Diffusion of Aniline Blue Injected into Thyroarytenoid Muscle

Abstract

Objective: Intralaryngeal injection of botulinum toxin into the thyroarytenoid (TA) muscle is one of the methods for the treatment of laryngeal focal dystonia. The side effects and the modification of the laryngeal configuration are probably due to the diffusion of the botulin toxin to nearby structures. Aim: Analyze the diffusion of aniline blue (liquid substance) injected into the TA to the adjacent intrinsic laryngeal muscles.

Method: Study Design: Experimental. Eighteen excised cadaveric larynges were analyzed after injection of aniline blue (0.2 mL) into the TA, using the intralaryngeal technique. After fixation by formaldehyde and decalcification using nitric acid, the larynges were sectioned in the coronal plane in 4 slices and the intrinsic muscles analyzed.

Results: The aniline blue spread to the lateral cricoarytenoid muscle, the cricothyroid muscle and the posterior cricoarytenoid muscle 94.3%, 42.9%, and 8.6%, respectively. Gender, height, and width of the TA had no effect on the likelihood of diffusion to any of the muscles.

Conclusion: The present study showed that, based on the methodology proposed, the diffusion of a solution injected into the TA occurs in almost all cases toward the CAL muscle. The CT muscle was affected in half of the cases. Although rarely, it can also achieve the PCA muscle.