Spasmodic Dysphonia.

Spasmodic dysphonia (SD) is a rare focal laryngeal dystonia. It is characterized by task-specific voice dysfluency resulting from selective intrinsic laryngeal musculature hyperfunction. Symptoms may be attenuated by a sensory trick. Although SD can be seen at times in generalized dystonia syndromes, it is typically a sporadic phenomenon. Involvement of the laryngeal adductor muscles is more common than abductor muscles. The standard treatment of this disorder is with botulinum toxin injection, usually electromyography-guided, which must be repeated periodically as the toxin wears off. A number of non-reversible surgical procedures have also been described to mitigate the symptoms. Other treatment modalities are under investigation, including implantable electrical stimulation devices and deep brain stimulation.