http://www.dysphonia.org/faq.asp?nav=spa#spa
National Spasmodic Dysphonia Association
Spasmodic dysphonia (SD), a focal form of dystonia, is a neurological voice disorder that involves involuntary "spasms" of the vocal cords causing interruptions of speech and affecting the voice quality. Find out more information about this disorder with a list of the most frequently asked questions.