Excessive involuntary blinking (blepharospasm)
Benign essential blepharospasm is the term used for any abnormal blinking or eyelid twitching, the cause of which is unknown. It is a type of facial dystonia, a term which means abnormal involuntary sustained muscle contractions and spasms. In order to diagnose blepharospasm all other causes of eyelid twitching eg blepharitis, dry eye etc need to be ruled out.
Initially the condition usually begins gradually with excessive blinking or eyelid twitching. This tends to affect both eyes, but one side may be worse than the other. Symptoms may be brought on or made worse by triggers such as bright lights, stress and fatigue. Spasms can intensify as the disease progresses such that people can have increasing difficulties holding their eyes open, the eyelids remaining forcefully closed ("apraxia" of eyelid opening) for several hours at a time in the worse cases.
Treatment options for Blepharospasm
Many different medications eg: trihexyphenidyl, clonazepam have been tried over the years with limited success. Few have been subjected to rigorous clinical trials and, therefore, although treatments are often individualized they are to a degree a matter of trial an error. Expert advice and supervision is required as some agents have potential side-effects and even dependency.
This is the most effective and best tolerated treatment for blepharospasm and is usually tried first. Botulinum toxin is a purified protein, produced by the bacterium Clostridium botulinum, which works as a neurotoxin (see Botulinum Toxin). It works by preventing nerve cell signals from reaching muscles. When injected in tiny amounts around the eyelids and eyebrows it can be useful at reducing that activity of muscles in spasm, whilst not affecting other muscles which are working normally.
We undertake a "Disability Index Questionnaire" prior to starting Botulinum toxin treatment in order to establish severity of the blepharospasm and it is useful for monitoring treatment success. The injections are given as an out-patient and tend to work for a few months and then need to be repeated on a regular basis.
Some patients may be helped from therapies to reduce stress if appropriate. Dark glasses are often useful and occasionally distraction techniques may reduce spasms. Many sufferers will benefit from the support offered by groups such as the dystonia society (www.dystonia.org.uk)
As a last resort in cases where other less invasive treatments are ineffective some patients may be helped by surgery. This either involves removal of some or all of the muscles responsible for the eyelid spasm (orbicularis myectomy) or using a suspension material to connect the eyelids to the forehead frontalis muscle (the normal function of the frontalis muscle is to raise the eyebrows).