What is Blepharospasm?
Blepharo means "eyelid". Spasm means "uncontrolled muscle contraction". The term blepharospasm ['blef-a-ro-spaz-m] can be applied to any abnormal blinking or eyelid tic or twitch resulting from any cause, ranging from dry eyes to Tourette's syndrome to tardive dyskinesia. The blepharospasm referred to here is officially called benign essential blepharospasm (BEB) to distinguish it from the less serious secondary blinking disorders. "Benign" indicates the condition is not life threatening, and "essential" is a medical term meaning "of unknown cause". It is both a cranial and a focal dystonia. Cranial refers to the head and focal indicates confinement to one part. The word dystonia describes abnormal involuntary sustained muscle contractions and spasms. Patients with blepharospasm have normal eyes. The visual disturbance is due solely to the forced closure of the eyelids.Blepharospasm should not be confused with:
- Ptosis - drooping of the eyelids caused by weakness or paralysis of a levator muscle of the upper eyelid.
- Blepharitis - an inflammatory condition of the lids due to infection or allergies.
- Hemifacial spasm - a non-dystonic condition involving various muscles on one side of the face, often including the eyelid, and caused by irritation of the facial nerve. The muscle contractions are more rapid and transient than those of blepharospasm, and the condition is always confined to one side.
The first part of Dr. Miller's video, "Diagnosis & Treatment with Botox of Patients with Benign Essential Blepharospasm & Related Disorders", shows different ways in which blepharospasm may manifest itself.
How Does Blepharospasm Begin?
Blepharospasm usually begins gradually with excessive blinking and/or eye irritation. In the early stages it may only occur with specific precipitating stressors, such as bright lights, fatigue, and emotional tension. As the condition progresses, it occurs frequently during the day. The spasms disappear in sleep, and some people find that after a good night's sleep, the spasms don't appear for several hours after waking. Concentrating on a specific task may reduce the frequency of the spasms. As the condition progresses, the spasms may intensify so that when they occur, the patient is functionally blind; and the eyelids may remain forcefully closed for several hours at a time.
What Causes Blepharospasm?
Blepharospasm is thought to be due to abnormal functioning of the basal ganglia which are situated at the base of the brain. The basal ganglia play a role in all coordinated movements. We still do not know what goes wrong in the basal ganglia. It may be there is a disturbance of various "messenger" chemicals involved in transmitting information from one nerve cell to another. In most people blepharospasm develops spontaneously with no known precipitating factor. However, it has been observed that the signs and symptoms of dry eye frequently precede and/or occur concomitantly with blepharospasm. It has been suggested that dry eye may trigger the onset of blepharospasm in susceptible persons. Infrequently, it may be a familial disease with more than one family member affected. Blepharospasm can occur with dystonia affecting the mouth and/or jaw (oromandibular dystonia, Meige syndrome). In such cases, spasms of the eyelids are accompanied by jaw clenching or mouth opening, grimacing, and tongue protrusion. Blepharospasm can be induced by drugs, such as those used to treat Parkinson's disease. When it is due to antiparkinsonian drugs, reducing the dose alleviates the problem.