Published online by Cambridge University Press: 28 July 2009
Introduction
Spasmodic dysphonia is a focal dystonia characterized by task-specific, action-induced spasm of the vocal cords. It adversely affects the patient's ability to communicate. It can occur independently, as part of cranial dystonia (Meige's syndrome), or in other disorders such as in tardive dyskinesia.
Clinical features
There are three types of spasmodic dysphonia: the adductor type, the abductor type, and the mixed type.
Adductor spasmodic dysphonia (ADSD) is characterized by a strained-strangled voice quality and intermittent voice stoppage or breaks due to overadduction of the vocal folds, resulting in a staccato-like voice.
Abductor spasmodic dysphonia (ABSD) is characterized by intermittent breathy breaks, associated with prolonged abduction folds during voiceless consonants in speech.
Patients with the mixed type have presentations of both.
Symptoms of spasmodic dysphonia begin gradually over several months to years. The condition typically affects patients in their mid 40s and is more common in women (Adler et al., 1997; Schweinfurth et al., 2002).
Spasmodic dysphonia may coexist with vocal tremor. Patients with ADSD show evidence of phonatory breaks during vocalization. The vocal breaks typically occur during phonation associated with voiced speech sounds (Sapienza et al., 2000).
Stress commonly exacerbates speech symptoms; while they are absent during laughing, throat clearing, coughing, whispering, humming, and falsetto speech productions (Aronson et al., 1968). The voice tends to improve when the patient is emotional.
Treatment options for ADSD
The efficacy of botulinum toxin in the treatment of spasmodic dysphonia has been proven in a double-blind study (Truong et al., 1991).
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