by David R. Jordan, M.D., F.A.C.S., F.R.C.S. (C)
- What is Essential Blepharospasm?
- How does Essential Blepharospasm present?
- What causes Essential Blepharospasm?
- Therapy for Essential Blepharospasm
- Surgery for Essential Blepharospasm
- Supportive Therapy for Essential Blepharospasm
- Apraxia of the Eyelids and Blepharospasm
- What Causes minor eyelid twitching (myokymia)?
- Surgery for Myokymia
- What is Hemifacial Spasm?
- How is Hemifacial Spasm Treated?
What is Essential Blepharospasm?
"Blepharo" comes from the Greek word for eyelids. Blepharospasm is a condition in which there is involuntary blinking of the eyelid that may at times be forceful and sustained (several seconds). Blepharospasm is a type of "Dystonia", a term used to describe "abnormal, involuntary, sustained muscle contractions and spasms". When the eyelid spasms occur, a temporary inability to see may result due to the forceful involuntary eyelid closure. Patients with Blepharospasm have normal eyes. The visual disturbance is due solely to the forced closure of the eyelids. In some individuals, other muscles of the face may be involved. With other facial spasms (perioral contractions, lip pursing, chin thrusting, tongue movements), the patients often have very unusual facial expressions that are uncontrollable. Dystonias may also occasionally occur elsewhere including the neck (torticollis, antecollis) or dystonic posturing of the limbs. Involuntary vocalization, such as grunting, frequent throat clearing, and respiratory noises as well as dysphagia and respiratory difficulties may develop. In advanced stages, patients with uncontrolled eyelid and facial spasms may become functionally blind, socially reclusive, and unable to work or care for themselves.
How does Essential Blepharospasm present?
The average age of onset is 56 years with females being more commonly affected than males by 3:1. Blepharospasm usually begins with a gradual increase in the blink rate that eventually progresses to forceful eyelid spasms frequently throughout the day. A fluctuating course characterized by remission and exacerbations is usual. It may be precipitated or aggravated by bright light, stress, fatigue, driving, reading, watching TV, and a variety of other activities. Sleep, relaxation training, walking and talking may improve the spasms. Some patients learn to avoid situations that aggravate the condition, while others develop certain behavioural techniques that involve using other facial muscles or acts of mental concentration to decrease the frequency and intensity of spasm. Examples include humming, singing, whistling yawning, coughing, mouth opening, nose pinching, chewing gum, talking continuously, rubbing the eyelids or applying pressure to other areas of the face, covering one eye, and solving puzzles or problems.
What causes Essential Blepharospasm?
Blepharoaspasm is thought to be secondary to an abnormal functioning of the "basal ganglia," an area of the brain which plays an important role in the control of fine motor movements. The exact problem in this area is unknown but a neurochemical imbalance is suspected. In some cases it may be familial disease with more than one family member affected. In other cases, blepharospasm may be secondary to drug therapy for other diseases (ex. medication for Parkinson's disease, major tranquilizers).
Therapy for Essential Blepharospasm
Blepharospasm can be treated with oral medication, injections of Botulinum toxin or surgery. Drug therapy is effective in fewer than 10% of patients and may only give partial relief. The response is unpredictable and side effects may outweigh the benefits. A variety of medications have been tried including antipsychotics, affective disorder agents, anxiolytic agents, sedatives, drugs for Parkinson's disease, muscle relaxants, etc.
Botulinum toxin is produced by the bacteria "Clostridium botulinum". Botulinum toxin interferes with acetylcholine release from peripheral motor nerve terminals, resulting in temporary paralysis of the injected muscles. Minute doses of botulinum toxin are injected around the eyelid and facial area with a fine needle. The effect usually occurs within the first few days and lasts an average of 3 to 4 months, at which time another injection is given. Muscle relaxants (orphenadrine, baclofen) have been useful in several patients as the effects of botulinum toxin start wearing off.
Long term follow up studies have shown botulinum toxin injection to be very safe and effective treatment with as many as 90% of patients obtaining significant relief of their spasms. Repeated treatment generally remains effective over a prolonged period in most patients. However, in some individuals, botulinum toxin injections may become less effective over time, possibly because of a resprouting of motor endplate receptors or the development of an antitoxin. Side effects are infrequent and transient. They include ptosis, blurred vision, double vision, ocular irritation and tearing. These side effects resolve spontaneously in a matter of days to weeks.
Surgery for Essential Blepharospasm
Surgical removal of the eyelid and brow squeezing muscles (myectomy) is available but generally reserved for those not responding to Botulinum toxin injections. The myectomy procedure for the upper lids involves a meticulous dissection and removal of the orbicularis, corrugator and procerus muscles through an eyebrow incision. In some, a lower eyelid myectomy is also required at a later date. The myectomy procedure requires hospitalization or 2 or 3 days. The healing process following a myectomy may take up to a year. In most cases, the patients are able to keep their eyes open immediately following the operation. However, considerable swelling, hematoma, lymphedema, and ecchymosis (varying greatly from patient to patient) may be present early in the postoperative period. Myectomy will improve the visual disability in approximately 90% of cases. Botulinum toxin injections may be required in some patients after the procedure for residual spasms.
The side effects of myectomy include numbness of the forehead, chronic lymphedema (lid swelling), exposure keratitis, ptosis, lid retraction, and ectropion. Most of these problems resolve with time. Only a small number of patients require touch-up procedures.
Supportive Therapy for Essential Blepharospasm
The psychologic impact of Essential Blepharospasm can be tremendous. Patients often feel their physicians do not believe their symptoms are uncontrolled and therefore may see several physicians before the proper diagnosis is made. It is not unusual for a patient to be initially seen by a physician who is unaware of this disease and refers them for psychiatric evaluation. They are generally greatly relieved when they are finally told they have a real disease and that some treatment is available. It is extremely important for patients to understand their disease process. Patients generally learn their own coping techniques which can be shared with others at support group meetings.
At present there is no cure for Essential Blepharospasm and related dystonias. Systemic medications help some patients. Debilitating spasms, however, continue in most cases, rendering patients functionally blind. Botulinum A toxin injection is the best temporary therapy and myectomy is the best long term therapy.
Apraxia of the Eyelids and Blepharospasm
Apraxia of eyelid opening is a condition that affects about 7% of Blepharospasm patients and rarely occurs on its own. The Blepharospasm patient with apraxia of lid opening will typically have lid spasms, squeezing the eyelids shut and then for several seconds to minutes after the spasms stop, the patient is unable to open the lids. The eyelids may then come open almost normally for a period of time and then without warning, slowly drop shut again, or be drawn shut by spasms. The apraxia of lid opening patient can be seen raising their brows and trying to open their eyelids as strongly as possible without any elevation of the eyelids. Apraxia is thought to be due to a problem in the neuro-circuitry for opening the eyelids, much like blepharospasm is a problem in the neuro-circuitry causing squeezing of the lids.
To make a diagnosis of apraxia of lid opening, all Blepharospasm or squeezing of the eyelids must be relieved. Botulinum toxin, myectomy or a combination thereof must completely relieve muscle squeezing before a diagnosis of apraxia of the opening can be confirmed. Blepharospasm patients with apraxia are treated by a limited myectomy in conjunction with tightening of the levator tendon (aponeurotic ptosis repair). By tightening the tendon of the muscle that raises the eyelids, patients can more effectively open their lids. By removing the squeezing muscles in the upper eyelids (limited myectomy), any residual squeezing that is not completely relieved by botulinum toxin is improved. Most patients with apraxia of lid opening can be improved with a combination of limited myectomy, ptosis repair and botulinum toxin. Unfortunately drugs have provided little or no improvement for this disorder.
What Causes minor eyelid twitching (myokymia)?
Myokymia is characterized by an involuntary, fine, contiguous muscle contraction involving a portion of the orbicularis oculi muscle or other facial muscles. It is often described as a twitch or flickering of the lid. Myokymia is most commonly unilateral, but bilateral cases have been reported. It tends to occur in young, healthy individuals and may last several hours to days. There may be a history of excessive physical exertion, fatigue, lack of sleep, stress, or excessive caffeine consumption. A localized orbicularis myokymia may also be seen after almost any type of eyelid surgery.
Myokymia generally requires no treatment as it commonly resolves spontaneously. Obtaining adequate sleep, reducing caffeine intake and decreasing stress are helpful. If the twitches persist on a daily basis for two months or longer, they can generally be abolished with a mild muscle relaxant or an injection of Botulinum toxin. Myokymia that begins with one eyelid but spreads to include other muscles of the face requires further investigation.
Surgery for Myokymia
Surgical removal of the eyelid and brow squeezing muscles (myectomy) is available but generally reserved for those not responding to Botulinum toxin injections. The myectomy procedure for the upper lids involves a meticulous dissection and removal of the orbicularis, corrugator and procerus muscles through an eyebrow incision. In some, a lower eyelid myectomy is also required at a later date. The myectomy procedure requires hospitalization for 2 to 3 days. The healing process following a myectomy may take up to one year. In most cases, the patients are able to keep their eyes open immediately following the operation. However, considerable swelling, hematoma, lymphedema, and ecchymosis (varying greatly from patient to patient) may be present early in the post operative period. Myectomy will improve the visual disability in approximately 90% of cases. Botulinum toxin injections may be required in some patients after the procedure for residual spasms.
The side effects of myectomy include numbness of the forehead, chronic lymphedema (lid swelling), exposure keratitis, ptosis, lid retraction, and ectropion, Most of these problems resolve with time. Only a small number of patients require touch-up procedures.
What is Hemifacial Spasm?
Hemifacial spasm is a benign, uncontrollable twitching of the muscles on one half (hemi-facial) of the face. It is a unilateral facial squeezing disorder unrelated to Essential Blepharospasm. Hemifacial spasms affect only those muscles innervated by the facial nerve. It usually begins around the eye with periodic twitching and spasms of the eyelids that close the eye partially or completely. It slowly spreads to involve other facial muscles on the same side as well as the superficial muscles of the neck. The condition does not cause pain but it may with time slowly cause weakness of the facial muscles involved. Hemifacial Spasm differs etiologically from Essential Blepharospasm. It is mostly caused by compression of the facial nerve by normal and abnormal vascular structures at the level of the brain stem, ex. a tortuous, distended basilar artery which may be stimulating the facial nerve as well as causing auditory dysfunction. Several different types of benign tumours (ex. dermoid), most commonly occurring outside of the brain but compressing the facial nerve, are the apparent causes in some cases. In other cases, neuro-imaging of the brain or even exploratory surgery cannot identify a cause. Although radiographic studies are not of value in investigating patients with Essential Blepharospasm, computed tomoghraphy (CT) with use of contrast agents should be performed to look for posterior fossa disease in those patients suspected of having Hemifacial Spasm.
How is Hemifacial Spasm Treated?
Hemifacial Spasm may be treated by medication, injection of botulinum toxin or surgery.
Drug therapy is usually only of benefit in mild cases and involves the administration of a muscle relaxant such as orphenadrine citrate (Norflex) or baclofen or the anti-convulsant clonazepam (Rivotril).
Botulinum toxin therapy is simple to perform and can be very effective in diminishing the spasms. Unlike Blepharospasms, Hemifacial Spasms seem to have a longer duration of effect with botulinim and may have 4 to 6 and, occasionally, up to 9 months of relief, The medication is injected into the periocular area as is with Blepharospasm. It may also be injected over the cheek area to try and decrease some of the lower facial muscle spasm. If the medication is given too close to the mouth, the patient will lose function of the perioral musculature and may have difficulty with talking, chewing food and facial expressions.
A neurosurgical microvascular decompression procedure (Janetta procedure) for Hemifacial Spasm may relieve the pressure of the artery on the nerve. Microvasular decompression is a non-destructive procedure which aims to treat the root cause of the disorder, rather than treating the symptoms. By separating the causative blood vessels from the nerve, symptoms of Hemifacial Spasm may be relieved. The operation requires general anaesthesia. A small incision is made behind the ear on the affected side and a small opening is made in the bone about the size of a quarter. The area in the brain stem where the 7th nerve is running is visualized with a microscope. The blood vessels are separated from the affected nerve or lateral brain stem. Small implants made of shredded Teflon are used to maintain the separation. The offending blood vessels rest on the Teflon instead of the nerve. The operation takes 2 to 3 hours and the average length of stay in the hospital is 72 hours. While it is generally successful, it is a neurological operation and serious complications are possible (meningitis, stroke, permanent facial paralysis, permanent hearing deficit, post-operative blood clots and even death).These are rare complications.
Complete cure for Hemifacial Spasm occurs in 80% of patients, 10% are markedly improved and 10% fail. Recurrence after successful operations is also infrequent with spasms recurring in only 4% to 6% of patients. Although the treatment of Hemifacial Spasm by microvascular decompression involves a neuro-surgical procedure, it is relatively safe procedure in skilled hands. Operative mortality is negligible and significant morbidity such as hearing loss, stroke, infection or other problems occur in less than 5% of patients. At this point, it remains a safe and well accepted surgical procedure, for those individuals not responding to drugs or botulinum toxin.