Adductor spasmodic dysphonia is a neurological voice disorder affecting the larynx, or voice box. This condition involves involuntary muscle spasms that cause the vocal folds to stiffen and slam closed, interfering with normal voice production and making speech difficult. It is a chronic condition, often requiring ongoing management.
Identifying the Symptoms
Individuals with adductor spasmodic dysphonia often experience a distinct vocal quality described as strained, tight, or strangled. Their speech may also sound as if it requires significant effort. This arises from the vocal folds spasming and forcibly closing too tightly, interrupting the smooth flow of air needed for sound production.
The spasms can cause speech to be choppy or broken, with words sometimes cutting off abruptly. Vowel sounds within words like “eat” or “olives” can be particularly challenging to produce smoothly. The disorder is task-specific; symptoms often worsen during connected speech, such as when talking on the phone. However, spasms may be absent or reduced during other vocal activities like laughing, crying, shouting, singing, or whispering.
Neurological Origins and Diagnosis
Adductor spasmodic dysphonia is a neurological disorder, classified as a focal dystonia (sustained involuntary muscle contractions). While the exact cause remains unknown, it is believed to originate from dysfunction within the brain’s basal ganglia. This region coordinates muscle movement, and abnormalities here are thought to send incorrect signals to the laryngeal muscles, causing the characteristic spasms.
Diagnosing this condition involves a comprehensive evaluation by a team of specialists. A speech-language pathologist assesses voice quality and production, often by listening to specific speech tasks. An otolaryngologist, or ENT doctor, conducts a visual examination of the vocal folds, often using flexible laryngoscopy (a lighted tube through the nose) to observe their movement during speech and rule out other causes. In some cases, laryngeal electromyography (LEMG) may confirm diagnosis by measuring the electrical activity of the voice box muscles.
Primary Treatment Approaches
The primary and most effective treatment for adductor spasmodic dysphonia is Botulinum toxin (Botox), injected directly into the affected laryngeal muscles. Botox works by temporarily blocking acetylcholine release at neuromuscular junctions, where nerves communicate with muscles. This action temporarily weakens the overactive adductor muscles, reducing involuntary spasms and allowing smoother, less effortful speech.
The procedure involves injecting a small, precise amount of Botox into one or both thyroarytenoid muscles, the main adductor muscles of the vocal folds. These injections are often guided by electromyography (EMG) to ensure accurate placement. Patients generally experience improvement within 48-72 hours, with benefits usually lasting approximately 3 to 4 months.
Common temporary side effects include a weak or breathy voice and occasional difficulty swallowing (dysphagia). These effects usually subside within a few days to a week as the Botox takes effect and the voice stabilizes. While Botox injections are the primary treatment, voice therapy serves as a complementary approach. A speech-language pathologist can help patients manage their voice, reduce compensatory strain, and improve breath support and overall vocal efficiency, though it is not a standalone cure.
Differentiating from Similar Voice Disorders
Distinguishing adductor spasmodic dysphonia from other voice disorders is important for accurate diagnosis and treatment. Abductor spasmodic dysphonia, a less common type, presents with an opposite effect: vocal folds spasm open instead of closed, leading to a weak, quiet, or breathy voice with voiceless breaks, particularly after unvoiced consonants.
Another condition that can be confused with adductor spasmodic dysphonia is muscle tension dysphonia (MTD). While MTD can also cause a strained or strangled voice, its origin is different; it results from overuse or misuse of laryngeal muscles rather than a neurological issue. A key differentiator is that adductor spasmodic dysphonia is task-specific, meaning symptoms vary depending on vocal activity, whereas muscle tension dysphonia typically presents more consistently across different types of vocalization.