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.