Benign essential blepharospasm (BEB) is an idiopathic disorder of progressive involuntary spasms of orbicularis oculi and upper facial muscles leading to closure of eyelids. BEB is a bilateral condition and a form of focal dystonia (repetitive involuntary sustained muscle contraction) characterised by episodic contraction of protractor (drawing a part forward) muscles (orbicularis oculi, procerus and corrugator superciliaris) and is not associated with another disease. Severe blepharospasm may temporarily make patient functionally blind. Blepharospasm may be precipitated by factors such as reading, bright light, driving or stress and alleviated by talking, relaxation or walking.
BEB should be differentiated from blepharospasm that can exist as part of specific condition (secondary blepharospasm) such as:-
Meige’s syndrome: Meige’s syndrome is characterised by blepharospasm with involvement of the lower facial and neck muscles.
Breughel’s syndrome: Breughel’s syndrome (oromandibular dystonia) is association of blepharospasm with severe mandibular and cervical muscle involvement.
Extrapyramidal disorders: Systemic disease such as extrapyramidal disorders may be present with blepharospasm.
Reflex blepharospasm: Reflex blepharospasm may be secondary to irritation of ocular surface.
Benign essential blepharospasm may have following symptoms:-
Symptoms preceding diagnosis are:-
- Watering of eyes.
- Intolerance of light.
- Vague ocular pain.
Early symptoms of blepharospasm are:-
- Increased rate of blinking.
- Eyelid spasms.
- Irritation of eyes.
- Midfacial or lower facial spasm.
- Brow spasm.
- Eyelid Tic (habitual spasmodic muscular contraction)
Exact cause of benign essential blepharospasm is not known.
Some evidence using functional neuroimaging studies, suggests dysfunction within basal ganglia.
Rarely, genetics play a role in some cases. Some patients with blepharospasm have at least one first degree relative with some form of focal dystonia. Rarely, it may be inherited as an autosomal dominant condition.
- Variable risk factors are there for blepharospasm such as:-
- Injury to head or face.
- Reflex blepharospasm may be triggered by filamentary keratitis, intraocular inflammation, severely dry eyes, blepharitis, or light sensitivity.
- Family history of dystonia or tremor.
Blepharospasm may be associated with the use of medications such as:-
- Benzodiazepines: Prolonged use or acute withdrawal of benzodiazepines.
- Dopaminergic drugs: Use of dopaminergic drugs e.g. in patients with Parkinson’s disease.
- Antihistaminics: Use of antihistaminics as in nasal decongestants.
- Sympathomimetic drugs.
Conditions which may occur together with BEB are:-
- Dry eyes.
- Some patients have blepharitis and keratoconjunctivitis.
- Other neurologic disorders:-
- Parkinson’s disease.
- Parkinson plus syndromes e.g. supranuclear palsy and corticobasal degeneration.
- Huntington’s disease
- Cerebral diplegia.
In normal blinking, eyelid closure results due to the activity and co-inhibition of two groups of muscles, the protractors of the eyelid and the voluntary retractor of the eyelids (e.g. levator palpebrae superioris, frontalis muscle). During normal blink, protractors and retractors function at separate times, so that on activation of protractor muscles, there is inhibition of retractors. In blepharospasm, this inhibition between protractors and retractors is lost.
Diagnosis of BEB is made clinically (based on history and physical examination) and it is a diagnosis of exclusion by ruling out the presence of associated conditions.
Benign Essential Blepharospasm:
At onset of BEB, there is increased frequency of blinking precipitated by stimuli such as wind, sunlight, noise, air pollution, reading, watching television, stress, or movement of eye or head. Patients may develop sensory tricks (‘geste antagoniste’) to relieve symptoms such as tics and movements of other muscles innervated by facial nerve e.g. whistling, coughing, eating, picking teeth, yawning or chewing gum.
Eyelid spasm, a characteristic feature of blepharospasm, sets in a few months to years after early features. Blepharospasm is unilateral to begin with but usually eventually evolves into a bilateral condition. Blepharospasm usually lasts for minutes to hours together. Blepharospasm has a variable course and may be intermittent or continuous. It is slowly progressive in most of the patients.
Excessive blinking may lead to unilateral mild twitches, but may progress to bilateral, frequent and forceful spasms. During severe episodes, patient is unable to open the eyelids which may be associated with severe pain and functional blindness and may interfere with daily routine activities. Severe blepharospasm may cause high level of distress and psychosocial impairment causing anxiety, depression, avoidance of social contact and occupational problems. Blepharospasm reduces while concentrating on a specific task or during sleep.
Blepharospasm may be associated with apraxia (loss of ability to perform activity) of eyelid opening i.e. inhibition of proper functioning of levator palpebrae superioris muscle. Apraxia is especially common in parkinsonian disorders.
- Meige’s syndrome: Meige’s syndrome may be associated with facial grimacing due to facial dystonia.
- Breughel’s syndrome: Breughel’s syndrome is a dystonia of motor trigeminal nerve which produces widely open mouth. There is paroxysmal hyperpnoea (increased depth of breathing) and upbeating nystagmus.
- Extrapyramidal disorders: Patients with extrapyramidal disorders may show other abnormal movements such as tics or cogwheel rigidity of neck and extremities.
- Reflex blepharospasm: Reflex blepharospasm may occur due to dry eye or ocular irritation from light.
Conditions relieving blepharospasm:
- Inferior gaze.
- Artificial tears.
- Traction on eyelids.
- Solving crossword.
- Doing maths.
- Solving puzzles.
Anatomic changes associated with long-standing blepharospasm may be:
- Ptosis (drooping of upper eyelid in relation to eyeball): Ptosis of the upper eyelid may occur due to attenuation and disinsertion of levator palpebrae superioris aponeurosis (broad sheetlike tendon).
- Eyebrow ptosis (drooping): Eyebrow ptosis may result from weakened fascial support caused by longstanding spasm, leading to stretching of fascia.
- Dermatochalasis: Dermatochalasis is defined as excess of skin in eyelid and is produced by stretching of skin due to blepharospasm.
- Skin excoriation: Skin excoriation is produced secondary to manual attempts by patient to open lids.
- Entropion: Blepharospasm may lead to spastic entropion.
- Canthal tendon abnormalities: Stretching of medial and lateral canthal tendons may produce horizontal lid laxity and therefore, may cause entropion or ectropion of lower lids. Stretching may produce lid fissures also.
- Phimosis (short and narrow) of palpebral fissure (opening between eyelids): Bepharospasm may lead to phimosis of palpebral fissure.
Blepharospasm may be differentiated from conditions like:
- Ocular myokymia: Ocular myokymia is characterised by spontaneous, fine fascicular contractions of orbicularis oculi muscle without muscular weakness or atrophy. Eyelid myokymia is typically unilateral and it commonly involves lower eyelids.
- Secondary to meningeal irritation.
- Facial tics or Tourette syndrome: Facial tics are repetitive stereotyped movements or vocalisations such as blinking, sniffing, facial movements or tensing of abdominal muscles.
- Hemifacial spasms (contraction of one side of face): It usually begins as fasciculations of periocular orbicularis and surrounding muscles, which spreads to involve lower facial muscles innervated by facial nerve. Spasms are myoclonic, involuntary, aggravated by stress and may persist during sleep. Hemifacial spasm may lead to facial weakness.
Management should be under medical supervision.
Currently, there is no cure for BEB and the disease frequently progresses despite treatment.
- Sunglasses: Wearing tinted sunglasses with ultraviolet blocking may help in decreasing painful light sensitivity in those who show significant photosensitivity.
- Lid hygiene: Lid hygiene may decrease eye irritation. Those having blepharitis also show improvement.
- Artificial tears: Application of artificial tears and punctal occlusion to alleviate dry eyes may improve blepharospasm.
- Botulinum A toxin: Subcutaneous Botulinum A toxin injected along upper and lower eyelid and eyebrow gives temporary relief. The toxin interferes with transmitter acetylcholine release from nerve terminals and cause paralysis of injected muscle. Botulinum A toxin is derived from anaerobic, gram-positive bacteria named Clostridium botulinum.
Surgical management of BEB is usually reserved for patients who are unresponsive or cannot tolerate to botulinum injections.
Surgery can be:
- Myectomy: Myectomy involves removal of protractor orbicularis oculi muscle.
- Extended myectomy: Extended myectomy involves removal of protractor orbicularis oculi, procerus and corrugator supercilliaris muscles.