Spasmodic Dysphonia (Laryngeal Dystonia)

What causes spasmodic dysphonia

Spasmodic dysphonia is a dystonia: a disorder of the brain's movement control circuits (involving the basal ganglia, cerebellum and sensorimotor cortex) that causes inappropriate muscle contractions. The vocal cords themselves look normal at rest. The exact cause is unknown. Factors that may play a role:

• genetic susceptibility; some people have family members with other forms of dystonia or tremor
• a preceding upper respiratory infection, injury or period of heavy voice use or stress, in some cases
• coexisting cervical dystonia, blepharospasm or essential tremor

It is not caused by psychological problems, although stress can worsen symptoms.

Types and symptoms

Other features:

• symptoms are task-specific: often normal or near normal when laughing, crying, whispering, shouting or singing
• worse with stress, fatigue and phone conversations
• often improves briefly after alcohol (a reported clue)
• vocal tremor in some people
• increased effort and fatigue from speaking

Diagnosis

There is no single test. A team, usually an ENT doctor (laryngologist) and a speech-language pathologist, makes the diagnosis by:

• listening to speech samples with sentences designed to trigger each type
• flexible laryngoscopy: a thin camera through the nose to watch the vocal cords during speech
• ruling out other conditions

Conditions that mimic spasmodic dysphonia

• Muscle tension dysphonia: excessive tension of voice muscles from overuse or habits; usually responds well to voice therapy
• Vocal cord paralysis: breathy weak voice, visible on laryngoscopy
• vocal cord nodules, polyps or laryngitis
• essential voice tremor: rhythmic shaking of the voice
• neurological conditions such as Parkinson's disease or ALS
• laryngeal cancer in persistent hoarseness

Treatment

Botulinum toxin injections

The standard treatment. Small doses of botulinum toxin are injected into the affected laryngeal muscles, usually through the neck under electromyography guidance. Effects:

• improvement begins in a few days and lasts about 3 to 4 months
• a temporary breathy or weak voice, and mild swallowing difficulty with liquids, can occur in the first 1 to 2 weeks
• repeat injections are needed
• very effective for adductor SD; less consistently effective for abductor SD

Voice therapy

Speech therapy cannot cure SD but can help reduce strain, improve breath support and make injections work better. It is the main treatment for muscle tension dysphonia, which can coexist.

Surgery

For selected people who do not want ongoing injections:

• selective laryngeal adductor denervation-reinnervation (SLAD-R)
• thyroarytenoid myectomy
• type 2 thyroplasty (widening the space between the vocal cords), used more in some countries

Other options

Oral medicines used for dystonia (such as anticholinergics or clonazepam) have limited benefit. Research continues into brain stimulation and other treatments.

Living with spasmodic dysphonia

• schedule demanding speaking tasks when injection benefit is greatest
• use voice amplifiers or text-based communication when needed
• tell colleagues and family about the condition
• join support groups such as the National Spasmodic Dysphonia Association

Frequently asked questions

What is spasmodic dysphonia?

Spasmodic dysphonia, or laryngeal dystonia, is a chronic neurological voice disorder in which the muscles of the voice box spasm involuntarily during speech, causing a strained, choked or breathy voice with breaks. It originates in the brain, not the vocal cords.

What causes spasmodic dysphonia?

It is a type of focal dystonia caused by abnormal signaling in the brain's movement control networks. The exact cause is unknown. Genetics may play a role, and it sometimes begins after an illness or stressful period. It is not caused by anxiety.

Is spasmodic dysphonia curable?

There is no cure, but treatment works well for most people. Botox injections every 3 to 4 months improve the voice in most cases of adductor spasmodic dysphonia. Surgery can provide longer-lasting improvement for selected patients.

How does Botox help spasmodic dysphonia?

Botulinum toxin weakens the overactive voice box muscles, reducing spasms. Improvement begins within days and lasts about 3 to 4 months. A breathy voice or mild swallowing difficulty for 1 to 2 weeks afterward is a common, temporary side effect.

How is spasmodic dysphonia different from muscle tension dysphonia?

Both cause strained voice, but muscle tension dysphonia results from excess muscle tension and habits and usually responds to voice therapy. Spasmodic dysphonia is a neurological condition with involuntary spasms that are often task-specific and usually needs Botox injections.