Spasmodic Dysphonia (SD)

A non-life-threatening neurological disorder in which the muscles of the larynx involuntarily spasm and interfere with the voice. Spasmodic dysphonia is a focal dystonia, in this case involving the larynx—i.e., laryngeal dystonia. Laryngeal dystonia typically affects the voice, but can occasionally also affect breathing (respiratory dystonia). The term spasmodic dysphonia refers specifically to voice-affecting laryngeal dystonia.

Adductor vs. abductor:

There are two main variants of spasmodic dysphonia (SD). In the first variant, adductor SD (AD-SD), the vocal cords are pressed together excessively, intermittently cutting off words or giving the voice a constant strangled quality; this variant comprises 90% of the cases of SD. In the second variant, abductor SD (AB-SD), the vocal cords are abruptly and momentarily pulled apart while talking, causing the voice to drop out completely or down to a whispery, breathy sound. There are some cases in which a person has both of these variants: this is called mixed AB-AD SD.

Classic vs. tonic:

Another distinction that can be made is between classic variant and tonic variant cases of SD. In classic variant SD, the spasms cause phonatory arrests—that is, while the person is speaking, intermittent words or syllables are choked off (with AD-SD) or drop out (with AB-SD). In tonic variant SD, the spasms are more continuously sustained, so that the voice continuously sounds either strained (with AD-SD) or breathy (with AB-SD), but without any actual phonatory arrests. Because the presence of phonatory arrests is the symptom most often associated with SD, tonic variant SD goes undiagnosed or misdiagnosed far more frequently than does classic variant SD.

Treatment for spasmodic dysphonia:

There is no definitive “cure” for SD, but for most patients, periodic injections of Botox™ into the muscles of the larynx help a great deal, if there is optimal dosage and placement. These injections relax the malfunctioning muscles of the larynx, thereby minimizing the spasms and their impact on the voice. The effect of an injection typically lasts a few months, and then another injection is needed. For those having difficulty getting good results with Botox™ therapy, see our video below “Spasmodic Dysphonia: When Botox Disappoints.”

The leading surgical treatment currently offered for SD, Selective Laryngeal Adductor Denervation-Reinnervation, can be an option for individuals with the AD-SD variant. However, no treatment for SD works satisfactorily for all. The history of each of the several surgical treatments for SD always includes some failures.

Speech therapy is another treatment sometimes suggested for SD. While there are strong and even passionate individual proponents of speech therapy, the consensus view is that speech therapy is not expected to substantially improve the voice’s capabilities or reduce spasms other than perhaps in the therapy room1. A brief course of speech therapy can be very helpful for patient education and perhaps a search for sensory tricks. Much confusion surrounds this subject, because individuals who have a nonorganic voice disorder can be mistakenly diagnosed with SD, and nonorganic voice disorders are routinely “cured” with speech therapy alone.


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Spasmodic Dysphonia: A Peculiar Voice Disorder
Dr. Robert Bastian reviews the various types and subtypes of spasmodic dysphonia (SD). Numerous voice examples are included, along with video of the vocal folds. SD is a rare neurological disorder caused by laryngeal dystonia, and it interferes with the smooth functioning of the voice. Tiny spasms of the vocal folds may cause the voice to catch or cut out, strain or squeeze away, and sometimes to drop momentarily to a whisper.
Spasmodic Dysphonia: When Botox Disappoints
In this video, Dr. Bastian discusses common problems with Botox treatment for spasmodic dysphonia (SD) and offers clear, practical advice to increase the effectiveness of these treatments.
2014 NSDA 25th Anniversary Symposium
In this video, Dr. Bastian leads a panel discussion on Spasmodic Dysphonia.

  1. Ludlow CL. Treatment for spasmodic dysphonia: limitations of current approaches. Curr Opin Otolaryngol Head Neck Surg. 2009; 17(3): 160–165. 

  2. Ludlow CL. Treatment for spasmodic dysphonia: limitations of current approaches. Curr Opin Otolaryngol Head Neck Surg. 2009; 17(3): 160–165.