Spasmodic dysphonia (SD), sometimes known as laryngeal dystonia, is a neurological voice disorder in which the vocal cords contract involuntarily. Speech and voice are interrupted during the spasms. Originally described by L. Traube in 1871, according to the National Spasmodic Dysphonia Association, this disorder falls in the family of focal dystonias. The term dystonia describes excessive muscle contractions and movements in the body. Dystonias may be the result of a dysfunction in the basal ganglia, an area of the brain that helps coordinate movement, according to the Spasmodic Dysphonia Association. In cases where SD runs in families, a genetic factor has been identified, according to National Institute on Deafness and Other Communication Disorders. The disorder typically begins in individuals age 30 to 50 and it appears more often in women than in men, the American Speech-Language Hearing Association says. SD has three basic types.
Adductor Spasmodic Dysphonia
Adductor SD involves sporadic and powerful closings of the vocal cords during vowel production. With this strong contraction of the vocal cords, airflow stops. There can be no voicing without airflow because air is what sets the vocal cords vibrating. Words may stop suddenly, causing the speaker to sound strained, with starts and stops similar to stuttering. Spasms do not occur during laughing, singing, whispering, speaking in a high pitch or speaking on inhalation, according to the National Spasmodic Dysphonia Association and the American Speech-Language Hearing Association.
Abductor Spasmodic Dysphonia
Abductor SD involves spasms that pull the vocal cords open. Vocal cords cannot vibrate in that position, so the voice sounds breathy and weak. As with adductor SD, symptoms lessen with coughing, laughing, singing and other vocalizations not related to talking. Stress seems to exacerbate symptoms of abductor and adductor SD.
Mixed Spasmodic Dysphonia
Mixed SD involves adductor and abductor spasms. The National Spasmodic Dysphonia Association reports two other subtypes of mixed SD. In one subtype, SD is combined with a voice tremor. In another subtype, a severe primary voice tremor results in spasms that prohibit voicing during the tremor. Currently, SD has no cure. A team of professionals evaluates patients with SD symptoms. Otolaryngologists examine the vocal cords to look for other causes. Speech-language pathologists evaluate voice quality and loudness. Neurologists evaluate the patient for indications of other neuromuscular disorders. Current treatment often includes repeat injections of botulinum toxin into one or both vocal cords, according to the American Speech-Language Hearing Association. The toxin causes laryngeal muscles to relax, allowing smoother voice production.
