Blepharospasm is a neurological disorder characterized by intermittent, involuntary spasms and contractions of the orbicularis oculi (eyelid) muscles around both eyes.[1][2][3] These result in abnormal twitching or blinking, and in the extreme, closure of the eyes.
The word blepharospasm is derived from the Greek: βλέφαρον / blepharon, eyelid, and σπασμός / spasmos, spasm, an uncontrolled muscle contraction. The condition should be distinguished from the more common, and milder, involuntary quivering of an eyelid, known as myokymia or fasciculation.
Blepharospasm is one form of a group of movement disorders called dystonia.[3] It may be a primary or secondary disorder. The primary disorder is benign essential blepharospasm, in which term the qualifier essential indicates that the cause is unknown. Blepharospasm may occur as secondary to conditions including dry eyes and other specific ocular disease or conditions, Meige's Syndrome and other forms of dystonia, and Parkinson's Disease and other movement disorders.[2]
Blepharospasm occurs in middle age and is more frequent among women than men. The most common first line treatments are medication and injections of botulinum toxin into the eyelid protractor muscles.
Epidemiology
Blepharospasm is a fairly rare disease. Estimates of incidence and prevalence vary, tending to be higher in population studies than service studies,[4] likely because of delays in diagnosis.[3] In the United States, approximately 2,000 new cases of blepharospasm are diagnosed each year.[5] Estimates of incidence per million persons-years range from 14.5 in Northern California[6] to 100 in Taiwan.[7] Estimates of prevalence per million range from 12 in Olmsted County, Minnesota[8] to 133 in Puglia, Southern Italy.[9]
The onset of blepharospasm tends to be during the ages 40-60.[7][9] The condition is twice or more frequent among females than males,[6][7] which may be related to menopause.[10][11] In Taiwan, the condition was found to be more frequent among white-collar workers.[7]
Signs and symptoms
Blepharospasm usually begins with occasional twitches of both eyelids, which progress over time to forceful and frequent spasms and contractions of the eyelids. In severe episodes, the patient cannot open their eyelids (apraxia), which severely limits their daily activities. Prolonged closure of the eyelids may result in functional blindness.[3]
Patients suffering from blepharospasm also report sensory symptoms including sensitivity to light,[12][13] dry eyes,[14] and burning sensation and grittiness in the eyes.[3] Although such symptoms tend to precede the onset of the blepharospasm, they may both be due to a common third factor.[15]
Typically, the symptoms---spasms and contractions of the eyelids---tend to worsen when the patient relaxes but abate during sleep.[16] The symptoms may be temporarily alleviated by sensory tricks (geste antagoniste) including stretching or rubbing the eyebrows, eyelids, or forehead,[17] and singing, talking, or humming.[18] Blepharospasm is aggravated by fatigue, stress, and environmental factors such as wind or air pollution.[19]
Although blepharospasm is defined as a bilaterally symmetric disorder that affects both eyes, some research has reported unilateral onset.[20][21]
Causes
Historically, it was believed that blepharospasm was due to the abnormal functioning of the brain's basal ganglia.[22] The basal ganglia are structures in the brain that are involved in the regulation of motor functions.
However, blepharospasm is now known to involve several regions of the brain and to be a multifactorial condition in which "one or several as yet unknown genes together with epigenetic and environmental factors combine to reach the threshold that induces the disease".[2]
Blepharospasm is often associated with dry eyes, but the causal mechanism is still not clear.[14][7] Research in New York and Italy suggests that increased blinking (which may be triggered by dry eyes) leads to blepharospasm.[23][24] A case control study in China found that blepharospasm aggravated dry eyes.[25]
Some drugs can induce blepharospasm, including those used to treat depression[32] and Parkinson's disease.[33]Hormone replacement therapy for women going through menopause has been found to be associated with dry eyes,[11] which in turn is associated with blepharospasm.
Blepharospasm can be caused by concussions in some rare cases, when a blow to the back of the head damages the basal ganglia.[34]
Blepharospasm is associated with exposure to the sun.[35]
Diagnosis
No laboratory tests exist with which to definitively diagnose blepharospasm. Historically, the condition was frequently misdiagnosed,[16] often as a psychiatric condition.[5]
Diagnosis of blepharospasm has been enhanced by the proposal of objective diagnostic criteria that start from "stereotyped, bilateral and synchronous orbicularis oculi spasms" and proceed to the identification of a "sensory trick" or "increased blinking".[36] The criteria have been validated across multiple ethnicities in multiple centers.[37]
Treatment
Standard treatments of blepharospasm include drugs, injections of botulinum toxin, and surgery to remove the eyelid muscle.
Drug therapy for blepharospasm has proved generally unpredictable and short-termed. Anticholinergics, tranquillizing drugs and botulinum toxin are the mostly used therapeutic options. However serious side effects can be observed as well as failure of therapy. It is therefore not surprising that new therapies are constantly being tested. In this backdrop new evidence shows Mosapride can be a safe and affordable therapeutic option for blepharospasm.[38]
Botulinum toxin injections have been used to induce localized, partial paralysis.[39] Among most sufferers, botulinum toxin injection is the preferred treatment method.[40] Injections are generally administered every three months, with variations based on patient response and usually give almost immediate relief (though for some it may take more than a week) of symptoms from the muscle spasms. Most patients can resume a relatively normal life with regular botulinum toxin treatments. A minority of sufferers develop minimal or no result from botulinum toxin injections and have to find other treatments. For some, botulinum toxin diminishes in its effectiveness after many years of use. An observed side effect in a minority of patients is ptosis or eyelid droop. Attempts to inject in locations that minimize ptosis can result in diminished ability to control spasms. A recent Cochrane systematic review showed that a single treatment session (where both eyelids were injected with BtA multiple times) alleviated the symptoms of blepharospasm, disability, and number of involuntary movements.[41]
People that do not respond well to medication or botulinum toxin injection are candidates for surgical therapy. The most effective surgical treatment has been protractor myectomy, the removal of muscles responsible for eyelid closure.[42]
Although there is no cure, botulinum toxin injections may help temporarily.[43] A surgical procedure known as myectomy may also be useful.
Since the root of the problem is neurological, doctors have explored sensorimotor retraining activities to enable the brain to "rewire" itself and eliminate dystonic movements. The work of Joaquin Farias has shown that sensorimotor retraining activities and proprioceptive stimulation can induce neuroplasticity, making it possible for patients to recover substantial function that was lost due to blepharospasm.[44][45][46]
^Adams WH, Digre KB, Patel BC, Anderson RL, Warner JE, Katz BJ (July 2006). "The evaluation of light sensitivity in benign essential blepharospasm". American Journal of Ophthalmology. 142 (1): 82–87. doi:10.1016/j.ajo.2006.02.020. PMID16815254.
^Hwang, WJ (2012). "Demographic and Clinical Features of Patients with Blepharospasm in Southern Taiwan: a university Hospital-Based Study". Acta Neurol Taiwan. 21: 108–114 – via PubMed: 23196730.
^Farias, Joaquin (2016). Limitless. How your movements can heal your brain: An essay on the neurodynamics of dystonia. Galene Editions. ISBN978-0-9951701-0-0.
^Farias, Joaquin (2012). Intertwined. How to Induce Neuroplasticity: A New Approach to Rehabilitating Dystonias. Galene Editions. ISBN978-8-4615512-4-8.
^Farias, J., Sarti-Martínez, MA. Title: "Elite musicians treated by specific fingers motion program to stimulate propiceptive sense", Congreso Nacional De La Sociedad Anatómica Española, Alicante (España), European Journal of Anatomy, p. 110