This operation is designed for patients with isolated adductor-type spasmodic dysphonia. A major drawback of this therapy is that the effect is only temporary, lasting 3 to 6 months, and requires frequent injections. The merit of this operation is the long-term effects, with the success rate of 92% with follow-up periods of 2–5 years.

Some papers in the early stage have reported poor long-term results, although their reports did not discuss any possible causes for the failure. The success of surgery depends entirely on the proper fixation of the separated thyroid cartilage, and inadequate fixation results in poor long-term effects. Differentiation of adductor type from abductor type and from mixed type spasmodic dysphonia is also challenging. Furthermore, laryngeal tremor can be difficult to distinguish from spasmodic dysphonia and can be found as an isolated entity or can accompany spasmodic dysphonia (“tremor-type spasmodic dysphonia”). Patient selection is therefore likely the largest hurdle.

In the United States, Botox remains the standard of care. Many surgical procedures (recurrent laryngeal nerve section, thyroarytenoid myectomy, thyroarytenoid diathermy) designed to treat adductor-type spasmodic dysphonia do not have proven long-term benefit.

The success of the procedure depends on whether or not the incised cartilage edges are held apart at the precise spot for the best vocal output with no excessive effort of speech, and whether or not they remain adequately separated over time.

An appropriate device for maintaining the separation, such as the titanium bridge ( Fig. 20.1 ) developed by Isshiki, is essential. In the laboratory, a piece of cartilage from the superior rim of the thyroid ala may be used instead.

Inadequate fixation of the separated cartilage results in a poor long-term outcome.

Silicone is not a suitable material for this procedure because it is too soft to make the fixation stable.

Careless management of the inner perichondrium at the anterior commissure level will cause a mucosal perforation because the mucosa just above the anterior commissure is very thin, risking infection of the wound.

Separating the cartilage and the inner perichondrium too much at the anterior commissure level makes the vocal folds shorter, resulting in a lower-pitched voice.