2004 Volume 16 Issue 2 Pages 67-73
Botulinum toxin (BT) injection into thyroarytenoid (TA) muscles is a very effective treatment for Spasmodic Dysphonia (SD). In this paper, we report on our experience of 1486 injections for 260 cases of SD in Japan over a 15-year period (1989-Jan. 2004). We made use of Type A neurotoxic BT, which blocks the release of acetylcholine at neuromuscular junctions, resulting in reversible paralysis of the TA muscles.
We can identify TA muscles by using an injection needle as an electrode for electromyography (EMG). Several tasks (phonation, breath-holding, etc.) are necessary to identify TA muscles with EMG signals. There are basically four options for injection quantity : 2.5 units unilaterally, 2.5 bilaterally (5.0 in total), 5.0 unilaterally, and 5.0 bilaterally (10.0 in total).
A BT injection for SD is effective for 17.3 weeks on average. The main side effects are breathy hoarseness and misdiglutition, which may last for less than two weeks. We have not observed antibody production. The possibility of antibody production is thought to be very low with such small quantities (2.5-10.0 units per injection) given over rather long intervals (once in 3-4 months).
It is our hope that BT injections will be authorized by the medical insurance system in Japan, and that more institutes will perform this effective treatment for the benefit of SD patients.
