Dear Editors

We read with interest the well-written recent article by Zelenik et al. reporting on the long-term results of vocal fold augmentation using autologous fat or calcium hydroxylapatite [1].

This is a great effort by experienced laryngologists. Some useful conclusions arise from reading in detail the paper, one major advantage being the authors’ comments on the long-term results, something we agree is not adequately reported in the Vocal Fold Augmentation Literature.

There are some limitations in their study though that dictates a more cautious interpretation of the results. The authors compare two different operative techniques and attempt to withdraw conclusions not taking into consideration possible selection and reporting bias.

One will have trouble comparing—especially in a retrospective way—two entirely different techniques i.e., an office-based (local anesthesia) injection to a direct microlaryngoscopy (under general anesthesia) operation and two different injectables for obvious reasons. The difference in approach, the grade of laryngoscopy, the amount of cooperation (or not) of the patient (in the awake scenario), the fact that the larynx is completely “immobile” when under anesthesia versus a potentially “mobile” target—when in the office scenario—are just few of the factors making comparison of the two techniques difficult if not impossible. Even in the most experienced hands of an expert voice surgeon, the differences between an office based and an under general anesthesia operation are fundamental, and each one has its pros and cons.

It would have been a better idea to compare same technique, i.e., same operation with different injectables, not different technique and different materials in the same study and in a retrospective manner.