Spasmodic dysphonia is an idiopathic dystonia that affects the muscles of the larynx during specific movements of the larynx. As a localized form of movement disorder Focal dystonias Dystonias are sustained involuntary muscle contractions of antagonistic muscle groups in the same body part, leading to sustained abnormal posturing or jerky, twisting, intermittent spasms that... read more , spasmodic dysphonia has an onset between ages 30 and 50 years, and about 60% of patients are women.
There are 3 main forms:
Adductor spasmodic dysphonia
Abductor spasmodic dysphonia
Mixed spasmodic dysphonia
In adductor spasmodic dysphonia, a patient's voice sounds squeezed, effortful, or strained due to uncontrolled closure of the vocal folds during speech. These spasmodic episodes usually occur when vowel sounds are being formed, particularly at the beginning of words.
In abductor spasmodic dysphonia, which is less common, sudden interruptions of sound caused by uncontrolled opening of the vocal cords are accompanied by an audible escape of air during connected speech.
Those with mixed spasmodic dysphonia may display features of both adductor and abductor spasmodic dysphonia to varying degrees and at different times.
(See also Overview of Laryngeal Disorders Overview of Laryngeal Disorders The larynx contains the vocal cords and serves as the opening to the tracheobronchial tree. Laryngeal disorders include Benign laryngeal tumors Contact ulcers Laryngitis Laryngoceles read more .)
Treatment of Spasmodic Dysphonia
Botulinum toxin injection
Selective laryngeal nerve section and reinnervation surgery
For adductor spasmodic dysphonia, injection of botulinum toxin (BoNT) into vocal adductors has become the standard of care, with targeting injections achieving a normal voice in approximately 70% of patients for up to 3 months. Because the effect of BoNT is temporary, injections must be repeated to maintain the improvement. Selective laryngeal nerve section with reinnervation surgery is also an option in certain centers. Laryngeal nerve section without reinnervation has been shown to result in synkinesis and is not the preferred approach to this condition.
For abductor spasmodic dysphonia, no known treatment permanently alleviates the disorder, but temporary improvement has been achieved with botulinum toxin delivered to the posterior cricoarytenoid muscle (sole vocal abductor, 1 Treatment references Spasmodic dysphonia (vocal cord spasms) is intermittent spasm of laryngeal muscles that causes an abnormal voice. Spasmodic dysphonia is an idiopathic dystonia that affects the muscles of the... read more , 2 Treatment references Spasmodic dysphonia (vocal cord spasms) is intermittent spasm of laryngeal muscles that causes an abnormal voice. Spasmodic dysphonia is an idiopathic dystonia that affects the muscles of the... read more ). Surgical medialization (shifting toward the midline by inserting an adjustable spacer laterally) of both vocal cords has some benefit for some patients (3 Treatment references Spasmodic dysphonia (vocal cord spasms) is intermittent spasm of laryngeal muscles that causes an abnormal voice. Spasmodic dysphonia is an idiopathic dystonia that affects the muscles of the... read more ).
Treatment references
Mor N, Simonyan K, Blitzer A: Central voice production and pathophysiology of spasmodic dysphonia. Laryngoscope 128(1):177-183, 2018. doi:10.1002/lary.26655
Dharia I, Bielamowicz S: Unilateral versus bilateral botulinum toxin injections in adductor spasmodic dysphonia in a large cohort [published online ahead of print, 2019 Dec 14]. Laryngoscope 10.1002/lary.28457, 2019. doi:10.1002/lary.28457
Dewan K, Berke GS: Bilateral vocal fold medialization: a treatment for abductor spasmodic dysphonia. J Voice 33(1):45-48, 2019. doi:10.1016/j.jvoice.2017.09.027
