Blepharospasm is a condition in which the eyelids spasm, closing involuntarily, forcing the patient to blink abnormally. Blepharospasm is a form of focal dystonia or abnormal contractions of the eye muscles. Patients with blepharospasm have normal vision, but the disturbance interferes with visual perception and may, in severe cases, result in functional blindness.
Causes of Blepharospasm
While the underlying causes of blepharospasm are unknown, the disorder is associated with a dysfunction of the basal ganglion, the part of the brain that controls the muscles. In some cases, there seems to be a genetic component to blepharospasm since there is evidence of family history of this disorder or other types of dystonia. There are two types of blepharospasm, primary and secondary.
Symptoms of Blepharospasm
Blepharospasm is progressive, usually beginning with excessive blinking and eye irritation in the presence of stress factors such as bright lights, fatigue or emotional distress. Almost always present in both eyes, as the condition progresses symptoms occur more and more frequently, interfering with daily activities. Symptoms of blepharospasm do not occur during sleep and patients may experience a period of relief from symptoms upon waking. When the disorder becomes extreme, patients may be unable to open their eyes for hours at a time.
As times blepharospasm may occur with dystonia affecting the mouth and jaw, or oromandibular dystonia. In oromandibular dystonia, the patient involuntarily grimaces, clenches the jaw muscles and sticks out the tongue. When blepharospasm and oromandibular dystonia occur concurrently, the disorder is called Meige's syndrome. Patients with blepharospasm may experience continuing sensitivity to bright light and dry eyes.
Diagnosis of Blepharospasm
At present, there is no specific test for blepharospasm and, in most cases, laboratory results in patients with the disorder are normal. Blepharospasm is typically diagnosed on the basis of:
- Patient history
- Physical examination
- Neurological evaluation
Medical diagnosis is necessary to distinguish blepharospasm from other conditions affecting the eyelids, such as infection, allergy, and other conditions resulting in muscular weakness or contractions.