What is Blepharospasm?
Blepharospasm is a type of focal dystonia in which there is involuntary contraction of the muscles of the eyelids causing closure of the lids. This does not have any effect on a person's vision or mental faculties. The only time vision would be affected is if the contractions become so extreme that they force the eyelids closed. Symptoms include frequent blinking and irritation of the eye. Dry eye has also been noted to be present with blepharospasm. Other involuntary movements can occur in addition to blepharospasm such as forceful opening of the jaw, retraction of the lips, or protrusion of the tongue.
The cause is unknown, though patients should be evaluated for diseases that may also have blepharospasm as a symptom. Although the cause of blepharospasm is unknown, it is possibly due to abnormal function of the basal ganglia of the brain. The job of the basal ganglia is to help with the start and continuation of movement. What is unknown about this is what makes the basal ganglia function incorrectly.
Who gets Blepharospasm?
The cause of blepharospasm is unknown although there are likely genetic factors. Diet, exercise, or similar events cause it. Most often individuals with blepharospasm are seemingly randomly afflicted. It is possible for it to be inherited, but this is rare. Those that are inherited also usually have a generalized dystonia. Blepharospasm is not fatal but is usually a life-long condition.
How is Blepharospasm diagnosed?
Blepharospasm is diagnosed by the clinical evaluation. It may occasionally be difficult to diagnose. Usually it is necessary for the doctor to evaluate the information provided from the patient, and the physical and neurological examinations to provide the diagnosis. Electrodiagnosis is an important tool in the diagnosis of blepharospasm.
How is Blepharospasm treated?
Treatment includes three areas of focus: oral medications, botulinum toxin injections (which work the best), and surgery. Each of these can be used separately, or in combination with the others to provide the best treatment. Botulinum toxin injections are given to weaken the muscles that close the eyes. This slight weakening allows patients with blepharospasm to have more control opening their eyes. The injection of botulinum toxin may be performed using electromyographic (EMG) guidance. An injectable electrode attached to an EMG machine allows the muscle to be identified and the toxin injected precisely into the muscle.
Oral methylphenidate (Ritalin, Novartis) has been reported to alleviate symptoms of benign essential blepharospasm in an off-label application. These patients exhibit refractory periorbital and facial dystonias, including blepharospasm, apraxia of eyelid opening, and oromandibular dystonia unresponsive to standard treatments who experienced a response to oral methylphenidate therapy. While the mechanisms for facial dystonias have not been elucidated, there is evidence to suggest that they are on the spectrum with Parkinson disease. Given the role of dopamine loss in the pathogenesis of Parkinson, methylphenidate may be acting on the pathway directly involved in facial dystonias. There are a few cases of successful treatment of blepharospasm refractory to upper eyelid myectomy with methylphenidate monotherapy.