Abductor Spasmodic Dysphonia (AB-SD)

A variant of spasmodic dysphonia in which the spasms pull the vocal cords apart, causing the voice to drop out or sound weak and breathy. Abductor spasmodic dysphonia (AB-SD) is an uncommon variant of spasmodic dysphonia, comprising only about 10% of the cases.

It is to be distinguished from adductor spasmodic dysphonia (AD-SD), a much more common variant in which the spasms push the vocal cords together.

Classic Variant AB-SD

In its classic variant, the abductory spasms of abductor spasmodic dysphonia are intermittent, each time pulling the vocal cords apart momentarily, so that a person’s voice drops out intermittently to a whisper or breathy sound. Hence, this classic variant of abductor spasmodic dysphonia is sometimes called intermittent whisper phonation.

Tonic Variant AB-SD

In its tonic variant, the abductory spasms are more constant and sustained than intermittent, so that instead of interrupting the person’s speech, the spasms produce a more constant breathy quality to the voice.

Other Variants

Occasionally, a person has both abductory and adductory spasms; this is called mixed AB-AD spasmodic dysphonia. For more about spasmodic dysphonia in general and the treatment options for it, see our main entry linked above.

Photo Examples

Visual Portfolio, Posts & Image Gallery for WordPress

AB-SD (1 of 4)

Prephonatory instant, with arytenoid cartilages involuntarily positioned apart. Mostly tonic position giving voice relatively constant breathiness.

AB-SD (2 of 4)

Phonatory blur, standard light. Again note the separation of the arytenoid cartilages posteriorly (upper end of the photo), and broad vibratory blur, both consistent with breathy voice.

AB-SD (3 of 4)

Occasionally, patient is able to bring posterior cords together for an instant of normal-sounding voice.

AB-SD (4 of 4)

An instant later, the vocal cords involuntarily separate due to an abductory spasm, dropping the voice again to a whispery quality.

Abductor Spasms, Worsened by Cognitive Loading

Visual Portfolio, Posts & Image Gallery for WordPress

Abductor spasmodic dysphonia patient (1 of 4)

Vocal cords in normal breathing position, in a person with abductor spasmodic dysphonia (SD). The next three photos show how the vocal cord spasms seen with SD can get worse when the person performs more cognitively loaded or involved tasks (that is, the person has to think more). This pattern is related to the widespread understanding that SD’s symptoms can be task-specific.

Limited abductor spasms (2 of 4)

When making voice with guttural vocal fry or sustained creaky falsetto, this person is able to keep the vocal cords together, at least part of the time.

Increased abductor spasms (3 of 4)

When the person tries to sustain a sung tone (slightly more cognitively loaded), the vocal cords involuntarily separate, producing a very breathy voice.

Even greater abductor spasms (4 of 4)

When the person speaks (even more cognitively loaded), the vocal cords separate even further, and the voice’s breathiness is pronounced.

Share this article

AB-SD YouTube Thumbnail
Play Video about AB-SD YouTube Thumbnail

Vocal Cords Spasm Apart (AB-SD)

Syllables or words drop away to a whisper when a person is afflicted by the less common variant of a neurological disorder called AB-ductory spasmodic dysphonia (AB-SD).

Due to its effect on speech, it is sometimes called “intermittent whisper dysphonia.” In this video you will find a description of the disorder, its treatment with botox, and how to assess for proper dosage and placement of this medication.

AB-SD Youtube thumbnail
Play Video about AB-SD Youtube thumbnail

Voice Drops or Sounds Breathless? AB-SD Phenomenology 

Notify of

Inline Feedbacks
View all comments
Click to see all comments.x