What is blepharospasm
Blepharospasm is an involuntary contraction of the muscles of the eyelid, usually caused by a state of suffering of the eye.
Chronic and bilateral spasms define essential benign blepharospasm (BEB), a focal dystonia that leads to episodic closure of both eyelids. The BEB must be distinguished from secondary blepharospasm, which can occur in association with systemic diseases, neurological problems or specific eye conditions.
The preferred treatment of blepharospasm is the periodic injection of botulinum toxin A into the eye's orbicular muscle.
Note. Blepharospasm is a neurological condition that belongs to the group of disorders known as dystonias, variable due to symptoms, causes, course and treatments. Dystonias are generally characterized by involuntary muscular contractions, which force the body to abnormal and, sometimes, painful movements and postures.
Symptoms
In the early stages, blepharospasm manifests itself with mild and occasional contractions, which arise only as a result of specific trigger factors, such as exposure to intense light, fatigue and emotional tension. Spasms do not cause pain, but they can be very annoying. In the case of essential benign blepharospasm (BEB), over time the intermittent closing of the eyelids becomes more and more intense and frequent, especially during the day, and can be associated with facial spasms. In advanced cases, these episodes can cause functional blindness due to the inability to open the eyes temporarily. This can severely limit the performance of daily life activities, such as reading and driving.
Blepharospasm may be characterized by a gradual increase in eye irritation and photophobia. Some people may also experience fatigue or emotional tension. Symptoms may decrease or cease while a subject is sleeping or concentrating on a specific task. Sometimes, blepharospasm can be the first sign of a chronic movement disorder, especially when, in addition to the continuous contraction of the eyelids, other spasms of the face develop; for example, when blepharospasm is part of Meige syndrome (a chronic facial dystonia) it is associated with uncontrolled facial movements.
Blepharospasm may be secondary to eye disorders, including those that cause eye irritation (for example: blepharitis, trichiasis, corneal foreign body, dry keratoconjunctivitis, etc.) and systemic neurological disorders associated with spasms (for example: Parkinson's disease).
Symptoms can be aggravated by fatigue, intense light and stress.
Symptoms of blepharospasm include:
- Dry eyes;
- Sensitivity to sunlight;
- Excessive movement of the eyelids and spasms, usually characterized by uncontrollable eyelid closure, of longer duration than the typical corneal reflex, sometimes of several minutes or hours;
- Intermittent twitching of the eye muscles and in the surrounding area of the face. Some patients have involuntary spasms that radiate to the neck and nose. Other movements may occur in addition to blepharospasm, such as, for example, forced jaw opening, lip retraction or tongue protrusion.
Blepharospasm should not be confused with:
- Ptosis : lowering of the eyelids, which can be caused by weakness or paralysis of the levator palpebrae;
- Blepharitis : inflammation of the eyelids due to infections or allergies;
- Hemifacial spasm : non-dystonic condition that involves various muscles on one side of the face; it is caused by irritation of the facial nerve. Muscle contractions are more rapid and transient than those of blepharospasm and the condition is always one-sided.
Causes and risk factors
The mechanism underlying blepharospasm is not yet clear. Some tests obtained by functional neuroimaging suggest a dysfunction of the basal ganglia, nerve areas located at the base of the brain, which control the coordination of muscular movements. Other possible mechanisms include sensitization of the trigeminal system and hyperactivity of the seventh cranial nerve, which induces strong simultaneous contractions of the eyelid muscles. In rare cases, genetic implications have been reported in the development of blepharospasm.
The exact cause of essential benign blepharospasm (BEB) is unknown and, by definition, this dystonia is not associated with another disease or syndrome.
Involuntary eyelid contractions can be caused or aggravated by:
- Alcohol, tobacco or caffeine abuse;
- Environmental irritants, such as wind, lights, sun or air pollution;
- Insomnia, fatigue, stress or anxiety;
- Irritation of the surface of the eye or eyelids (conjunctiva).
Blepharospasm can be triggered by the side effects of some drugs, such as those used to treat Parkinson's disease, as well as hormone therapies, including estrogen replacement for menopausal women. Blepharospasm may also be an acute withdrawal symptom from benzodiazepines. In addition to being associated with their suspension, prolonged use of these drugs is a known risk factor for the development of the disorder. In some rare cases, blepharospasm may be caused by facial trauma or head injury due to damage to the basal ganglia.
The following conditions may precede or accompany the disorder:
- Blepharitis;
- Dry eyes;
- entropion;
- Sensitivity to light;
- Conjunctivitis;
- trichiasis;
- Uveitis.
Undiagnosed corneal abrasions can also cause chronic eyelid contractions. Very rarely, eyelid spasms are a symptom of a more severe nervous system disorder. When blepharospasm is the result of these conditions, it is almost always accompanied by other characteristic symptoms; some of these include:
- Bell's palsy (facial paralysis);
- Cervical dystonia (spasmodic torticollis);
- Oromandibular and facial dystonia;
- Multiple sclerosis;
- Parkinson;
- Tourette syndrome (characterized by involuntary and tic movements).
Diagnosis
The diagnosis of blepharospasm is confirmed by a careful history and physical examination to determine the cause of the continuous movement of the eyelids and to exclude associated eye diseases and any underlying neurological disorders.
Neuroradiological studies are generally of limited use. The history is very important for the diagnosis and allows the doctor to distinguish between primary blepharospasm (BEB) and secondary. In many cases, no cause is found. The doctor may observe the involuntary contraction of the eyelid muscles during an episode of blepharospasm.
The eyelid contractions are rarely severe enough to require emergency medical treatment. However, chronic spasms can be a symptom of more serious nervous system disorders. You may need to consult your doctor if you experience chronic eyelid spasms or any of the following symptoms occur:
- The contraction is not resolved within a few weeks;
- The contraction begins to affect other parts of the face;
- The eyelid is drooping and the eye is red, sore or has an unusual secretion;
- The eyelid closes completely with each contraction or the patient has difficulty opening the eyes.
Treatment
To date, there is no definitive cure for blepharospasm, although several treatment options can reduce its severity. For the management of secondary blepharospasm it is obviously necessary to treat the basic condition.
Botulinum toxin
Periodic injection of botulinum toxin A is the treatment of choice for blepharospasm. This therapy allows to induce partial and localized paralysis. Botulinum toxin A is administered directly into the eye's orbicular muscle and injections are repeated regularly, every 3-4 months, with variations based on the patient's response. Usually, therapy provides almost immediate relief from blepharospasm symptoms (although for some this may take more than a week). In certain patients, botulinum toxin reduces its effectiveness after many years of use.
Complications associated with treatment include: bruises, blepharoptosis, ectropion, epiphora, diplopia, lagophthalmos and corneal exposure. Usually, these are all transient effects and related to the spread of the toxin to adjacent muscles. The central portion of the pretarsal orbicular muscle is avoided to minimize the possibility of inducing palpebral ptosis.
Pharmacological therapy
Oral medications, such as muscle relaxants and sedatives, have limited utility in the treatment of blepharospasm and produce unpredictable results. These can alleviate mild symptoms or allow the intervals between injections to be prolonged.
Surgery
Surgery is reserved for patients who are poorly sensitive to botulinum therapy. The myectomy of the orbicular muscle (orbital and palpebral portion), and the surgical ablation of the facial nerve are effective in the treatment of blepharospasm. However, this last procedure was mostly abandoned, due to the high recurrence rates and the incidence of hemifacial paralysis.
