Definition
This is a bilateral condition (affects both sides) in which episodic spasm of the eyelids occurs.
Incidence/Age
Blepharospasm is relatively uncommon, generally with an onset between the ages of 45-60 years.
Anatomy and Physiology
The spasm occurs in the orbicularis oculi muscle, which is present in and around the eyelids. Normal contraction of this muscle is responsible for blinking and eyelid closure.
Causes
The exact cause of blepharospasm is unknown, but it is thought to be due to an abnormality in the mid-brain. Some patients with known diseases in this region of the brain, eg, Parkinsons disease, often have a degree of blepharospasm.
Symptoms and Signs
Intermittent excessive blinking is usually the first symptom. The blinking gradually intensifies, insidiously becoming an involuntary spasm of the eyelids. Although only one side may be initially affected, it later becomes bilateral, occasionally producing impairment of vision that can interfere with daily activities. Spasms are generally worse later in the day and often when patients are emotionally stressed.
Complications of Disorder
Blepharospasm can occasionally be very debilitating. With disease progression about 10% of sufferers become functionally blind due to difficulty with eye opening. Many people severely affected withdraw from various activities and social contact.
Tests
Blepharospasm is a clinical diagnosis made from a history and examination. Important bilateral conditions causing similar eyelid spasm to exclude are habit spasm (tic) and reflex blepharospasm due to eye surface problems, eg, dry eyes or referred nerve pain, eg, facial neuralgia.
Investigations are occasionally indicated when the diagnosis is unclear, in particular for one-sided spasms when the possible causes are more numerous.
Treatment
A variety of antipsychotic, antidepressant and muscle relaxant medications have been tried with little success. The current treatment of choice for blepharospasm involves injections of botulinum type A toxin into the orbicularis oculi muscle. This chemical causes a temporary paralysis of the muscle, which often provides relief from the spasms for 2-3 months. Repeated injections are therefore necessary, but these can be performed with minimum discomfort as an out patient procedure.
Botulinum toxin treatment for blepharospasm is very safe but careful dose selection and placement of the injections is required to avoid transient complications such as droopy upper lids (ptosis) and double vision (diplopia).
Rarely a surgical procedure is required for those people not helped by botulinum toxin treatment. This involves the meticulous stripping of the orbicularis muscle, which is removed via multiple small skin cuts under general anaesthetic.
Outcome/Prognosis
Although no ideal treatment exists, the majority of people have their eyelid spasms reasonably controlled using repeated botulinum toxin injections. However a small number of people develop antibodies to the chemical which subsequently becomes less effective.
source:www.privatehealth.co.uk
Last Editorial Review: 18/1/2010
