Spasmodic Dysphonia is a chronic neurological condition that occurs due to excessive secretion of neurotransmitter chemicals by the brain called acetylcholine. These chemicals are normally secreted at the junction between the nerve endings and the muscle it stimulate during vocal cord opening and closure. The body normally controls how much chemical is needed and once the required movement is completed the chemical seize to be released.

In spasmodic dysphonia, the brain loose control of how much neurotransmitter is secreted in the vocal cords. This result into excessive contraction and spasm of the vocal cords that describe the symptoms of a spasmodic dysphonia. Other muscles of the body can be affected too causing excessive contraction of such muscle groups. This condition can sometimes be hereditary but usually presents from the 3rd decade of life onward.