Speech intelligibility in severe adductor spasmodic dysphonia

Area of Science:

• Neurology
• Speech-Language Pathology
• Otolaryngology

Background:

• Adductor spasmodic dysphonia (ADSD) is a neurological voice disorder characterized by involuntary vocal fold closure, leading to impaired speech.
• Botulinum toxin (Botox) injections are a common treatment for ADSD, aiming to reduce muscle hypercontraction and improve voice quality.

Purpose of the Study:

• To quantitatively assess the impact of Botox injections on speech intelligibility in individuals with severe ADSD.
• To compare speech intelligibility in ADSD patients before and after treatment with healthy controls.

Main Methods:

• Speech samples from 10 severe ADSD patients (pre- and post-Botox) and 10 healthy controls were collected.
• Thirty phrases from each speaker were used in a listening experiment with 30 naive student listeners.
• Listener responses were scored for word identification accuracy to determine intelligibility percentages.

Main Results:

• Speakers with ADSD showed significantly improved intelligibility after Botox injection compared to before treatment.
• Healthy speakers were consistently more intelligible than ADSD speakers in both pre- and post-Botox conditions.
• Botox treatment enhanced intelligibility but did not restore it to the level of non-impaired speakers.

Conclusions:

• Severe ADSD significantly affects speech intelligibility.
• Botox injections are an effective treatment for improving speech intelligibility in ADSD.
• While beneficial, Botox treatment does not fully normalize speech intelligibility to that of healthy individuals.