Spasmodic dysphonia

Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm.^[1][2] This results in breaks or interruptions in the voice, often every few sentences, which can make a person difficult to understand.^[1] The person's voice may also sound strained or they may be nearly unable to speak.^[2] Onset is often gradual and the condition is lifelong.^[1]

The cause is unknown.^[1] Risk factors may include family history.^[1] Triggers may include an upper respiratory infection, injury to the larynx, overuse of the voice, and psychological stress.^[1] The underlying mechanism is believed to typically involve the central nervous system, specifically the basal ganglia.^[1] Diagnosis is typically made following examination by a team of healthcare providers.^[1] It is a type of focal dystonia.^[3]

While there is no cure, treatment may improve symptoms.^[1] Most commonly this involves injecting botulinum toxin into the affected muscles of the larynx.^[1] This generally results in improvement for a few months.^[1] Other measures include voice therapy, counselling, and amplification devices.^[1] If this is not effective, surgery may be considered; while evidence to support surgery is limited,^[1] some have recovered following surgery.^[4]

The disorder affects an estimated 2 per 100,000 people.^[1] Women are more commonly affected.^[1] Onset is typically between the ages of 30 and 50.^[1] Severity is variable between people.^[2] In some, work and social life are affected.^[2] Life expectancy is, however, normal.^[5]