Blepharospasm is defined as an abnormal, involuntary, sustained and forceful closure or twitching of the eyelids. It is derived from the Greek word ‘blepharon’ which means eyelid, and ‘spasm’ which is an uncontrolled muscle contraction. Blepharospasm is usually associated with headache, eyebrow strain and occasionally loss of vision.
Isolated blepharospasm is rare and represents a minority of patients presenting with blepharospasm. Blepharospasm is commonly associated with lower facial spasms as part of a syndrome or disease complex. Some examples are:
Meige Syndrome: Characterized by spasm of the eyelids and midface.
Brueghel’s Syndrome: Presents with blepharospasm and marked spasms in the lower face and neck.
Segmental Cranial Dystonia: In addition to the usual spasms of the eyelids and facial muscles it is associated with spasms along distribution of various cranial nerves, most commonly involving the Facial Nerve.
Generalized Dystonia: Presents with spasms across various body parts in addition to blepharospasm and facial spasms.
Epidemiology and Statistics of blepharospasm
Blepharospasm typically affects women in the age group of 40 to 60 years, with 2 to 4 women afflicted for every man affected by the disease. In the US, 2000 cases of blepharospasm are diagnosed every year with a prevalence of 5 per 100,000 people. Currently, there are around 50,000 diagnosed cases of blepharospasm in the United States.
Although mortality due to the disease is almost non-existent being a benign condition, it can be severely disabling with eye pain and functional blindness. There are also reported cases of severe depression and even suicides associated with severe and disabling blepharospasm.
Historical Trivia about Blepharospasm
Blepharospasm has had a dismal past in terms of historical misadventure. The earliest record of blepharospasm and lower facial spasm is a 16th Century painting called ‘De Gaper’ and during that period it was common practice to institutionalize those suffering from blepharospasm and lower facial spasm in mental asylums. This unfortunate practice continued for several centuries until major breakthrough was made in its diagnosis and treatment by Henry Meige, a French neurologist in the early 20th century. For his contribution, the symptom complex of eyelid and midface spasms with dystonia is given the eponym, Meige Syndrome. Henderson’s classic article on bleparospasm was published in 1956 and exhaustively described the disability with various treatment options.
Various treatment modalities such as alcohol injections into the facial nerve, facial nerve avulsion, neurotomy and neurectomy were developed during the same period but their results were often even more dreadful than the disease itself. However, recent developments in the treatment have shown marked improvement in the outcome of the disease.
Essential or spontaneous blepharospasm is a rare focal dystonia without any known cause and affects individuals between 45 and 65 years of age. Although idiopathic in nature, essential blepharospasm is commonly associated with stress, fatigue or an irritant. The symptoms may possibly be benign and transient or might cause significant lifelong challenges to the individual and even cause functional blindness in those rare cases.
Reflex blepharospasm is due to reflex sensory stimulation through branches of the Trigeminal nerve and is common in conditions like phlyctenular conjunctivitis, interstitial keratitis, corneal foreign body, corneal ulcers and iridocyclitis. Excessive stimulation of the retina by dazzling light, stimulation of facial nerve due to central causes, and some hysterical patients also present with reflex blepharospasm. It is due to any pain in and around the eye.
Pathophysiology of Blepharospasm
Although still in the dark, it is understood that blepharospasm is a neuropathologic disorder and not due to some psychopathology as was believed in the past. The aetiology of blepharospasm is multifactorial cannot be pin-pointed to a central regulatory area somewhere in the basal ganglia, midbrain or brainstem.
The current view is that blepharospasm occurs due to a defective circuitry and not just a defective focus. To understand this better we need to understand the circuit that controls blinking. The circuit consists of a sensory limb, a control center located in the midbrain, and a motor limb.
Various stimuli such as corneal or eyelid irritation, pain, emotion, stress and other nerve stimulants trigger the sensory limb of the circuit.
This sensory stimuli are transmitted to a defective control center in the midbrain which is weakened by age, injury or genetics. This defective center results in a failure to regulate the positive feedback mechanism.
The abnormal positive feeback signals are unregulated in the motor pathway which causes uncontrolled contractions of various muscles in the distribution of facial nerve and its nucleus. The muscles commonly involved are orbicularis oculi, corrugator superciliaris and procerus of the eyelids and other muscles of facial expression ultimately resulting in contortion of the face and blepharospasm.
Clinical Presentation of Blepharopasm
The diagnosis of blepharospasm is a clinical one and investigations are futile as there is no specific observable pathology. The onset of blepharospasm is marked by a gradually progressive increase of blinking in response to innocuous stimuli like wind, polluted air, sunlight, noise, movements of the head or eyes, or exposure to any stressful environment. They also present with dry eye symptoms such as photophobia and eye irritation. These symptoms are however relieved by sleep, relaxation, gazing downwards, artificial tears, traction on eyelids, talking, humming or singing.
Initially, it starts in one eye but progresses gradually to involve both eyes and even the facial and neck muscles.
The following symptoms occur during the early stages of blepharospasm:
Increased rate of blinking
Spasms of the eyelids
Irritation of the eyes
Midfacial or lower facial spasm
Following anatomic changes are seen with long-standing blepharospasm:
Due to its rarity and its similarities with other diseases, blepharospasm is often misdiagnosed. Following conditions should be considered in the differential diagnosis while evaluating a suspected case of blepharospasm:
Blepharospasm: It refers eyelid muscles around the eye which close involuntarily. This may possibly cause loss of vision, especially while reading, headaches, and eyebrow strain. The early symptoms of blepharospasm include increased blink rate (77%), eyelid spasms (66%), eye irritation (55%), midfacial or lower facial spasm (59%), brow spasm (24%), and eyelid tic (22%).
Ptosis:Ptosis is sometimes referred to as Blepharoptosis. It refers to an eyelid which is droopy. This may possibly cause a loss of vision, especially while reading, headaches, and eyebrow strain.