition worsens and gradually affects the adjacent muscles. A significant amount of relief can be achieved by botulin toxin treatment, but some side effects are a part and parcel of it like blurred vision, drooping eyelids, double vision and dryness in the eye.
Causes of Benign Essential Blepharospasm
The exact reason behind benign essential blepharospasm still remains a mystery, but there are definitely some speculations around it. These are:
- Recurrent Infantile Reflex as a Cause of Benign Essential Blepharospasm: Reflex blinking is a common phenomenon amongst fetuses aged 6 months or less, which occurs in response to stimulation present around it. In case of benign essential blepharospasm, these reflexes may return and affect the individuals without hampering the intellectual functions.
- Biochemical Imbalance in Basal Ganglia to Cause Benign Essential Blepharospasm: The neurons present in the basal ganglia may deviate from the regular biochemical pathway and induce benign essential blepharospasm.
- Benign Essential Blepharospasm due to Genetic Inheritance: Benign essential blepharospasm could be inherited as an autosomal dominant trait, but the instances are quite rare to support it.
- Secondary Diseases Leading to Benign Essential Blepharospasm: Benign essential blepharospasm may also occur as a secondary disease to diseases like corneal abrasion, oral-facial-digital syndrome type 3, CS gas exposure, Salzmann’s nodular degeneration of cornea, chloroacetophenone, Meige blepharospasm-oromandibular dystonia syndrome, recurrent corneal erosion, congenital glaucoma and idiopathic orofacial dystonia.
Pathophysiology of Benign Essential Blepharospasm
The pathophysiology behind benign essential blepharospasm is believed to be the improper functioning of the mid brain, brain stem and basal ganglia, rather than just the basal ganglia. The abnormality is not just confined to a specific locus; but it lies within the entire cortical processing of sensory neurons leading to inability in controlling the blink reflex.
Risk Factors of Benign Essential Blepharospasm
The probable risk factors that pose a threat for benign essential blepharospasm are:
- Facial injury.
- Trauma to the head and brain.
- Presence of benign essential blepharospasm cases within the family.
- Administration of drugs like antihistamines, benzodiazepines, dopamine and sympathomimetic drugs.
Complications of Benign Essential Blepharospasm
The complications that can arise as a consequence of benign essential blepharospasm are:
- Dryness in eyes.
- Onset of eye diseases like keratoconjunctivitis and blepharitis.
- Patients may develop Parkinson’s disease, cerebral diplegia and Hungtington’s disease.
Diagnosis of Benign Essential Blepharospasm
The characteristic symptoms of benign essential blepharospasm help in the diagnosis. Also, benign essential blepharospasm can be diagnosed using the Blepharospasm Disability Index, which checks for the extent of impaired function due to benign essential blepharospasm. Another scale called the Jankovic Rating Scale is used to determine the frequency and the associated severity of the blinking of eyelids. Together, the above scales provide the clear picture to analyze the type of treatment which is suitable for the patient.
Other than the above scales, benign essential blepharospasm can also be diagnosed using the following tests:
- Vision tests to check the health of the eye.
- Diabetes test to check for nerve neuropathy.
Treatment of Benign Essential Blepharospasm
There is no cure for benign essential blepharospasm, but treatments do exist to provide relief from the symptoms that arise. The treatments available are both surgical as well as non-surgical. These include:
- Non-surgical Treatment for Benign Essential Blepharospasm: These are usually the first line of treatment for benign essential blepharospasm. It includes:
- Artificial Tears: These can be applied to the eyes to check the dryness.
- Sunglasses: Tinted sunglasses can be worn to block the UV radiations and prevent the pain due to photosensitivity.
- Eyelid Hygiene: Following proper eye lid hygiene helps in checking the irritation with in the eye.
- Oral Drugs: Oral medications like benzodiazphines, tetrabenazine and antispasmodiacs help in checking the spasms and contractions.
- Botulinum Toxin Injections: The Botox injections are obtained from Clostridium botulinum bacteria. The extract is injected in both the eyelids to provide relief from the spasms and contractions by causing the paralysis of the injected muscle.
- Deep Brain Stimulation: It helps in stimulating the brain cells in order to retrieve the complete and effective functioning from the cells.
- Surgical Treatment Methods for Benign Essential Blepharospasm: Surgery is the last resort for benign essential blepharospasm when the nonsurgical measures fail to prove to be enough and vision gets impaired severely. The surgical measures that can be opted are:
- Myectomy: This surgery involves the removal of protractor orbicularis muscle that undergoes involuntary contractions and spasms.
- Extended Myectomy: In this type of surgery, the procerus and corrugator superciliaris muscles are removed along with the protractor orbicularis muscle to check the involuntary contractions and spasms.
Prevention of Benign Essential Blepharospasm
Benign essential blepharospasm can be prevented by following certain preventive measures like checking the intake of alcohol, nicotine and caffeine, management of stress and anxiety and sleeping as much as possible when the eyelids twitch.
Benign essential blepharospasm is a neurological disorder of rare occurrence, in which the ailing individuals suffer from muscle contraction and spasms that are involuntary as well as intermittent in nature. The common symptoms that arise due to benign essential blepharospasm are uncontrollable blinking of eyelids, blurred vision, dryness and irritation in the eyes. The real cause behind benign essential blepharospasm is still not known, but most speculations suggest a biochemical imbalance in the sensory unit of basal ganglia. Several treatments and medications are available for benign essential blepharospasm, but the most commonly administered are the Botox injection that helps in stabilizing the eyelids. Surgical measures are also available, in case the non-surgical measures fail to provide the required relief.
- “Benign Essential Blepharospasm.” Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/benign-essential-blepharospasm/symptoms-causes/syc-20372305
- “Benign Essential Blepharospasm Information Page.” National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/All-Disorders/Benign-Essential-Blepharospasm-Information-Page
- Defazio, G., Hallett, M., & Jinnah, H. A. (2013). Development and validation of a clinical guideline for diagnosing blepharospasm. Neurology, 81(3), 236-240.
- Lee, M. S., Lee, J. Y., Kim, J. M., Ahn, J., Piao, Y. S., & Ji, H. J. (2018). Diagnosis of benign essential blepharospasm: correlation of clinical features, electromyography, and response to botulinum toxin. Journal of Clinical Neurology, 14(4), 546-551.