Diffusion of aniline blue injected into the thyroarytenoid muscle as a proxy for botulinum toxin injection: an experimental study in cadaver larynges

Endolaryngeal injection of botulinum toxin into the thyroarytenoid (TA) muscle is one of the methods for treatment of focal laryngeal dystonia. However, after treatment, there is variation in laryngeal configuration as well as the side effects reported by patients. As a consequence of the functional variability of results, it was hypothesized that botulinum toxin diffuses beyond the limits of the muscle into which it is injected. OBJECTIVES: After injection of botulinum toxin into the TA muscle for the treatment of focal laryngeal dystonia, patients differ in terms of laryngeal configuration and side effects. We hypothesized that this toxin diffuses from the target muscle to adjacent muscles. METHOD: The TA muscles of 18 cadaver larynges were injected with aniline blue (0.2 mL). After fixation in formaldehyde and nitric acid decalcification, the larynges were sectioned in the coronal plane and the intrinsic muscles were analyzed. RESULTS: We found diffusion of aniline blue to the lateral cricoarytenoid muscle, cricothyroid muscle, and posterior cricoarytenoid muscle in 94.3%, 42.9%, and 8.6% of the cases, respectively. In terms of the degree of diffusion to adjacent muscles, we found no differences related to the size (height and width) of the TA muscle or to gender. CONCLUSIONS: Our findings suggest that diffusion of botulinum toxin from its injection site in the TA muscle to the lateral cricoarytenoid muscle is likely in most cases. On the other hand, diffusion to the cricothyroid muscle occurs in approximately half of cases and diffusion to the posterior cricoarytenoid muscle occurs in very few cases...

Histological analysis of autologous fascia graft implantation into the rabbit voice muscle / Análise histológica em músculo vocal de coelhos submetidos a implante de fáscia lata autóloga

The ideal approach for the treatment of glottal insufficiency remains a challenge for laryngologists. AIM: This experimental study assessed the histological changes and fibrosis caused by autologous fascia lata grafts into the rabbit voice muscle. STUDY DESIGN: A clinical and experimental study. METHODS: A 0.2 × 0.2 cm fragment of autologous fascia lata was grafted into the right voice muscle of 14 adult rabbits. Animals were euthanized 30 or 60 days post-procedure and histology of the excised vocal folds was carried out. RESULTS: No extensive edema, necrosis or foreign body-type reaction was observed at any time. No significant inflammatory reaction or fibrosis was seen at 30 or 60 days. CONCLUSION: The presence of fascia lata in the rabbit voice muscle had no significant influence on inflammation, and does not increase fibrosis. Rabbit voice muscle shows good tolerance to fascia lata grafting.

A apropriada abordagem no tratamento da insuficiência glótica causada por paralisa, cicatriz e atrofia de prega vocal é um desafio ao laringologista. OBJETIVO: O presente estudo avaliou as alterações histológicas e fibrose desencadeadas pelo enxerto autólogo de fáscia lata no músculo vocalde coelhos. FORMA DE ESTUDO: Clínico e Experimental. MATERIAL E MÉTODO: Foi realizado um estudo experimental com 14 coelhos adultos que foram submetidos a implante de fáscia lata autóloga medindo 0,2 x 0,2cm, no músculo vocal direito. Os animais foram sacrificados após 30 e 60 dias do procedimento, suas laringes removidas e submetidas a estudo histológico. RESULTADOS: Não foi observado edema extenso, área de necrose ou reação inflamatória do tipo corpo estranho. A reação inflamatória observada após 30 e 60 dias foi leve, bem como a fibrose desencadeada. CONCLUSÃO: A presença de fáscia lata autóloga no músculo vocal de coelho não desencadeou fibrose e resposta inflamatória significativa.

Endolaryngeal neurofibroma

Neurofibromatosis is a benign neurogenic tumor, originating from Schwann cells of the nerve sheath. This tumor forms a round, white mass on the course of the involved nerve. It occurs sporadically or in association with von Recklinghausen's disease. Laryngeal involvement is a rare occasion that affects women more than men [F/M ratio 3:2]. The most common symptoms are hoarseness, dyspnea and dysphagia. The most common sites of origin are arytenoids and aryepiglottic folds. Because of benign nature of this tumor, conservative surgery is recommended as the management of choice. Only few cases of laryngeal involvement have been reported in literature and this article presents two cases of laryngeal neurofibroma with brief review of literatures. Both cases presented with submucosal, non-ulcerated, endolaryngeal mass with signs and symptoms of airway compromise. In both cases surgical approach was endolaryngeal conservative surgery with CO[2] laser