is a voice disorder caused by involuntary movements of one or more muscles of the larynx or voice box. Individuals who have spasmodic dysphonia may have occasional difficulty saying a word or two or they may experience sufficient difficulty to interfere with communication. Spasmodic dysphonia causes the voice to break or to have a tight, strained or strangled quality. While the cause of spasmodic dysphonia is unknown, most cases are believed to be neurogenic (having to do with the nervous system) in nature. Some cases occur along with movement disorders and some may be inherited. While anyone can be affected, spasmodic dysphonia more often affects women and begins in those between the ages of 30 and 50.
There are three different types of spasmodic dysphonia:
Adductor spasmodic dysphonia (causes the vocal cords to slam together and stiffen)
Abductor spasmodic dysphonia (causes the vocal cords to open)
Mixed spasmodic dysphonia (causes the vocal cords to open and close) Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.