Immediate and early injection in unilateral vocal fold paralysis

A paralisia unilateral de prega vocal pode ocorrer, na maioria dos casos, por causas traumáticas, inflamatórias, iatrogênicas, neoplásicas, neurológicas ou idiopáticas. A repercussão na voz, na deglutição e na qualidade de vida, assim como o risco de pneumonia, traz impactos negativos relevantes aos pacientes afetados por essa condição clínica. Os tratamentos disponíveis para essa situação tratam de promover a coaptação glótica. São eles: fonoterapia da voz, medialização da prega vocal seja por injeção ou por tireoplastia (associada ou não a rotação de aritenoide) e reinervação. Esses tratamentos podem ainda ser classificados como temporários e definitivos.1 Considerando-se as causas onde há lesão evidente da inervação motora da laringe, pouca dúvida resta no tratamento que promova a medialização, com ou sem reinervação, de forma definitiva. Entretanto naqueles pacientes em que existe a possibilidade de retorno à função há controvérsia sobre o que fazer e quando fazer. As injeções laríngeas, chamadas também de laringoplastia por injeção, tornaram-se mais populares na última década. Várias razões podem ser atribuídas a esse fenômeno, quais sejam: 1. materiais novos e seguros para injeção, 2. possibilidade de ser feita sob anestesia geral ou local e 3. diversas vias de abordagem -membrana cricotireoidea, incisura tireóidea, transcartilagem tireóidea e transoral. As evidências disponíveis através de uma metanálise não demonstram diferenças entre os resultados de qualidade de voz quando feitas sob anestesia geral ou local.2 Os materiais que podem ser usados, disponíveis em nosso meio, são a gordura autóloga, o ácido hialurônico e a hidroxiapatita. A gordura necessita ser retirada de uma área


Injeção imediata e precoce em paralisia unilateral de prega vocal
In most cases unilateral vocal fold paralysis occurs, secondary to traumatic, inflammatory, iatrogenic, neoplastic, neurological or idiopathic causes. It can result in significant negative effects on voice, swallowing and quality of life, and introduces a risk of aspiration pneumonia to patients affected by it.
The treatments currently available for this situation consist in promoting glottal coaptation. They are: speech therapy, vocal fold medialization, either by injection or thyroplasty (whether or not associated with arytenoid rotation) and reinnervation. These treatments may also be classified as temporary or definitive. 1 When there is obvious injury to the motor innervation of the larynx, the accepted treatment is vocal fold medialization, with or without reinnervation, as a a definitive treatment. However, in patients who have the possibility of functional recovery, there is some controversy about what to do and when to do it.
Laryngeal injections, also called injection laryngoplasty, have become more popular in the last decade. This can be attributed to several factors: 1. new and safe injection materials, 2. the possibility of utilizing general or local anesthesia, and 3. the option of several approaches ---cricothyroid membrane, thyroid notch, trans-thyroid and trans-oral cartilage. The evidence available through a metaanalysis does not show any significant differences between voice quality results when performed under general or local anesthesia. 2 The materials that can be used and are available in Brazil are autologous fat, hyaluronic acid and hydroxyapatite. The fat needs to be removed from a donor area, and requires an incision. Hyaluronic acid is reabsorbed in approximately 60---180 days and hydroxyapatite, if injected into the ଝ Please cite this article as: Sant'Anna GD. Immediate and early injection in unilateral vocal fold paralysis. Braz J Otorhinolaryngol. 2020;86:1---2.
superficial layer of the lamina propria, may impair mucosal vibration.
In recent years, publications have shown promising results with immediate or early injection (up to 6 months) of volatile substances in an attempt to avoid a definitive surgical treatment (thyroplasty). Four retrospective and prospective cohorts were grouped into a meta-analysis, which exhibited significant results. The analysis resulted in 275 grouped patients and the relative risk of not undergoing surgery was 0.25 (0.14-0.45), with a 95 % confidence interval. Therefore, injection laryngoplasty decreases the chance of requiring definitive surgery by up to 75 %. In other words, the chance of a patient undergoing definitive surgical treatment when the injection is not performed is up to 4-fold higher. There are limitations to this meta-analysis. The main one is that there is no randomized clinical trial to study the effect of injection laryngoplasty compared to voice observation and/or speech therapy because the studies are observational. Therefore, there could have been a selection bias favoring the hypothesis being assessed. Similarly, the voice analysis was not an outcome assessed in all studies and it cannot be stated whether or not patients who eventually were not submitted to thyroplasty accepted living with a worse voice. There is also no definition of the optimal timing for the injection ---immediate (up to 3 months) or early (3---6 months). Nevertheless, the analyzed results were classified as degree of evidence C, allowing the recommendation of this treatment modality for paralysis, considering the current stage of scientific knowledge.
There is no explanation about the mechanism by which good vocal and swallowing quality would be maintained, even after resorption of the injected material. My hypothesis is that resorption occurs gradually, day after day, leading to a slow, gradual and consistent adaptation of the entire vocal tract to a new glottic configuration.
In understanding, leads to an unnecessary and difficult wait for a definitive treatment. There is no justification for a 'wait and see' strategy. 2,3 Patients face an increased risk of pulmonary complications, as well as to daily vocal and swallowing consequences caused by glottic insufficiency.

Conflicts of interest
The author declares no conflicts of interest.